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cpython/Lib/test/test_itertools.py
Serhiy Storchaka 46e1ce214b Issue #18783: Removed existing mentions of Python long type in docstrings, 
error messages and comments.
2013-08-27 20:17:03 +03:00

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import unittest
from test import support
from itertools import *
from weakref import proxy
from decimal import Decimal
from fractions import Fraction
import sys
import operator
import random
import copy
import pickle
from functools import reduce
maxsize = support.MAX_Py_ssize_t
minsize = -maxsize-1
def lzip(*args):
return list(zip(*args))
def onearg(x):
'Test function of one argument'
return 2*x
def errfunc(*args):
'Test function that raises an error'
raise ValueError
def gen3():
'Non-restartable source sequence'
for i in (0, 1, 2):
yield i
def isEven(x):
'Test predicate'
return x%2==0
def isOdd(x):
'Test predicate'
return x%2==1
def tupleize(*args):
return args
def irange(n):
for i in range(n):
yield i
class StopNow:
'Class emulating an empty iterable.'
def __iter__(self):
return self
def __next__(self):
raise StopIteration
def take(n, seq):
'Convenience function for partially consuming a long of infinite iterable'
return list(islice(seq, n))
def prod(iterable):
return reduce(operator.mul, iterable, 1)
def fact(n):
'Factorial'
return prod(range(1, n+1))
# root level methods for pickling ability
def testR(r):
return r[0]
def testR2(r):
return r[2]
def underten(x):
return x<10
class TestBasicOps(unittest.TestCase):
def pickletest(self, it, stop=4, take=1, compare=None):
"""Test that an iterator is the same after pickling, also when part-consumed"""
def expand(it, i=0):
# Recursively expand iterables, within sensible bounds
if i > 10:
raise RuntimeError("infinite recursion encountered")
if isinstance(it, str):
return it
try:
l = list(islice(it, stop))
except TypeError:
return it # can't expand it
return [expand(e, i+1) for e in l]
# Test the initial copy against the original
dump = pickle.dumps(it)
i2 = pickle.loads(dump)
self.assertEqual(type(it), type(i2))
a, b = expand(it), expand(i2)
self.assertEqual(a, b)
if compare:
c = expand(compare)
self.assertEqual(a, c)
# Take from the copy, and create another copy and compare them.
i3 = pickle.loads(dump)
took = 0
try:
for i in range(take):
next(i3)
took += 1
except StopIteration:
pass #in case there is less data than 'take'
dump = pickle.dumps(i3)
i4 = pickle.loads(dump)
a, b = expand(i3), expand(i4)
self.assertEqual(a, b)
if compare:
c = expand(compare[took:])
self.assertEqual(a, c);
def test_accumulate(self):
self.assertEqual(list(accumulate(range(10))), # one positional arg
[0, 1, 3, 6, 10, 15, 21, 28, 36, 45])
self.assertEqual(list(accumulate(iterable=range(10))), # kw arg
[0, 1, 3, 6, 10, 15, 21, 28, 36, 45])
for typ in int, complex, Decimal, Fraction: # multiple types
self.assertEqual(
list(accumulate(map(typ, range(10)))),
list(map(typ, [0, 1, 3, 6, 10, 15, 21, 28, 36, 45])))
self.assertEqual(list(accumulate('abc')), ['a', 'ab', 'abc']) # works with non-numeric
self.assertEqual(list(accumulate([])), []) # empty iterable
self.assertEqual(list(accumulate([7])), [7]) # iterable of length one
self.assertRaises(TypeError, accumulate, range(10), 5, 6) # too many args
self.assertRaises(TypeError, accumulate) # too few args
self.assertRaises(TypeError, accumulate, x=range(10)) # unexpected kwd arg
self.assertRaises(TypeError, list, accumulate([1, []])) # args that don't add
s = [2, 8, 9, 5, 7, 0, 3, 4, 1, 6]
self.assertEqual(list(accumulate(s, min)),
[2, 2, 2, 2, 2, 0, 0, 0, 0, 0])
self.assertEqual(list(accumulate(s, max)),
[2, 8, 9, 9, 9, 9, 9, 9, 9, 9])
self.assertEqual(list(accumulate(s, operator.mul)),
[2, 16, 144, 720, 5040, 0, 0, 0, 0, 0])
with self.assertRaises(TypeError):
list(accumulate(s, chr)) # unary-operation
self.pickletest(accumulate(range(10))) # test pickling
def test_chain(self):
def chain2(*iterables):
'Pure python version in the docs'
for it in iterables:
for element in it:
yield element
for c in (chain, chain2):
self.assertEqual(list(c('abc', 'def')), list('abcdef'))
self.assertEqual(list(c('abc')), list('abc'))
self.assertEqual(list(c('')), [])
self.assertEqual(take(4, c('abc', 'def')), list('abcd'))
self.assertRaises(TypeError, list,c(2, 3))
def test_chain_from_iterable(self):
self.assertEqual(list(chain.from_iterable(['abc', 'def'])), list('abcdef'))
self.assertEqual(list(chain.from_iterable(['abc'])), list('abc'))
self.assertEqual(list(chain.from_iterable([''])), [])
self.assertEqual(take(4, chain.from_iterable(['abc', 'def'])), list('abcd'))
self.assertRaises(TypeError, list, chain.from_iterable([2, 3]))
def test_chain_reducible(self):
operators = [copy.deepcopy,
lambda s: pickle.loads(pickle.dumps(s))]
for oper in operators:
it = chain('abc', 'def')
self.assertEqual(list(oper(it)), list('abcdef'))
self.assertEqual(next(it), 'a')
self.assertEqual(list(oper(it)), list('bcdef'))
self.assertEqual(list(oper(chain(''))), [])
self.assertEqual(take(4, oper(chain('abc', 'def'))), list('abcd'))
self.assertRaises(TypeError, list, oper(chain(2, 3)))
self.pickletest(chain('abc', 'def'), compare=list('abcdef'))
def test_combinations(self):
self.assertRaises(TypeError, combinations, 'abc') # missing r argument
self.assertRaises(TypeError, combinations, 'abc', 2, 1) # too many arguments
self.assertRaises(TypeError, combinations, None) # pool is not iterable
self.assertRaises(ValueError, combinations, 'abc', -2) # r is negative
for op in (lambda a:a, lambda a:pickle.loads(pickle.dumps(a))):
self.assertEqual(list(op(combinations('abc', 32))), []) # r > n
self.assertEqual(list(op(combinations('ABCD', 2))),
[('A','B'), ('A','C'), ('A','D'), ('B','C'), ('B','D'), ('C','D')])
testIntermediate = combinations('ABCD', 2)
next(testIntermediate)
self.assertEqual(list(op(testIntermediate)),
[('A','C'), ('A','D'), ('B','C'), ('B','D'), ('C','D')])
self.assertEqual(list(op(combinations(range(4), 3))),
[(0,1,2), (0,1,3), (0,2,3), (1,2,3)])
testIntermediate = combinations(range(4), 3)
next(testIntermediate)
self.assertEqual(list(op(testIntermediate)),
[(0,1,3), (0,2,3), (1,2,3)])
def combinations1(iterable, r):
'Pure python version shown in the docs'
pool = tuple(iterable)
n = len(pool)
if r > n:
return
indices = list(range(r))
yield tuple(pool[i] for i in indices)
while 1:
for i in reversed(range(r)):
if indices[i] != i + n - r:
break
else:
return
indices[i] += 1
for j in range(i+1, r):
indices[j] = indices[j-1] + 1
yield tuple(pool[i] for i in indices)
def combinations2(iterable, r):
'Pure python version shown in the docs'
pool = tuple(iterable)
n = len(pool)
for indices in permutations(range(n), r):
if sorted(indices) == list(indices):
yield tuple(pool[i] for i in indices)
def combinations3(iterable, r):
'Pure python version from cwr()'
pool = tuple(iterable)
n = len(pool)
for indices in combinations_with_replacement(range(n), r):
if len(set(indices)) == r:
yield tuple(pool[i] for i in indices)
for n in range(7):
values = [5*x-12 for x in range(n)]
for r in range(n+2):
result = list(combinations(values, r))
self.assertEqual(len(result), 0 if r>n else fact(n) / fact(r) / fact(n-r)) # right number of combs
self.assertEqual(len(result), len(set(result))) # no repeats
self.assertEqual(result, sorted(result)) # lexicographic order
for c in result:
self.assertEqual(len(c), r) # r-length combinations
self.assertEqual(len(set(c)), r) # no duplicate elements
self.assertEqual(list(c), sorted(c)) # keep original ordering
self.assertTrue(all(e in values for e in c)) # elements taken from input iterable
self.assertEqual(list(c),
[e for e in values if e in c]) # comb is a subsequence of the input iterable
self.assertEqual(result, list(combinations1(values, r))) # matches first pure python version
self.assertEqual(result, list(combinations2(values, r))) # matches second pure python version
self.assertEqual(result, list(combinations3(values, r))) # matches second pure python version
self.pickletest(combinations(values, r)) # test pickling
# Test implementation detail: tuple re-use
@support.impl_detail("tuple reuse is specific to CPython")
def test_combinations_tuple_reuse(self):
self.assertEqual(len(set(map(id, combinations('abcde', 3)))), 1)
self.assertNotEqual(len(set(map(id, list(combinations('abcde', 3))))), 1)
def test_combinations_with_replacement(self):
cwr = combinations_with_replacement
self.assertRaises(TypeError, cwr, 'abc') # missing r argument
self.assertRaises(TypeError, cwr, 'abc', 2, 1) # too many arguments
self.assertRaises(TypeError, cwr, None) # pool is not iterable
self.assertRaises(ValueError, cwr, 'abc', -2) # r is negative
for op in (lambda a:a, lambda a:pickle.loads(pickle.dumps(a))):
self.assertEqual(list(op(cwr('ABC', 2))),
[('A','A'), ('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
testIntermediate = cwr('ABC', 2)
next(testIntermediate)
self.assertEqual(list(op(testIntermediate)),
[('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
def cwr1(iterable, r):
'Pure python version shown in the docs'
# number items returned: (n+r-1)! / r! / (n-1)! when n>0
pool = tuple(iterable)
n = len(pool)
if not n and r:
return
indices = [0] * r
yield tuple(pool[i] for i in indices)
while 1:
for i in reversed(range(r)):
if indices[i] != n - 1:
break
else:
return
indices[i:] = [indices[i] + 1] * (r - i)
yield tuple(pool[i] for i in indices)
def cwr2(iterable, r):
'Pure python version shown in the docs'
pool = tuple(iterable)
n = len(pool)
for indices in product(range(n), repeat=r):
if sorted(indices) == list(indices):
yield tuple(pool[i] for i in indices)
def numcombs(n, r):
if not n:
return 0 if r else 1
return fact(n+r-1) / fact(r)/ fact(n-1)
for n in range(7):
values = [5*x-12 for x in range(n)]
for r in range(n+2):
result = list(cwr(values, r))
self.assertEqual(len(result), numcombs(n, r)) # right number of combs
self.assertEqual(len(result), len(set(result))) # no repeats
self.assertEqual(result, sorted(result)) # lexicographic order
regular_combs = list(combinations(values, r)) # compare to combs without replacement
if n == 0 or r <= 1:
self.assertEqual(result, regular_combs) # cases that should be identical
else:
self.assertTrue(set(result) >= set(regular_combs)) # rest should be supersets of regular combs
for c in result:
self.assertEqual(len(c), r) # r-length combinations
noruns = [k for k,v in groupby(c)] # combo without consecutive repeats
self.assertEqual(len(noruns), len(set(noruns))) # no repeats other than consecutive
self.assertEqual(list(c), sorted(c)) # keep original ordering
self.assertTrue(all(e in values for e in c)) # elements taken from input iterable
self.assertEqual(noruns,
[e for e in values if e in c]) # comb is a subsequence of the input iterable
self.assertEqual(result, list(cwr1(values, r))) # matches first pure python version
self.assertEqual(result, list(cwr2(values, r))) # matches second pure python version
self.pickletest(cwr(values,r)) # test pickling
# Test implementation detail: tuple re-use
@support.impl_detail("tuple reuse is specific to CPython")
def test_combinations_with_replacement_tuple_reuse(self):
cwr = combinations_with_replacement
self.assertEqual(len(set(map(id, cwr('abcde', 3)))), 1)
self.assertNotEqual(len(set(map(id, list(cwr('abcde', 3))))), 1)
def test_permutations(self):
self.assertRaises(TypeError, permutations) # too few arguments
self.assertRaises(TypeError, permutations, 'abc', 2, 1) # too many arguments
self.assertRaises(TypeError, permutations, None) # pool is not iterable
self.assertRaises(ValueError, permutations, 'abc', -2) # r is negative
self.assertEqual(list(permutations('abc', 32)), []) # r > n
self.assertRaises(TypeError, permutations, 'abc', 's') # r is not an int or None
self.assertEqual(list(permutations(range(3), 2)),
[(0,1), (0,2), (1,0), (1,2), (2,0), (2,1)])
def permutations1(iterable, r=None):
'Pure python version shown in the docs'
pool = tuple(iterable)
n = len(pool)
r = n if r is None else r
if r > n:
return
indices = list(range(n))
cycles = list(range(n-r+1, n+1))[::-1]
yield tuple(pool[i] for i in indices[:r])
while n:
for i in reversed(range(r)):
cycles[i] -= 1
if cycles[i] == 0:
indices[i:] = indices[i+1:] + indices[i:i+1]
cycles[i] = n - i
else:
j = cycles[i]
indices[i], indices[-j] = indices[-j], indices[i]
yield tuple(pool[i] for i in indices[:r])
break
else:
return
def permutations2(iterable, r=None):
'Pure python version shown in the docs'
pool = tuple(iterable)
n = len(pool)
r = n if r is None else r
for indices in product(range(n), repeat=r):
if len(set(indices)) == r:
yield tuple(pool[i] for i in indices)
for n in range(7):
values = [5*x-12 for x in range(n)]
for r in range(n+2):
result = list(permutations(values, r))
self.assertEqual(len(result), 0 if r>n else fact(n) / fact(n-r)) # right number of perms
self.assertEqual(len(result), len(set(result))) # no repeats
self.assertEqual(result, sorted(result)) # lexicographic order
for p in result:
self.assertEqual(len(p), r) # r-length permutations
self.assertEqual(len(set(p)), r) # no duplicate elements
self.assertTrue(all(e in values for e in p)) # elements taken from input iterable
self.assertEqual(result, list(permutations1(values, r))) # matches first pure python version
self.assertEqual(result, list(permutations2(values, r))) # matches second pure python version
if r == n:
self.assertEqual(result, list(permutations(values, None))) # test r as None
self.assertEqual(result, list(permutations(values))) # test default r
self.pickletest(permutations(values, r)) # test pickling
@support.impl_detail("tuple resuse is CPython specific")
def test_permutations_tuple_reuse(self):
self.assertEqual(len(set(map(id, permutations('abcde', 3)))), 1)
self.assertNotEqual(len(set(map(id, list(permutations('abcde', 3))))), 1)
def test_combinatorics(self):
# Test relationships between product(), permutations(),
# combinations() and combinations_with_replacement().
for n in range(6):
s = 'ABCDEFG'[:n]
for r in range(8):
prod = list(product(s, repeat=r))
cwr = list(combinations_with_replacement(s, r))
perm = list(permutations(s, r))
comb = list(combinations(s, r))
# Check size
self.assertEqual(len(prod), n**r)
self.assertEqual(len(cwr), (fact(n+r-1) / fact(r)/ fact(n-1)) if n else (not r))
self.assertEqual(len(perm), 0 if r>n else fact(n) / fact(n-r))
self.assertEqual(len(comb), 0 if r>n else fact(n) / fact(r) / fact(n-r))
# Check lexicographic order without repeated tuples
self.assertEqual(prod, sorted(set(prod)))
self.assertEqual(cwr, sorted(set(cwr)))
self.assertEqual(perm, sorted(set(perm)))
self.assertEqual(comb, sorted(set(comb)))
# Check interrelationships
self.assertEqual(cwr, [t for t in prod if sorted(t)==list(t)]) # cwr: prods which are sorted
self.assertEqual(perm, [t for t in prod if len(set(t))==r]) # perm: prods with no dups
self.assertEqual(comb, [t for t in perm if sorted(t)==list(t)]) # comb: perms that are sorted
self.assertEqual(comb, [t for t in cwr if len(set(t))==r]) # comb: cwrs without dups
self.assertEqual(comb, list(filter(set(cwr).__contains__, perm))) # comb: perm that is a cwr
self.assertEqual(comb, list(filter(set(perm).__contains__, cwr))) # comb: cwr that is a perm
self.assertEqual(comb, sorted(set(cwr) & set(perm))) # comb: both a cwr and a perm
def test_compress(self):
self.assertEqual(list(compress(data='ABCDEF', selectors=[1,0,1,0,1,1])), list('ACEF'))
self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
self.assertEqual(list(compress('ABCDEF', [0,0,0,0,0,0])), list(''))
self.assertEqual(list(compress('ABCDEF', [1,1,1,1,1,1])), list('ABCDEF'))
self.assertEqual(list(compress('ABCDEF', [1,0,1])), list('AC'))
self.assertEqual(list(compress('ABC', [0,1,1,1,1,1])), list('BC'))
n = 10000
data = chain.from_iterable(repeat(range(6), n))
selectors = chain.from_iterable(repeat((0, 1)))
self.assertEqual(list(compress(data, selectors)), [1,3,5] * n)
self.assertRaises(TypeError, compress, None, range(6)) # 1st arg not iterable
self.assertRaises(TypeError, compress, range(6), None) # 2nd arg not iterable
self.assertRaises(TypeError, compress, range(6)) # too few args
self.assertRaises(TypeError, compress, range(6), None) # too many args
# check copy, deepcopy, pickle
for op in (lambda a:copy.copy(a), lambda a:copy.deepcopy(a), lambda a:pickle.loads(pickle.dumps(a))):
for data, selectors, result1, result2 in [
('ABCDEF', [1,0,1,0,1,1], 'ACEF', 'CEF'),
('ABCDEF', [0,0,0,0,0,0], '', ''),
('ABCDEF', [1,1,1,1,1,1], 'ABCDEF', 'BCDEF'),
('ABCDEF', [1,0,1], 'AC', 'C'),
('ABC', [0,1,1,1,1,1], 'BC', 'C'),
]:
self.assertEqual(list(op(compress(data=data, selectors=selectors))), list(result1))
self.assertEqual(list(op(compress(data, selectors))), list(result1))
testIntermediate = compress(data, selectors)
if result1:
next(testIntermediate)
self.assertEqual(list(op(testIntermediate)), list(result2))
def test_count(self):
self.assertEqual(lzip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
self.assertEqual(lzip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
self.assertEqual(take(2, lzip('abc',count(3))), [('a', 3), ('b', 4)])
self.assertEqual(take(2, zip('abc',count(-1))), [('a', -1), ('b', 0)])
self.assertEqual(take(2, zip('abc',count(-3))), [('a', -3), ('b', -2)])
self.assertRaises(TypeError, count, 2, 3, 4)
self.assertRaises(TypeError, count, 'a')
self.assertEqual(list(islice(count(maxsize-5), 10)),
list(range(maxsize-5, maxsize+5)))
self.assertEqual(list(islice(count(-maxsize-5), 10)),
list(range(-maxsize-5, -maxsize+5)))
self.assertEqual(list(islice(count(10, maxsize+5), 3)),
list(range(10, 10+3*(maxsize+5), maxsize+5)))
c = count(3)
self.assertEqual(repr(c), 'count(3)')
next(c)
self.assertEqual(repr(c), 'count(4)')
c = count(-9)
self.assertEqual(repr(c), 'count(-9)')
next(c)
self.assertEqual(repr(count(10.25)), 'count(10.25)')
self.assertEqual(next(c), -8)
for i in (-sys.maxsize-5, -sys.maxsize+5 ,-10, -1, 0, 10, sys.maxsize-5, sys.maxsize+5):
# Test repr
r1 = repr(count(i))
r2 = 'count(%r)'.__mod__(i)
self.assertEqual(r1, r2)
# check copy, deepcopy, pickle
for value in -3, 3, maxsize-5, maxsize+5:
c = count(value)
self.assertEqual(next(copy.copy(c)), value)
self.assertEqual(next(copy.deepcopy(c)), value)
self.pickletest(count(value))
#check proper internal error handling for large "step' sizes
count(1, maxsize+5); sys.exc_info()
def test_count_with_stride(self):
self.assertEqual(lzip('abc',count(2,3)), [('a', 2), ('b', 5), ('c', 8)])
self.assertEqual(lzip('abc',count(start=2,step=3)),
[('a', 2), ('b', 5), ('c', 8)])
self.assertEqual(lzip('abc',count(step=-1)),
[('a', 0), ('b', -1), ('c', -2)])
self.assertEqual(lzip('abc',count(2,0)), [('a', 2), ('b', 2), ('c', 2)])
self.assertEqual(lzip('abc',count(2,1)), [('a', 2), ('b', 3), ('c', 4)])
self.assertEqual(lzip('abc',count(2,3)), [('a', 2), ('b', 5), ('c', 8)])
self.assertEqual(take(20, count(maxsize-15, 3)), take(20, range(maxsize-15, maxsize+100, 3)))
self.assertEqual(take(20, count(-maxsize-15, 3)), take(20, range(-maxsize-15,-maxsize+100, 3)))
self.assertEqual(take(3, count(2, 3.25-4j)), [2, 5.25-4j, 8.5-8j])
self.assertEqual(take(3, count(Decimal('1.1'), Decimal('.1'))),
[Decimal('1.1'), Decimal('1.2'), Decimal('1.3')])
self.assertEqual(take(3, count(Fraction(2,3), Fraction(1,7))),
[Fraction(2,3), Fraction(17,21), Fraction(20,21)])
self.assertEqual(repr(take(3, count(10, 2.5))), repr([10, 12.5, 15.0]))
c = count(3, 5)
self.assertEqual(repr(c), 'count(3, 5)')
next(c)
self.assertEqual(repr(c), 'count(8, 5)')
c = count(-9, 0)
self.assertEqual(repr(c), 'count(-9, 0)')
next(c)
self.assertEqual(repr(c), 'count(-9, 0)')
c = count(-9, -3)
self.assertEqual(repr(c), 'count(-9, -3)')
next(c)
self.assertEqual(repr(c), 'count(-12, -3)')
self.assertEqual(repr(c), 'count(-12, -3)')
self.assertEqual(repr(count(10.5, 1.25)), 'count(10.5, 1.25)')
self.assertEqual(repr(count(10.5, 1)), 'count(10.5)') # suppress step=1 when it's an int
self.assertEqual(repr(count(10.5, 1.00)), 'count(10.5, 1.0)') # do show float values lilke 1.0
for i in (-sys.maxsize-5, -sys.maxsize+5 ,-10, -1, 0, 10, sys.maxsize-5, sys.maxsize+5):
for j in (-sys.maxsize-5, -sys.maxsize+5 ,-10, -1, 0, 1, 10, sys.maxsize-5, sys.maxsize+5):
# Test repr
r1 = repr(count(i, j))
if j == 1:
r2 = ('count(%r)' % i)
else:
r2 = ('count(%r, %r)' % (i, j))
self.assertEqual(r1, r2)
self.pickletest(count(i, j))
def test_cycle(self):
self.assertEqual(take(10, cycle('abc')), list('abcabcabca'))
self.assertEqual(list(cycle('')), [])
self.assertRaises(TypeError, cycle)
self.assertRaises(TypeError, cycle, 5)
self.assertEqual(list(islice(cycle(gen3()),10)), [0,1,2,0,1,2,0,1,2,0])
# check copy, deepcopy, pickle
c = cycle('abc')
self.assertEqual(next(c), 'a')
#simple copy currently not supported, because __reduce__ returns
#an internal iterator
#self.assertEqual(take(10, copy.copy(c)), list('bcabcabcab'))
self.assertEqual(take(10, copy.deepcopy(c)), list('bcabcabcab'))
self.assertEqual(take(10, pickle.loads(pickle.dumps(c))), list('bcabcabcab'))
next(c)
self.assertEqual(take(10, pickle.loads(pickle.dumps(c))), list('cabcabcabc'))
self.pickletest(cycle('abc'))
def test_groupby(self):
# Check whether it accepts arguments correctly
self.assertEqual([], list(groupby([])))
self.assertEqual([], list(groupby([], key=id)))
self.assertRaises(TypeError, list, groupby('abc', []))
self.assertRaises(TypeError, groupby, None)
self.assertRaises(TypeError, groupby, 'abc', lambda x:x, 10)
# Check normal input
s = [(0, 10, 20), (0, 11,21), (0,12,21), (1,13,21), (1,14,22),
(2,15,22), (3,16,23), (3,17,23)]
dup = []
for k, g in groupby(s, lambda r:r[0]):
for elem in g:
self.assertEqual(k, elem[0])
dup.append(elem)
self.assertEqual(s, dup)
# Check normal pickled
dup = []
for k, g in pickle.loads(pickle.dumps(groupby(s, testR))):
for elem in g:
self.assertEqual(k, elem[0])
dup.append(elem)
self.assertEqual(s, dup)
# Check nested case
dup = []
for k, g in groupby(s, testR):
for ik, ig in groupby(g, testR2):
for elem in ig:
self.assertEqual(k, elem[0])
self.assertEqual(ik, elem[2])
dup.append(elem)
self.assertEqual(s, dup)
# Check nested and pickled
dup = []
for k, g in pickle.loads(pickle.dumps(groupby(s, testR))):
for ik, ig in pickle.loads(pickle.dumps(groupby(g, testR2))):
for elem in ig:
self.assertEqual(k, elem[0])
self.assertEqual(ik, elem[2])
dup.append(elem)
self.assertEqual(s, dup)
# Check case where inner iterator is not used
keys = [k for k, g in groupby(s, testR)]
expectedkeys = set([r[0] for r in s])
self.assertEqual(set(keys), expectedkeys)
self.assertEqual(len(keys), len(expectedkeys))
# Exercise pipes and filters style
s = 'abracadabra'
# sort s | uniq
r = [k for k, g in groupby(sorted(s))]
self.assertEqual(r, ['a', 'b', 'c', 'd', 'r'])
# sort s | uniq -d
r = [k for k, g in groupby(sorted(s)) if list(islice(g,1,2))]
self.assertEqual(r, ['a', 'b', 'r'])
# sort s | uniq -c
r = [(len(list(g)), k) for k, g in groupby(sorted(s))]
self.assertEqual(r, [(5, 'a'), (2, 'b'), (1, 'c'), (1, 'd'), (2, 'r')])
# sort s | uniq -c | sort -rn | head -3
r = sorted([(len(list(g)) , k) for k, g in groupby(sorted(s))], reverse=True)[:3]
self.assertEqual(r, [(5, 'a'), (2, 'r'), (2, 'b')])
# iter.__next__ failure
class ExpectedError(Exception):
pass
def delayed_raise(n=0):
for i in range(n):
yield 'yo'
raise ExpectedError
def gulp(iterable, keyp=None, func=list):
return [func(g) for k, g in groupby(iterable, keyp)]
# iter.__next__ failure on outer object
self.assertRaises(ExpectedError, gulp, delayed_raise(0))
# iter.__next__ failure on inner object
self.assertRaises(ExpectedError, gulp, delayed_raise(1))
# __cmp__ failure
class DummyCmp:
def __eq__(self, dst):
raise ExpectedError
s = [DummyCmp(), DummyCmp(), None]
# __eq__ failure on outer object
self.assertRaises(ExpectedError, gulp, s, func=id)
# __eq__ failure on inner object
self.assertRaises(ExpectedError, gulp, s)
# keyfunc failure
def keyfunc(obj):
if keyfunc.skip > 0:
keyfunc.skip -= 1
return obj
else:
raise ExpectedError
# keyfunc failure on outer object
keyfunc.skip = 0
self.assertRaises(ExpectedError, gulp, [None], keyfunc)
keyfunc.skip = 1
self.assertRaises(ExpectedError, gulp, [None, None], keyfunc)
def test_filter(self):
self.assertEqual(list(filter(isEven, range(6))), [0,2,4])
self.assertEqual(list(filter(None, [0,1,0,2,0])), [1,2])
self.assertEqual(list(filter(bool, [0,1,0,2,0])), [1,2])
self.assertEqual(take(4, filter(isEven, count())), [0,2,4,6])
self.assertRaises(TypeError, filter)
self.assertRaises(TypeError, filter, lambda x:x)
self.assertRaises(TypeError, filter, lambda x:x, range(6), 7)
self.assertRaises(TypeError, filter, isEven, 3)
self.assertRaises(TypeError, next, filter(range(6), range(6)))
# check copy, deepcopy, pickle
ans = [0,2,4]
c = filter(isEven, range(6))
self.assertEqual(list(copy.copy(c)), ans)
c = filter(isEven, range(6))
self.assertEqual(list(copy.deepcopy(c)), ans)
c = filter(isEven, range(6))
self.assertEqual(list(pickle.loads(pickle.dumps(c))), ans)
next(c)
self.assertEqual(list(pickle.loads(pickle.dumps(c))), ans[1:])
c = filter(isEven, range(6))
self.pickletest(c)
def test_filterfalse(self):
self.assertEqual(list(filterfalse(isEven, range(6))), [1,3,5])
self.assertEqual(list(filterfalse(None, [0,1,0,2,0])), [0,0,0])
self.assertEqual(list(filterfalse(bool, [0,1,0,2,0])), [0,0,0])
self.assertEqual(take(4, filterfalse(isEven, count())), [1,3,5,7])
self.assertRaises(TypeError, filterfalse)
self.assertRaises(TypeError, filterfalse, lambda x:x)
self.assertRaises(TypeError, filterfalse, lambda x:x, range(6), 7)
self.assertRaises(TypeError, filterfalse, isEven, 3)
self.assertRaises(TypeError, next, filterfalse(range(6), range(6)))
self.pickletest(filterfalse(isEven, range(6)))
def test_zip(self):
# XXX This is rather silly now that builtin zip() calls zip()...
ans = [(x,y) for x, y in zip('abc',count())]
self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
self.assertEqual(list(zip('abc', range(6))), lzip('abc', range(6)))
self.assertEqual(list(zip('abcdef', range(3))), lzip('abcdef', range(3)))
self.assertEqual(take(3,zip('abcdef', count())), lzip('abcdef', range(3)))
self.assertEqual(list(zip('abcdef')), lzip('abcdef'))
self.assertEqual(list(zip()), lzip())
self.assertRaises(TypeError, zip, 3)
self.assertRaises(TypeError, zip, range(3), 3)
self.assertEqual([tuple(list(pair)) for pair in zip('abc', 'def')],
lzip('abc', 'def'))
self.assertEqual([pair for pair in zip('abc', 'def')],
lzip('abc', 'def'))
@support.impl_detail("tuple reuse is specific to CPython")
def test_zip_tuple_reuse(self):
ids = list(map(id, zip('abc', 'def')))
self.assertEqual(min(ids), max(ids))
ids = list(map(id, list(zip('abc', 'def'))))
self.assertEqual(len(dict.fromkeys(ids)), len(ids))
# check copy, deepcopy, pickle
ans = [(x,y) for x, y in copy.copy(zip('abc',count()))]
self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
ans = [(x,y) for x, y in copy.deepcopy(zip('abc',count()))]
self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
ans = [(x,y) for x, y in pickle.loads(pickle.dumps(zip('abc',count())))]
self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
testIntermediate = zip('abc',count())
next(testIntermediate)
ans = [(x,y) for x, y in pickle.loads(pickle.dumps(testIntermediate))]
self.assertEqual(ans, [('b', 1), ('c', 2)])
self.pickletest(zip('abc', count()))
def test_ziplongest(self):
for args in [
['abc', range(6)],
[range(6), 'abc'],
[range(1000), range(2000,2100), range(3000,3050)],
[range(1000), range(0), range(3000,3050), range(1200), range(1500)],
[range(1000), range(0), range(3000,3050), range(1200), range(1500), range(0)],
]:
target = [tuple([arg[i] if i < len(arg) else None for arg in args])
for i in range(max(map(len, args)))]
self.assertEqual(list(zip_longest(*args)), target)
self.assertEqual(list(zip_longest(*args, **{})), target)
target = [tuple((e is None and 'X' or e) for e in t) for t in target] # Replace None fills with 'X'
self.assertEqual(list(zip_longest(*args, **dict(fillvalue='X'))), target)
self.assertEqual(take(3,zip_longest('abcdef', count())), list(zip('abcdef', range(3)))) # take 3 from infinite input
self.assertEqual(list(zip_longest()), list(zip()))
self.assertEqual(list(zip_longest([])), list(zip([])))
self.assertEqual(list(zip_longest('abcdef')), list(zip('abcdef')))
self.assertEqual(list(zip_longest('abc', 'defg', **{})),
list(zip(list('abc')+[None], 'defg'))) # empty keyword dict
self.assertRaises(TypeError, zip_longest, 3)
self.assertRaises(TypeError, zip_longest, range(3), 3)
for stmt in [
"zip_longest('abc', fv=1)",
"zip_longest('abc', fillvalue=1, bogus_keyword=None)",
]:
try:
eval(stmt, globals(), locals())
except TypeError:
pass
else:
self.fail('Did not raise Type in: ' + stmt)
self.assertEqual([tuple(list(pair)) for pair in zip_longest('abc', 'def')],
list(zip('abc', 'def')))
self.assertEqual([pair for pair in zip_longest('abc', 'def')],
list(zip('abc', 'def')))
@support.impl_detail("tuple reuse is specific to CPython")
def test_zip_longest_tuple_reuse(self):
ids = list(map(id, zip_longest('abc', 'def')))
self.assertEqual(min(ids), max(ids))
ids = list(map(id, list(zip_longest('abc', 'def'))))
self.assertEqual(len(dict.fromkeys(ids)), len(ids))
def test_zip_longest_pickling(self):
self.pickletest(zip_longest("abc", "def"))
self.pickletest(zip_longest("abc", "defgh"))
self.pickletest(zip_longest("abc", "defgh", fillvalue=1))
self.pickletest(zip_longest("", "defgh"))
def test_bug_7244(self):
class Repeater:
# this class is similar to itertools.repeat
def __init__(self, o, t, e):
self.o = o
self.t = int(t)
self.e = e
def __iter__(self): # its iterator is itself
return self
def __next__(self):
if self.t > 0:
self.t -= 1
return self.o
else:
raise self.e
# Formerly this code in would fail in debug mode
# with Undetected Error and Stop Iteration
r1 = Repeater(1, 3, StopIteration)
r2 = Repeater(2, 4, StopIteration)
def run(r1, r2):
result = []
for i, j in zip_longest(r1, r2, fillvalue=0):
with support.captured_output('stdout'):
print((i, j))
result.append((i, j))
return result
self.assertEqual(run(r1, r2), [(1,2), (1,2), (1,2), (0,2)])
# Formerly, the RuntimeError would be lost
# and StopIteration would stop as expected
r1 = Repeater(1, 3, RuntimeError)
r2 = Repeater(2, 4, StopIteration)
it = zip_longest(r1, r2, fillvalue=0)
self.assertEqual(next(it), (1, 2))
self.assertEqual(next(it), (1, 2))
self.assertEqual(next(it), (1, 2))
self.assertRaises(RuntimeError, next, it)
def test_product(self):
for args, result in [
([], [()]), # zero iterables
(['ab'], [('a',), ('b',)]), # one iterable
([range(2), range(3)], [(0,0), (0,1), (0,2), (1,0), (1,1), (1,2)]), # two iterables
([range(0), range(2), range(3)], []), # first iterable with zero length
([range(2), range(0), range(3)], []), # middle iterable with zero length
([range(2), range(3), range(0)], []), # last iterable with zero length
]:
self.assertEqual(list(product(*args)), result)
for r in range(4):
self.assertEqual(list(product(*(args*r))),
list(product(*args, **dict(repeat=r))))
self.assertEqual(len(list(product(*[range(7)]*6))), 7**6)
self.assertRaises(TypeError, product, range(6), None)
def product1(*args, **kwds):
pools = list(map(tuple, args)) * kwds.get('repeat', 1)
n = len(pools)
if n == 0:
yield ()
return
if any(len(pool) == 0 for pool in pools):
return
indices = [0] * n
yield tuple(pool[i] for pool, i in zip(pools, indices))
while 1:
for i in reversed(range(n)): # right to left
if indices[i] == len(pools[i]) - 1:
continue
indices[i] += 1
for j in range(i+1, n):
indices[j] = 0
yield tuple(pool[i] for pool, i in zip(pools, indices))
break
else:
return
def product2(*args, **kwds):
'Pure python version used in docs'
pools = list(map(tuple, args)) * kwds.get('repeat', 1)
result = [[]]
for pool in pools:
result = [x+[y] for x in result for y in pool]
for prod in result:
yield tuple(prod)
argtypes = ['', 'abc', '', range(0), range(4), dict(a=1, b=2, c=3),
set('abcdefg'), range(11), tuple(range(13))]
for i in range(100):
args = [random.choice(argtypes) for j in range(random.randrange(5))]
expected_len = prod(map(len, args))
self.assertEqual(len(list(product(*args))), expected_len)
self.assertEqual(list(product(*args)), list(product1(*args)))
self.assertEqual(list(product(*args)), list(product2(*args)))
args = map(iter, args)
self.assertEqual(len(list(product(*args))), expected_len)
@support.impl_detail("tuple reuse is specific to CPython")
def test_product_tuple_reuse(self):
self.assertEqual(len(set(map(id, product('abc', 'def')))), 1)
self.assertNotEqual(len(set(map(id, list(product('abc', 'def'))))), 1)
def test_product_pickling(self):
# check copy, deepcopy, pickle
for args, result in [
([], [()]), # zero iterables
(['ab'], [('a',), ('b',)]), # one iterable
([range(2), range(3)], [(0,0), (0,1), (0,2), (1,0), (1,1), (1,2)]), # two iterables
([range(0), range(2), range(3)], []), # first iterable with zero length
([range(2), range(0), range(3)], []), # middle iterable with zero length
([range(2), range(3), range(0)], []), # last iterable with zero length
]:
self.assertEqual(list(copy.copy(product(*args))), result)
self.assertEqual(list(copy.deepcopy(product(*args))), result)
self.pickletest(product(*args))
def test_repeat(self):
self.assertEqual(list(repeat(object='a', times=3)), ['a', 'a', 'a'])
self.assertEqual(lzip(range(3),repeat('a')),
[(0, 'a'), (1, 'a'), (2, 'a')])
self.assertEqual(list(repeat('a', 3)), ['a', 'a', 'a'])
self.assertEqual(take(3, repeat('a')), ['a', 'a', 'a'])
self.assertEqual(list(repeat('a', 0)), [])
self.assertEqual(list(repeat('a', -3)), [])
self.assertRaises(TypeError, repeat)
self.assertRaises(TypeError, repeat, None, 3, 4)
self.assertRaises(TypeError, repeat, None, 'a')
r = repeat(1+0j)
self.assertEqual(repr(r), 'repeat((1+0j))')
r = repeat(1+0j, 5)
self.assertEqual(repr(r), 'repeat((1+0j), 5)')
list(r)
self.assertEqual(repr(r), 'repeat((1+0j), 0)')
# check copy, deepcopy, pickle
c = repeat(object='a', times=10)
self.assertEqual(next(c), 'a')
self.assertEqual(take(2, copy.copy(c)), list('a' * 2))
self.assertEqual(take(2, copy.deepcopy(c)), list('a' * 2))
self.pickletest(repeat(object='a', times=10))
def test_map(self):
self.assertEqual(list(map(operator.pow, range(3), range(1,7))),
[0**1, 1**2, 2**3])
self.assertEqual(list(map(tupleize, 'abc', range(5))),
[('a',0),('b',1),('c',2)])
self.assertEqual(list(map(tupleize, 'abc', count())),
[('a',0),('b',1),('c',2)])
self.assertEqual(take(2,map(tupleize, 'abc', count())),
[('a',0),('b',1)])
self.assertEqual(list(map(operator.pow, [])), [])
self.assertRaises(TypeError, map)
self.assertRaises(TypeError, list, map(None, range(3), range(3)))
self.assertRaises(TypeError, map, operator.neg)
self.assertRaises(TypeError, next, map(10, range(5)))
self.assertRaises(ValueError, next, map(errfunc, [4], [5]))
self.assertRaises(TypeError, next, map(onearg, [4], [5]))
# check copy, deepcopy, pickle
ans = [('a',0),('b',1),('c',2)]
c = map(tupleize, 'abc', count())
self.assertEqual(list(copy.copy(c)), ans)
c = map(tupleize, 'abc', count())
self.assertEqual(list(copy.deepcopy(c)), ans)
c = map(tupleize, 'abc', count())
self.pickletest(c)
def test_starmap(self):
self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
[0**1, 1**2, 2**3])
self.assertEqual(take(3, starmap(operator.pow, zip(count(), count(1)))),
[0**1, 1**2, 2**3])
self.assertEqual(list(starmap(operator.pow, [])), [])
self.assertEqual(list(starmap(operator.pow, [iter([4,5])])), [4**5])
self.assertRaises(TypeError, list, starmap(operator.pow, [None]))
self.assertRaises(TypeError, starmap)
self.assertRaises(TypeError, starmap, operator.pow, [(4,5)], 'extra')
self.assertRaises(TypeError, next, starmap(10, [(4,5)]))
self.assertRaises(ValueError, next, starmap(errfunc, [(4,5)]))
self.assertRaises(TypeError, next, starmap(onearg, [(4,5)]))
# check copy, deepcopy, pickle
ans = [0**1, 1**2, 2**3]
c = starmap(operator.pow, zip(range(3), range(1,7)))
self.assertEqual(list(copy.copy(c)), ans)
c = starmap(operator.pow, zip(range(3), range(1,7)))
self.assertEqual(list(copy.deepcopy(c)), ans)
c = starmap(operator.pow, zip(range(3), range(1,7)))
self.pickletest(c)
def test_islice(self):
for args in [ # islice(args) should agree with range(args)
(10, 20, 3),
(10, 3, 20),
(10, 20),
(10, 3),
(20,)
]:
self.assertEqual(list(islice(range(100), *args)),
list(range(*args)))
for args, tgtargs in [ # Stop when seqn is exhausted
((10, 110, 3), ((10, 100, 3))),
((10, 110), ((10, 100))),
((110,), (100,))
]:
self.assertEqual(list(islice(range(100), *args)),
list(range(*tgtargs)))
# Test stop=None
self.assertEqual(list(islice(range(10), None)), list(range(10)))
self.assertEqual(list(islice(range(10), None, None)), list(range(10)))
self.assertEqual(list(islice(range(10), None, None, None)), list(range(10)))
self.assertEqual(list(islice(range(10), 2, None)), list(range(2, 10)))
self.assertEqual(list(islice(range(10), 1, None, 2)), list(range(1, 10, 2)))
# Test number of items consumed SF #1171417
it = iter(range(10))
self.assertEqual(list(islice(it, 3)), list(range(3)))
self.assertEqual(list(it), list(range(3, 10)))
# Test invalid arguments
ra = range(10)
self.assertRaises(TypeError, islice, ra)
self.assertRaises(TypeError, islice, ra, 1, 2, 3, 4)
self.assertRaises(ValueError, islice, ra, -5, 10, 1)
self.assertRaises(ValueError, islice, ra, 1, -5, -1)
self.assertRaises(ValueError, islice, ra, 1, 10, -1)
self.assertRaises(ValueError, islice, ra, 1, 10, 0)
self.assertRaises(ValueError, islice, ra, 'a')
self.assertRaises(ValueError, islice, ra, 'a', 1)
self.assertRaises(ValueError, islice, ra, 1, 'a')
self.assertRaises(ValueError, islice, ra, 'a', 1, 1)
self.assertRaises(ValueError, islice, ra, 1, 'a', 1)
self.assertEqual(len(list(islice(count(), 1, 10, maxsize))), 1)
# Issue #10323: Less islice in a predictable state
c = count()
self.assertEqual(list(islice(c, 1, 3, 50)), [1])
self.assertEqual(next(c), 3)
# check copy, deepcopy, pickle
for args in [ # islice(args) should agree with range(args)
(10, 20, 3),
(10, 3, 20),
(10, 20),
(10, 3),
(20,)
]:
self.assertEqual(list(copy.copy(islice(range(100), *args))),
list(range(*args)))
self.assertEqual(list(copy.deepcopy(islice(range(100), *args))),
list(range(*args)))
self.pickletest(islice(range(100), *args))
def test_takewhile(self):
data = [1, 3, 5, 20, 2, 4, 6, 8]
self.assertEqual(list(takewhile(underten, data)), [1, 3, 5])
self.assertEqual(list(takewhile(underten, [])), [])
self.assertRaises(TypeError, takewhile)
self.assertRaises(TypeError, takewhile, operator.pow)
self.assertRaises(TypeError, takewhile, operator.pow, [(4,5)], 'extra')
self.assertRaises(TypeError, next, takewhile(10, [(4,5)]))
self.assertRaises(ValueError, next, takewhile(errfunc, [(4,5)]))
t = takewhile(bool, [1, 1, 1, 0, 0, 0])
self.assertEqual(list(t), [1, 1, 1])
self.assertRaises(StopIteration, next, t)
# check copy, deepcopy, pickle
self.assertEqual(list(copy.copy(takewhile(underten, data))), [1, 3, 5])
self.assertEqual(list(copy.deepcopy(takewhile(underten, data))),
[1, 3, 5])
self.pickletest(takewhile(underten, data))
def test_dropwhile(self):
data = [1, 3, 5, 20, 2, 4, 6, 8]
self.assertEqual(list(dropwhile(underten, data)), [20, 2, 4, 6, 8])
self.assertEqual(list(dropwhile(underten, [])), [])
self.assertRaises(TypeError, dropwhile)
self.assertRaises(TypeError, dropwhile, operator.pow)
self.assertRaises(TypeError, dropwhile, operator.pow, [(4,5)], 'extra')
self.assertRaises(TypeError, next, dropwhile(10, [(4,5)]))
self.assertRaises(ValueError, next, dropwhile(errfunc, [(4,5)]))
# check copy, deepcopy, pickle
self.assertEqual(list(copy.copy(dropwhile(underten, data))), [20, 2, 4, 6, 8])
self.assertEqual(list(copy.deepcopy(dropwhile(underten, data))),
[20, 2, 4, 6, 8])
self.pickletest(dropwhile(underten, data))
def test_tee(self):
n = 200
a, b = tee([]) # test empty iterator
self.assertEqual(list(a), [])
self.assertEqual(list(b), [])
a, b = tee(irange(n)) # test 100% interleaved
self.assertEqual(lzip(a,b), lzip(range(n), range(n)))
a, b = tee(irange(n)) # test 0% interleaved
self.assertEqual(list(a), list(range(n)))
self.assertEqual(list(b), list(range(n)))
a, b = tee(irange(n)) # test dealloc of leading iterator
for i in range(100):
self.assertEqual(next(a), i)
del a
self.assertEqual(list(b), list(range(n)))
a, b = tee(irange(n)) # test dealloc of trailing iterator
for i in range(100):
self.assertEqual(next(a), i)
del b
self.assertEqual(list(a), list(range(100, n)))
for j in range(5): # test randomly interleaved
order = [0]*n + [1]*n
random.shuffle(order)
lists = ([], [])
its = tee(irange(n))
for i in order:
value = next(its[i])
lists[i].append(value)
self.assertEqual(lists[0], list(range(n)))
self.assertEqual(lists[1], list(range(n)))
# test argument format checking
self.assertRaises(TypeError, tee)
self.assertRaises(TypeError, tee, 3)
self.assertRaises(TypeError, tee, [1,2], 'x')
self.assertRaises(TypeError, tee, [1,2], 3, 'x')
# tee object should be instantiable
a, b = tee('abc')
c = type(a)('def')
self.assertEqual(list(c), list('def'))
# test long-lagged and multi-way split
a, b, c = tee(range(2000), 3)
for i in range(100):
self.assertEqual(next(a), i)
self.assertEqual(list(b), list(range(2000)))
self.assertEqual([next(c), next(c)], list(range(2)))
self.assertEqual(list(a), list(range(100,2000)))
self.assertEqual(list(c), list(range(2,2000)))
# test values of n
self.assertRaises(TypeError, tee, 'abc', 'invalid')
self.assertRaises(ValueError, tee, [], -1)
for n in range(5):
result = tee('abc', n)
self.assertEqual(type(result), tuple)
self.assertEqual(len(result), n)
self.assertEqual([list(x) for x in result], [list('abc')]*n)
# tee pass-through to copyable iterator
a, b = tee('abc')
c, d = tee(a)
self.assertTrue(a is c)
# test tee_new
t1, t2 = tee('abc')
tnew = type(t1)
self.assertRaises(TypeError, tnew)
self.assertRaises(TypeError, tnew, 10)
t3 = tnew(t1)
self.assertTrue(list(t1) == list(t2) == list(t3) == list('abc'))
# test that tee objects are weak referencable
a, b = tee(range(10))
p = proxy(a)
self.assertEqual(getattr(p, '__class__'), type(b))
del a
self.assertRaises(ReferenceError, getattr, p, '__class__')
ans = list('abc')
long_ans = list(range(10000))
# check copy
a, b = tee('abc')
self.assertEqual(list(copy.copy(a)), ans)
self.assertEqual(list(copy.copy(b)), ans)
a, b = tee(list(range(10000)))
self.assertEqual(list(copy.copy(a)), long_ans)
self.assertEqual(list(copy.copy(b)), long_ans)
# check partially consumed copy
a, b = tee('abc')
take(2, a)
take(1, b)
self.assertEqual(list(copy.copy(a)), ans[2:])
self.assertEqual(list(copy.copy(b)), ans[1:])
self.assertEqual(list(a), ans[2:])
self.assertEqual(list(b), ans[1:])
a, b = tee(range(10000))
take(100, a)
take(60, b)
self.assertEqual(list(copy.copy(a)), long_ans[100:])
self.assertEqual(list(copy.copy(b)), long_ans[60:])
self.assertEqual(list(a), long_ans[100:])
self.assertEqual(list(b), long_ans[60:])
# check deepcopy
a, b = tee('abc')
self.assertEqual(list(copy.deepcopy(a)), ans)
self.assertEqual(list(copy.deepcopy(b)), ans)
self.assertEqual(list(a), ans)
self.assertEqual(list(b), ans)
a, b = tee(range(10000))
self.assertEqual(list(copy.deepcopy(a)), long_ans)
self.assertEqual(list(copy.deepcopy(b)), long_ans)
self.assertEqual(list(a), long_ans)
self.assertEqual(list(b), long_ans)
# check partially consumed deepcopy
a, b = tee('abc')
take(2, a)
take(1, b)
self.assertEqual(list(copy.deepcopy(a)), ans[2:])
self.assertEqual(list(copy.deepcopy(b)), ans[1:])
self.assertEqual(list(a), ans[2:])
self.assertEqual(list(b), ans[1:])
a, b = tee(range(10000))
take(100, a)
take(60, b)
self.assertEqual(list(copy.deepcopy(a)), long_ans[100:])
self.assertEqual(list(copy.deepcopy(b)), long_ans[60:])
self.assertEqual(list(a), long_ans[100:])
self.assertEqual(list(b), long_ans[60:])
# check pickle
self.pickletest(iter(tee('abc')))
a, b = tee('abc')
self.pickletest(a, compare=ans)
self.pickletest(b, compare=ans)
# Issue 13454: Crash when deleting backward iterator from tee()
def test_tee_del_backward(self):
forward, backward = tee(repeat(None, 20000000))
any(forward) # exhaust the iterator
del backward
def test_StopIteration(self):
self.assertRaises(StopIteration, next, zip())
for f in (chain, cycle, zip, groupby):
self.assertRaises(StopIteration, next, f([]))
self.assertRaises(StopIteration, next, f(StopNow()))
self.assertRaises(StopIteration, next, islice([], None))
self.assertRaises(StopIteration, next, islice(StopNow(), None))
p, q = tee([])
self.assertRaises(StopIteration, next, p)
self.assertRaises(StopIteration, next, q)
p, q = tee(StopNow())
self.assertRaises(StopIteration, next, p)
self.assertRaises(StopIteration, next, q)
self.assertRaises(StopIteration, next, repeat(None, 0))
for f in (filter, filterfalse, map, takewhile, dropwhile, starmap):
self.assertRaises(StopIteration, next, f(lambda x:x, []))
self.assertRaises(StopIteration, next, f(lambda x:x, StopNow()))
class TestExamples(unittest.TestCase):
def test_accumulate(self):
self.assertEqual(list(accumulate([1,2,3,4,5])), [1, 3, 6, 10, 15])
def test_accumulate_reducible(self):
# check copy, deepcopy, pickle
data = [1, 2, 3, 4, 5]
accumulated = [1, 3, 6, 10, 15]
it = accumulate(data)
self.assertEqual(list(pickle.loads(pickle.dumps(it))), accumulated[:])
self.assertEqual(next(it), 1)
self.assertEqual(list(pickle.loads(pickle.dumps(it))), accumulated[1:])
self.assertEqual(list(copy.deepcopy(it)), accumulated[1:])
self.assertEqual(list(copy.copy(it)), accumulated[1:])
def test_chain(self):
self.assertEqual(''.join(chain('ABC', 'DEF')), 'ABCDEF')
def test_chain_from_iterable(self):
self.assertEqual(''.join(chain.from_iterable(['ABC', 'DEF'])), 'ABCDEF')
def test_combinations(self):
self.assertEqual(list(combinations('ABCD', 2)),
[('A','B'), ('A','C'), ('A','D'), ('B','C'), ('B','D'), ('C','D')])
self.assertEqual(list(combinations(range(4), 3)),
[(0,1,2), (0,1,3), (0,2,3), (1,2,3)])
def test_combinations_with_replacement(self):
self.assertEqual(list(combinations_with_replacement('ABC', 2)),
[('A','A'), ('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
def test_compress(self):
self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
def test_count(self):
self.assertEqual(list(islice(count(10), 5)), [10, 11, 12, 13, 14])
def test_cycle(self):
self.assertEqual(list(islice(cycle('ABCD'), 12)), list('ABCDABCDABCD'))
def test_dropwhile(self):
self.assertEqual(list(dropwhile(lambda x: x<5, [1,4,6,4,1])), [6,4,1])
def test_groupby(self):
self.assertEqual([k for k, g in groupby('AAAABBBCCDAABBB')],
list('ABCDAB'))
self.assertEqual([(list(g)) for k, g in groupby('AAAABBBCCD')],
[list('AAAA'), list('BBB'), list('CC'), list('D')])
def test_filter(self):
self.assertEqual(list(filter(lambda x: x%2, range(10))), [1,3,5,7,9])
def test_filterfalse(self):
self.assertEqual(list(filterfalse(lambda x: x%2, range(10))), [0,2,4,6,8])
def test_map(self):
self.assertEqual(list(map(pow, (2,3,10), (5,2,3))), [32, 9, 1000])
def test_islice(self):
self.assertEqual(list(islice('ABCDEFG', 2)), list('AB'))
self.assertEqual(list(islice('ABCDEFG', 2, 4)), list('CD'))
self.assertEqual(list(islice('ABCDEFG', 2, None)), list('CDEFG'))
self.assertEqual(list(islice('ABCDEFG', 0, None, 2)), list('ACEG'))
def test_zip(self):
self.assertEqual(list(zip('ABCD', 'xy')), [('A', 'x'), ('B', 'y')])
def test_zip_longest(self):
self.assertEqual(list(zip_longest('ABCD', 'xy', fillvalue='-')),
[('A', 'x'), ('B', 'y'), ('C', '-'), ('D', '-')])
def test_permutations(self):
self.assertEqual(list(permutations('ABCD', 2)),
list(map(tuple, 'AB AC AD BA BC BD CA CB CD DA DB DC'.split())))
self.assertEqual(list(permutations(range(3))),
[(0,1,2), (0,2,1), (1,0,2), (1,2,0), (2,0,1), (2,1,0)])
def test_product(self):
self.assertEqual(list(product('ABCD', 'xy')),
list(map(tuple, 'Ax Ay Bx By Cx Cy Dx Dy'.split())))
self.assertEqual(list(product(range(2), repeat=3)),
[(0,0,0), (0,0,1), (0,1,0), (0,1,1),
(1,0,0), (1,0,1), (1,1,0), (1,1,1)])
def test_repeat(self):
self.assertEqual(list(repeat(10, 3)), [10, 10, 10])
def test_stapmap(self):
self.assertEqual(list(starmap(pow, [(2,5), (3,2), (10,3)])),
[32, 9, 1000])
def test_takewhile(self):
self.assertEqual(list(takewhile(lambda x: x<5, [1,4,6,4,1])), [1,4])
class TestGC(unittest.TestCase):
def makecycle(self, iterator, container):
container.append(iterator)
next(iterator)
del container, iterator
def test_accumulate(self):
a = []
self.makecycle(accumulate([1,2,a,3]), a)
def test_chain(self):
a = []
self.makecycle(chain(a), a)
def test_chain_from_iterable(self):
a = []
self.makecycle(chain.from_iterable([a]), a)
def test_combinations(self):
a = []
self.makecycle(combinations([1,2,a,3], 3), a)
def test_combinations_with_replacement(self):
a = []
self.makecycle(combinations_with_replacement([1,2,a,3], 3), a)
def test_compress(self):
a = []
self.makecycle(compress('ABCDEF', [1,0,1,0,1,0]), a)
def test_count(self):
a = []
Int = type('Int', (int,), dict(x=a))
self.makecycle(count(Int(0), Int(1)), a)
def test_cycle(self):
a = []
self.makecycle(cycle([a]*2), a)
def test_dropwhile(self):
a = []
self.makecycle(dropwhile(bool, [0, a, a]), a)
def test_groupby(self):
a = []
self.makecycle(groupby([a]*2, lambda x:x), a)
def test_issue2246(self):
# Issue 2246 -- the _grouper iterator was not included in GC
n = 10
keyfunc = lambda x: x
for i, j in groupby(range(n), key=keyfunc):
keyfunc.__dict__.setdefault('x',[]).append(j)
def test_filter(self):
a = []
self.makecycle(filter(lambda x:True, [a]*2), a)
def test_filterfalse(self):
a = []
self.makecycle(filterfalse(lambda x:False, a), a)
def test_zip(self):
a = []
self.makecycle(zip([a]*2, [a]*3), a)
def test_zip_longest(self):
a = []
self.makecycle(zip_longest([a]*2, [a]*3), a)
b = [a, None]
self.makecycle(zip_longest([a]*2, [a]*3, fillvalue=b), a)
def test_map(self):
a = []
self.makecycle(map(lambda x:x, [a]*2), a)
def test_islice(self):
a = []
self.makecycle(islice([a]*2, None), a)
def test_permutations(self):
a = []
self.makecycle(permutations([1,2,a,3], 3), a)
def test_product(self):
a = []
self.makecycle(product([1,2,a,3], repeat=3), a)
def test_repeat(self):
a = []
self.makecycle(repeat(a), a)
def test_starmap(self):
a = []
self.makecycle(starmap(lambda *t: t, [(a,a)]*2), a)
def test_takewhile(self):
a = []
self.makecycle(takewhile(bool, [1, 0, a, a]), a)
def R(seqn):
'Regular generator'
for i in seqn:
yield i
class G:
'Sequence using __getitem__'
def __init__(self, seqn):
self.seqn = seqn
def __getitem__(self, i):
return self.seqn[i]
class I:
'Sequence using iterator protocol'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
def __next__(self):
if self.i >= len(self.seqn): raise StopIteration
v = self.seqn[self.i]
self.i += 1
return v
class Ig:
'Sequence using iterator protocol defined with a generator'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
for val in self.seqn:
yield val
class X:
'Missing __getitem__ and __iter__'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __next__(self):
if self.i >= len(self.seqn): raise StopIteration
v = self.seqn[self.i]
self.i += 1
return v
class N:
'Iterator missing __next__()'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
class E:
'Test propagation of exceptions'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
def __next__(self):
3 // 0
class S:
'Test immediate stop'
def __init__(self, seqn):
pass
def __iter__(self):
return self
def __next__(self):
raise StopIteration
def L(seqn):
'Test multiple tiers of iterators'
return chain(map(lambda x:x, R(Ig(G(seqn)))))
class TestVariousIteratorArgs(unittest.TestCase):
def test_accumulate(self):
s = [1,2,3,4,5]
r = [1,3,6,10,15]
n = len(s)
for g in (G, I, Ig, L, R):
self.assertEqual(list(accumulate(g(s))), r)
self.assertEqual(list(accumulate(S(s))), [])
self.assertRaises(TypeError, accumulate, X(s))
self.assertRaises(TypeError, accumulate, N(s))
self.assertRaises(ZeroDivisionError, list, accumulate(E(s)))
def test_chain(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(chain(g(s))), list(g(s)))
self.assertEqual(list(chain(g(s), g(s))), list(g(s))+list(g(s)))
self.assertRaises(TypeError, list, chain(X(s)))
self.assertRaises(TypeError, list, chain(N(s)))
self.assertRaises(ZeroDivisionError, list, chain(E(s)))
def test_compress(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
n = len(s)
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(compress(g(s), repeat(1))), list(g(s)))
self.assertRaises(TypeError, compress, X(s), repeat(1))
self.assertRaises(TypeError, compress, N(s), repeat(1))
self.assertRaises(ZeroDivisionError, list, compress(E(s), repeat(1)))
def test_product(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
self.assertRaises(TypeError, product, X(s))
self.assertRaises(TypeError, product, N(s))
self.assertRaises(ZeroDivisionError, product, E(s))
def test_cycle(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
tgtlen = len(s) * 3
expected = list(g(s))*3
actual = list(islice(cycle(g(s)), tgtlen))
self.assertEqual(actual, expected)
self.assertRaises(TypeError, cycle, X(s))
self.assertRaises(TypeError, cycle, N(s))
self.assertRaises(ZeroDivisionError, list, cycle(E(s)))
def test_groupby(self):
for s in (range(10), range(0), range(1000), (7,11), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual([k for k, sb in groupby(g(s))], list(g(s)))
self.assertRaises(TypeError, groupby, X(s))
self.assertRaises(TypeError, groupby, N(s))
self.assertRaises(ZeroDivisionError, list, groupby(E(s)))
def test_filter(self):
for s in (range(10), range(0), range(1000), (7,11), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(filter(isEven, g(s))),
[x for x in g(s) if isEven(x)])
self.assertRaises(TypeError, filter, isEven, X(s))
self.assertRaises(TypeError, filter, isEven, N(s))
self.assertRaises(ZeroDivisionError, list, filter(isEven, E(s)))
def test_filterfalse(self):
for s in (range(10), range(0), range(1000), (7,11), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(filterfalse(isEven, g(s))),
[x for x in g(s) if isOdd(x)])
self.assertRaises(TypeError, filterfalse, isEven, X(s))
self.assertRaises(TypeError, filterfalse, isEven, N(s))
self.assertRaises(ZeroDivisionError, list, filterfalse(isEven, E(s)))
def test_zip(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(zip(g(s))), lzip(g(s)))
self.assertEqual(list(zip(g(s), g(s))), lzip(g(s), g(s)))
self.assertRaises(TypeError, zip, X(s))
self.assertRaises(TypeError, zip, N(s))
self.assertRaises(ZeroDivisionError, list, zip(E(s)))
def test_ziplongest(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(zip_longest(g(s))), list(zip(g(s))))
self.assertEqual(list(zip_longest(g(s), g(s))), list(zip(g(s), g(s))))
self.assertRaises(TypeError, zip_longest, X(s))
self.assertRaises(TypeError, zip_longest, N(s))
self.assertRaises(ZeroDivisionError, list, zip_longest(E(s)))
def test_map(self):
for s in (range(10), range(0), range(100), (7,11), range(20,50,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(map(onearg, g(s))),
[onearg(x) for x in g(s)])
self.assertEqual(list(map(operator.pow, g(s), g(s))),
[x**x for x in g(s)])
self.assertRaises(TypeError, map, onearg, X(s))
self.assertRaises(TypeError, map, onearg, N(s))
self.assertRaises(ZeroDivisionError, list, map(onearg, E(s)))
def test_islice(self):
for s in ("12345", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(islice(g(s),1,None,2)), list(g(s))[1::2])
self.assertRaises(TypeError, islice, X(s), 10)
self.assertRaises(TypeError, islice, N(s), 10)
self.assertRaises(ZeroDivisionError, list, islice(E(s), 10))
def test_starmap(self):
for s in (range(10), range(0), range(100), (7,11), range(20,50,5)):
for g in (G, I, Ig, S, L, R):
ss = lzip(s, s)
self.assertEqual(list(starmap(operator.pow, g(ss))),
[x**x for x in g(s)])
self.assertRaises(TypeError, starmap, operator.pow, X(ss))
self.assertRaises(TypeError, starmap, operator.pow, N(ss))
self.assertRaises(ZeroDivisionError, list, starmap(operator.pow, E(ss)))
def test_takewhile(self):
for s in (range(10), range(0), range(1000), (7,11), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
tgt = []
for elem in g(s):
if not isEven(elem): break
tgt.append(elem)
self.assertEqual(list(takewhile(isEven, g(s))), tgt)
self.assertRaises(TypeError, takewhile, isEven, X(s))
self.assertRaises(TypeError, takewhile, isEven, N(s))
self.assertRaises(ZeroDivisionError, list, takewhile(isEven, E(s)))
def test_dropwhile(self):
for s in (range(10), range(0), range(1000), (7,11), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
tgt = []
for elem in g(s):
if not tgt and isOdd(elem): continue
tgt.append(elem)
self.assertEqual(list(dropwhile(isOdd, g(s))), tgt)
self.assertRaises(TypeError, dropwhile, isOdd, X(s))
self.assertRaises(TypeError, dropwhile, isOdd, N(s))
self.assertRaises(ZeroDivisionError, list, dropwhile(isOdd, E(s)))
def test_tee(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
it1, it2 = tee(g(s))
self.assertEqual(list(it1), list(g(s)))
self.assertEqual(list(it2), list(g(s)))
self.assertRaises(TypeError, tee, X(s))
self.assertRaises(TypeError, tee, N(s))
self.assertRaises(ZeroDivisionError, list, tee(E(s))[0])
class LengthTransparency(unittest.TestCase):
def test_repeat(self):
self.assertEqual(operator.length_hint(repeat(None, 50)), 50)
self.assertEqual(operator.length_hint(repeat(None), 12), 12)
class RegressionTests(unittest.TestCase):
def test_sf_793826(self):
# Fix Armin Rigo's successful efforts to wreak havoc
def mutatingtuple(tuple1, f, tuple2):
# this builds a tuple t which is a copy of tuple1,
# then calls f(t), then mutates t to be equal to tuple2
# (needs len(tuple1) == len(tuple2)).
def g(value, first=[1]):
if first:
del first[:]
f(next(z))
return value
items = list(tuple2)
items[1:1] = list(tuple1)
gen = map(g, items)
z = zip(*[gen]*len(tuple1))
next(z)
def f(t):
global T
T = t
first[:] = list(T)
first = []
mutatingtuple((1,2,3), f, (4,5,6))
second = list(T)
self.assertEqual(first, second)
def test_sf_950057(self):
# Make sure that chain() and cycle() catch exceptions immediately
# rather than when shifting between input sources
def gen1():
hist.append(0)
yield 1
hist.append(1)
raise AssertionError
hist.append(2)
def gen2(x):
hist.append(3)
yield 2
hist.append(4)
if x:
raise StopIteration
hist = []
self.assertRaises(AssertionError, list, chain(gen1(), gen2(False)))
self.assertEqual(hist, [0,1])
hist = []
self.assertRaises(AssertionError, list, chain(gen1(), gen2(True)))
self.assertEqual(hist, [0,1])
hist = []
self.assertRaises(AssertionError, list, cycle(gen1()))
self.assertEqual(hist, [0,1])
class SubclassWithKwargsTest(unittest.TestCase):
def test_keywords_in_subclass(self):
# count is not subclassable...
for cls in (repeat, zip, filter, filterfalse, chain, map,
starmap, islice, takewhile, dropwhile, cycle, compress):
class Subclass(cls):
def __init__(self, newarg=None, *args):
cls.__init__(self, *args)
try:
Subclass(newarg=1)
except TypeError as err:
# we expect type errors because of wrong argument count
self.assertNotIn("does not take keyword arguments", err.args[0])
libreftest = """ Doctest for examples in the library reference: libitertools.tex
>>> amounts = [120.15, 764.05, 823.14]
>>> for checknum, amount in zip(count(1200), amounts):
... print('Check %d is for $%.2f' % (checknum, amount))
...
Check 1200 is for $120.15
Check 1201 is for $764.05
Check 1202 is for $823.14
>>> import operator
>>> for cube in map(operator.pow, range(1,4), repeat(3)):
... print(cube)
...
1
8
27
>>> reportlines = ['EuroPython', 'Roster', '', 'alex', '', 'laura', '', 'martin', '', 'walter', '', 'samuele']
>>> for name in islice(reportlines, 3, None, 2):
... print(name.title())
...
Alex
Laura
Martin
Walter
Samuele
>>> from operator import itemgetter
>>> d = dict(a=1, b=2, c=1, d=2, e=1, f=2, g=3)
>>> di = sorted(sorted(d.items()), key=itemgetter(1))
>>> for k, g in groupby(di, itemgetter(1)):
... print(k, list(map(itemgetter(0), g)))
...
1 ['a', 'c', 'e']
2 ['b', 'd', 'f']
3 ['g']
# Find runs of consecutive numbers using groupby. The key to the solution
# is differencing with a range so that consecutive numbers all appear in
# same group.
>>> data = [ 1, 4,5,6, 10, 15,16,17,18, 22, 25,26,27,28]
>>> for k, g in groupby(enumerate(data), lambda t:t[0]-t[1]):
... print(list(map(operator.itemgetter(1), g)))
...
[1]
[4, 5, 6]
[10]
[15, 16, 17, 18]
[22]
[25, 26, 27, 28]
>>> def take(n, iterable):
... "Return first n items of the iterable as a list"
... return list(islice(iterable, n))
>>> def enumerate(iterable, start=0):
... return zip(count(start), iterable)
>>> def tabulate(function, start=0):
... "Return function(0), function(1), ..."
... return map(function, count(start))
>>> def nth(iterable, n, default=None):
... "Returns the nth item or a default value"
... return next(islice(iterable, n, None), default)
>>> def quantify(iterable, pred=bool):
... "Count how many times the predicate is true"
... return sum(map(pred, iterable))
>>> def padnone(iterable):
... "Returns the sequence elements and then returns None indefinitely"
... return chain(iterable, repeat(None))
>>> def ncycles(iterable, n):
... "Returns the sequence elements n times"
... return chain(*repeat(iterable, n))
>>> def dotproduct(vec1, vec2):
... return sum(map(operator.mul, vec1, vec2))
>>> def flatten(listOfLists):
... return list(chain.from_iterable(listOfLists))
>>> def repeatfunc(func, times=None, *args):
... "Repeat calls to func with specified arguments."
... " Example: repeatfunc(random.random)"
... if times is None:
... return starmap(func, repeat(args))
... else:
... return starmap(func, repeat(args, times))
>>> def pairwise(iterable):
... "s -> (s0,s1), (s1,s2), (s2, s3), ..."
... a, b = tee(iterable)
... try:
... next(b)
... except StopIteration:
... pass
... return zip(a, b)
>>> def grouper(n, iterable, fillvalue=None):
... "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
... args = [iter(iterable)] * n
... return zip_longest(*args, fillvalue=fillvalue)
>>> def roundrobin(*iterables):
... "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
... # Recipe credited to George Sakkis
... pending = len(iterables)
... nexts = cycle(iter(it).__next__ for it in iterables)
... while pending:
... try:
... for next in nexts:
... yield next()
... except StopIteration:
... pending -= 1
... nexts = cycle(islice(nexts, pending))
>>> def powerset(iterable):
... "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
... s = list(iterable)
... return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))
>>> def unique_everseen(iterable, key=None):
... "List unique elements, preserving order. Remember all elements ever seen."
... # unique_everseen('AAAABBBCCDAABBB') --> A B C D
... # unique_everseen('ABBCcAD', str.lower) --> A B C D
... seen = set()
... seen_add = seen.add
... if key is None:
... for element in iterable:
... if element not in seen:
... seen_add(element)
... yield element
... else:
... for element in iterable:
... k = key(element)
... if k not in seen:
... seen_add(k)
... yield element
>>> def unique_justseen(iterable, key=None):
... "List unique elements, preserving order. Remember only the element just seen."
... # unique_justseen('AAAABBBCCDAABBB') --> A B C D A B
... # unique_justseen('ABBCcAD', str.lower) --> A B C A D
... return map(next, map(itemgetter(1), groupby(iterable, key)))
This is not part of the examples but it tests to make sure the definitions
perform as purported.
>>> take(10, count())
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(enumerate('abc'))
[(0, 'a'), (1, 'b'), (2, 'c')]
>>> list(islice(tabulate(lambda x: 2*x), 4))
[0, 2, 4, 6]
>>> nth('abcde', 3)
'd'
>>> nth('abcde', 9) is None
True
>>> quantify(range(99), lambda x: x%2==0)
50
>>> a = [[1, 2, 3], [4, 5, 6]]
>>> flatten(a)
[1, 2, 3, 4, 5, 6]
>>> list(repeatfunc(pow, 5, 2, 3))
[8, 8, 8, 8, 8]
>>> import random
>>> take(5, map(int, repeatfunc(random.random)))
[0, 0, 0, 0, 0]
>>> list(pairwise('abcd'))
[('a', 'b'), ('b', 'c'), ('c', 'd')]
>>> list(pairwise([]))
[]
>>> list(pairwise('a'))
[]
>>> list(islice(padnone('abc'), 0, 6))
['a', 'b', 'c', None, None, None]
>>> list(ncycles('abc', 3))
['a', 'b', 'c', 'a', 'b', 'c', 'a', 'b', 'c']
>>> dotproduct([1,2,3], [4,5,6])
32
>>> list(grouper(3, 'abcdefg', 'x'))
[('a', 'b', 'c'), ('d', 'e', 'f'), ('g', 'x', 'x')]
>>> list(roundrobin('abc', 'd', 'ef'))
['a', 'd', 'e', 'b', 'f', 'c']
>>> list(powerset([1,2,3]))
[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)]
>>> all(len(list(powerset(range(n)))) == 2**n for n in range(18))
True
>>> list(powerset('abcde')) == sorted(sorted(set(powerset('abcde'))), key=len)
True
>>> list(unique_everseen('AAAABBBCCDAABBB'))
['A', 'B', 'C', 'D']
>>> list(unique_everseen('ABBCcAD', str.lower))
['A', 'B', 'C', 'D']
>>> list(unique_justseen('AAAABBBCCDAABBB'))
['A', 'B', 'C', 'D', 'A', 'B']
>>> list(unique_justseen('ABBCcAD', str.lower))
['A', 'B', 'C', 'A', 'D']
"""
__test__ = {'libreftest' : libreftest}
def test_main(verbose=None):
test_classes = (TestBasicOps, TestVariousIteratorArgs, TestGC,
RegressionTests, LengthTransparency,
SubclassWithKwargsTest, TestExamples)
support.run_unittest(*test_classes)
# verify reference counting
if verbose and hasattr(sys, "gettotalrefcount"):
import gc
counts = [None] * 5
for i in range(len(counts)):
support.run_unittest(*test_classes)
gc.collect()
counts[i] = sys.gettotalrefcount()
print(counts)
# doctest the examples in the library reference
support.run_doctest(sys.modules[__name__], verbose)
if __name__ == "__main__":
test_main(verbose=True)
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