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106 lines
3.5 KiB
Python
106 lines
3.5 KiB
Python
"""Unittests for heapq."""
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from heapq import heappush, heappop, heapify, heapreplace, nlargest, nsmallest
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import random
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import unittest
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from test import test_support
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def heapiter(heap):
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# An iterator returning a heap's elements, smallest-first.
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try:
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while 1:
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yield heappop(heap)
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except IndexError:
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pass
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class TestHeap(unittest.TestCase):
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def test_push_pop(self):
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# 1) Push 256 random numbers and pop them off, verifying all's OK.
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heap = []
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data = []
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self.check_invariant(heap)
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for i in range(256):
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item = random.random()
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data.append(item)
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heappush(heap, item)
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self.check_invariant(heap)
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results = []
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while heap:
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item = heappop(heap)
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self.check_invariant(heap)
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results.append(item)
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data_sorted = data[:]
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data_sorted.sort()
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self.assertEqual(data_sorted, results)
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# 2) Check that the invariant holds for a sorted array
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self.check_invariant(results)
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def check_invariant(self, heap):
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# Check the heap invariant.
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for pos, item in enumerate(heap):
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if pos: # pos 0 has no parent
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parentpos = (pos-1) >> 1
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self.assert_(heap[parentpos] <= item)
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def test_heapify(self):
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for size in range(30):
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heap = [random.random() for dummy in range(size)]
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heapify(heap)
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self.check_invariant(heap)
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def test_naive_nbest(self):
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data = [random.randrange(2000) for i in range(1000)]
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heap = []
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for item in data:
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heappush(heap, item)
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if len(heap) > 10:
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heappop(heap)
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heap.sort()
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self.assertEqual(heap, sorted(data)[-10:])
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def test_nbest(self):
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# Less-naive "N-best" algorithm, much faster (if len(data) is big
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# enough <wink>) than sorting all of data. However, if we had a max
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# heap instead of a min heap, it could go faster still via
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# heapify'ing all of data (linear time), then doing 10 heappops
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# (10 log-time steps).
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data = [random.randrange(2000) for i in range(1000)]
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heap = data[:10]
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heapify(heap)
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for item in data[10:]:
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if item > heap[0]: # this gets rarer the longer we run
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heapreplace(heap, item)
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self.assertEqual(list(heapiter(heap)), sorted(data)[-10:])
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def test_heapsort(self):
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# Exercise everything with repeated heapsort checks
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for trial in xrange(100):
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size = random.randrange(50)
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data = [random.randrange(25) for i in range(size)]
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if trial & 1: # Half of the time, use heapify
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heap = data[:]
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heapify(heap)
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else: # The rest of the time, use heappush
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heap = []
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for item in data:
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heappush(heap, item)
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heap_sorted = [heappop(heap) for i in range(size)]
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self.assertEqual(heap_sorted, sorted(data))
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def test_nsmallest(self):
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data = [random.randrange(2000) for i in range(1000)]
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self.assertEqual(nsmallest(data, 400), sorted(data)[:400])
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def test_largest(self):
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data = [random.randrange(2000) for i in range(1000)]
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self.assertEqual(nlargest(data, 400), sorted(data, reverse=True)[:400])
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def test_main():
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test_support.run_unittest(TestHeap)
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if __name__ == "__main__":
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test_main()
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