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54f22ed30b
who writes: Here is batch 2, as a big collection of CVS context diffs. Along with moving comments into docstrings, i've added a couple of missing docstrings and attempted to make sure more module docstrings begin with a one-line summary. I did not add docstrings to the methods in profile.py for fear of upsetting any careful optimizations there, though i did move class documentation into class docstrings. The convention i'm using is to leave credits/version/copyright type of stuff in # comments, and move the rest of the descriptive stuff about module usage into module docstrings. Hope this is okay.
142 lines
4.4 KiB
Python
142 lines
4.4 KiB
Python
"""General floating point formatting functions.
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Functions:
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fix(x, digits_behind)
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sci(x, digits_behind)
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Each takes a number or a string and a number of digits as arguments.
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Parameters:
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x: number to be formatted; or a string resembling a number
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digits_behind: number of digits behind the decimal point
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"""
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import re
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# Compiled regular expression to "decode" a number
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decoder = re.compile(r'^([-+]?)0*(\d*)((?:\.\d*)?)(([eE][-+]?\d+)?)$')
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# \0 the whole thing
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# \1 leading sign or empty
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# \2 digits left of decimal point
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# \3 fraction (empty or begins with point)
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# \4 exponent part (empty or begins with 'e' or 'E')
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try:
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class NotANumber(ValueError):
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pass
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except TypeError:
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NotANumber = 'fpformat.NotANumber'
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def extract(s):
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"""Return (sign, intpart, fraction, expo) or raise an exception:
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sign is '+' or '-'
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intpart is 0 or more digits beginning with a nonzero
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fraction is 0 or more digits
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expo is an integer"""
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res = decoder.match(s)
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if res is None: raise NotANumber, s
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sign, intpart, fraction, exppart = res.group(1,2,3,4)
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if sign == '+': sign = ''
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if fraction: fraction = fraction[1:]
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if exppart: expo = int(exppart[1:])
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else: expo = 0
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return sign, intpart, fraction, expo
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def unexpo(intpart, fraction, expo):
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"""Remove the exponent by changing intpart and fraction."""
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if expo > 0: # Move the point left
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f = len(fraction)
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intpart, fraction = intpart + fraction[:expo], fraction[expo:]
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if expo > f:
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intpart = intpart + '0'*(expo-f)
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elif expo < 0: # Move the point right
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i = len(intpart)
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intpart, fraction = intpart[:expo], intpart[expo:] + fraction
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if expo < -i:
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fraction = '0'*(-expo-i) + fraction
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return intpart, fraction
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def roundfrac(intpart, fraction, digs):
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"""Round or extend the fraction to size digs."""
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f = len(fraction)
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if f <= digs:
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return intpart, fraction + '0'*(digs-f)
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i = len(intpart)
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if i+digs < 0:
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return '0'*-digs, ''
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total = intpart + fraction
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nextdigit = total[i+digs]
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if nextdigit >= '5': # Hard case: increment last digit, may have carry!
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n = i + digs - 1
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while n >= 0:
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if total[n] != '9': break
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n = n-1
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else:
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total = '0' + total
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i = i+1
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n = 0
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total = total[:n] + chr(ord(total[n]) + 1) + '0'*(len(total)-n-1)
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intpart, fraction = total[:i], total[i:]
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if digs >= 0:
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return intpart, fraction[:digs]
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else:
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return intpart[:digs] + '0'*-digs, ''
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def fix(x, digs):
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"""Format x as [-]ddd.ddd with 'digs' digits after the point
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and at least one digit before.
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If digs <= 0, the point is suppressed."""
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if type(x) != type(''): x = `x`
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try:
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sign, intpart, fraction, expo = extract(x)
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except NotANumber:
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return x
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intpart, fraction = unexpo(intpart, fraction, expo)
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intpart, fraction = roundfrac(intpart, fraction, digs)
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while intpart and intpart[0] == '0': intpart = intpart[1:]
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if intpart == '': intpart = '0'
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if digs > 0: return sign + intpart + '.' + fraction
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else: return sign + intpart
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def sci(x, digs):
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"""Format x as [-]d.dddE[+-]ddd with 'digs' digits after the point
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and exactly one digit before.
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If digs is <= 0, one digit is kept and the point is suppressed."""
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if type(x) != type(''): x = `x`
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sign, intpart, fraction, expo = extract(x)
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if not intpart:
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while fraction and fraction[0] == '0':
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fraction = fraction[1:]
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expo = expo - 1
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if fraction:
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intpart, fraction = fraction[0], fraction[1:]
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expo = expo - 1
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else:
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intpart = '0'
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else:
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expo = expo + len(intpart) - 1
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intpart, fraction = intpart[0], intpart[1:] + fraction
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digs = max(0, digs)
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intpart, fraction = roundfrac(intpart, fraction, digs)
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if len(intpart) > 1:
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intpart, fraction, expo = \
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intpart[0], intpart[1:] + fraction[:-1], \
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expo + len(intpart) - 1
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s = sign + intpart
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if digs > 0: s = s + '.' + fraction
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e = `abs(expo)`
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e = '0'*(3-len(e)) + e
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if expo < 0: e = '-' + e
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else: e = '+' + e
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return s + 'e' + e
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def test():
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"""Interactive test run."""
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try:
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while 1:
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x, digs = input('Enter (x, digs): ')
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print x, fix(x, digs), sci(x, digs)
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except (EOFError, KeyboardInterrupt):
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pass
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