diff options
Diffstat (limited to 'Lib/fpformat.py')
| -rw-r--r-- | Lib/fpformat.py | 206 |
1 files changed, 103 insertions, 103 deletions
diff --git a/Lib/fpformat.py b/Lib/fpformat.py index 523f3ce..31debba 100644 --- a/Lib/fpformat.py +++ b/Lib/fpformat.py @@ -22,120 +22,120 @@ decoder = re.compile(r'^([-+]?)0*(\d*)((?:\.\d*)?)(([eE][-+]?\d+)?)$') # \4 exponent part (empty or begins with 'e' or 'E') try: - class NotANumber(ValueError): - pass + class NotANumber(ValueError): + pass except TypeError: - NotANumber = 'fpformat.NotANumber' + NotANumber = 'fpformat.NotANumber' -# Return (sign, intpart, fraction, expo) or raise an exception: -# sign is '+' or '-' -# intpart is 0 or more digits beginning with a nonzero -# fraction is 0 or more digits -# expo is an integer def extract(s): - res = decoder.match(s) - if res is None: raise NotANumber, s - sign, intpart, fraction, exppart = res.group(1,2,3,4) - if sign == '+': sign = '' - if fraction: fraction = fraction[1:] - if exppart: expo = int(exppart[1:]) - else: expo = 0 - return sign, intpart, fraction, expo + """Return (sign, intpart, fraction, expo) or raise an exception: + sign is '+' or '-' + intpart is 0 or more digits beginning with a nonzero + fraction is 0 or more digits + expo is an integer""" + res = decoder.match(s) + if res is None: raise NotANumber, s + sign, intpart, fraction, exppart = res.group(1,2,3,4) + if sign == '+': sign = '' + if fraction: fraction = fraction[1:] + if exppart: expo = int(exppart[1:]) + else: expo = 0 + return sign, intpart, fraction, expo -# Remove the exponent by changing intpart and fraction def unexpo(intpart, fraction, expo): - if expo > 0: # Move the point left - f = len(fraction) - intpart, fraction = intpart + fraction[:expo], fraction[expo:] - if expo > f: - intpart = intpart + '0'*(expo-f) - elif expo < 0: # Move the point right - i = len(intpart) - intpart, fraction = intpart[:expo], intpart[expo:] + fraction - if expo < -i: - fraction = '0'*(-expo-i) + fraction - return intpart, fraction + """Remove the exponent by changing intpart and fraction.""" + if expo > 0: # Move the point left + f = len(fraction) + intpart, fraction = intpart + fraction[:expo], fraction[expo:] + if expo > f: + intpart = intpart + '0'*(expo-f) + elif expo < 0: # Move the point right + i = len(intpart) + intpart, fraction = intpart[:expo], intpart[expo:] + fraction + if expo < -i: + fraction = '0'*(-expo-i) + fraction + return intpart, fraction -# Round or extend the fraction to size digs def roundfrac(intpart, fraction, digs): - f = len(fraction) - if f <= digs: - return intpart, fraction + '0'*(digs-f) - i = len(intpart) - if i+digs < 0: - return '0'*-digs, '' - total = intpart + fraction - nextdigit = total[i+digs] - if nextdigit >= '5': # Hard case: increment last digit, may have carry! - n = i + digs - 1 - while n >= 0: - if total[n] != '9': break - n = n-1 - else: - total = '0' + total - i = i+1 - n = 0 - total = total[:n] + chr(ord(total[n]) + 1) + '0'*(len(total)-n-1) - intpart, fraction = total[:i], total[i:] - if digs >= 0: - return intpart, fraction[:digs] - else: - return intpart[:digs] + '0'*-digs, '' + """Round or extend the fraction to size digs.""" + f = len(fraction) + if f <= digs: + return intpart, fraction + '0'*(digs-f) + i = len(intpart) + if i+digs < 0: + return '0'*-digs, '' + total = intpart + fraction + nextdigit = total[i+digs] + if nextdigit >= '5': # Hard case: increment last digit, may have carry! + n = i + digs - 1 + while n >= 0: + if total[n] != '9': break + n = n-1 + else: + total = '0' + total + i = i+1 + n = 0 + total = total[:n] + chr(ord(total[n]) + 1) + '0'*(len(total)-n-1) + intpart, fraction = total[:i], total[i:] + if digs >= 0: + return intpart, fraction[:digs] + else: + return intpart[:digs] + '0'*-digs, '' -# Format x as [-]ddd.ddd with 'digs' digits after the point -# and at least one digit before. -# If digs <= 0, the point is suppressed. def fix(x, digs): - if type(x) != type(''): x = `x` - try: - sign, intpart, fraction, expo = extract(x) - except NotANumber: - return x - intpart, fraction = unexpo(intpart, fraction, expo) - intpart, fraction = roundfrac(intpart, fraction, digs) - while intpart and intpart[0] == '0': intpart = intpart[1:] - if intpart == '': intpart = '0' - if digs > 0: return sign + intpart + '.' + fraction - else: return sign + intpart + """Format x as [-]ddd.ddd with 'digs' digits after the point + and at least one digit before. + If digs <= 0, the point is suppressed.""" + if type(x) != type(''): x = `x` + try: + sign, intpart, fraction, expo = extract(x) + except NotANumber: + return x + intpart, fraction = unexpo(intpart, fraction, expo) + intpart, fraction = roundfrac(intpart, fraction, digs) + while intpart and intpart[0] == '0': intpart = intpart[1:] + if intpart == '': intpart = '0' + if digs > 0: return sign + intpart + '.' + fraction + else: return sign + intpart -# Format x as [-]d.dddE[+-]ddd with 'digs' digits after the point -# and exactly one digit before. -# If digs is <= 0, one digit is kept and the point is suppressed. def sci(x, digs): - if type(x) != type(''): x = `x` - sign, intpart, fraction, expo = extract(x) - if not intpart: - while fraction and fraction[0] == '0': - fraction = fraction[1:] - expo = expo - 1 - if fraction: - intpart, fraction = fraction[0], fraction[1:] - expo = expo - 1 - else: - intpart = '0' - else: - expo = expo + len(intpart) - 1 - intpart, fraction = intpart[0], intpart[1:] + fraction - digs = max(0, digs) - intpart, fraction = roundfrac(intpart, fraction, digs) - if len(intpart) > 1: - intpart, fraction, expo = \ - intpart[0], intpart[1:] + fraction[:-1], \ - expo + len(intpart) - 1 - s = sign + intpart - if digs > 0: s = s + '.' + fraction - e = `abs(expo)` - e = '0'*(3-len(e)) + e - if expo < 0: e = '-' + e - else: e = '+' + e - return s + 'e' + e + """Format x as [-]d.dddE[+-]ddd with 'digs' digits after the point + and exactly one digit before. + If digs is <= 0, one digit is kept and the point is suppressed.""" + if type(x) != type(''): x = `x` + sign, intpart, fraction, expo = extract(x) + if not intpart: + while fraction and fraction[0] == '0': + fraction = fraction[1:] + expo = expo - 1 + if fraction: + intpart, fraction = fraction[0], fraction[1:] + expo = expo - 1 + else: + intpart = '0' + else: + expo = expo + len(intpart) - 1 + intpart, fraction = intpart[0], intpart[1:] + fraction + digs = max(0, digs) + intpart, fraction = roundfrac(intpart, fraction, digs) + if len(intpart) > 1: + intpart, fraction, expo = \ + intpart[0], intpart[1:] + fraction[:-1], \ + expo + len(intpart) - 1 + s = sign + intpart + if digs > 0: s = s + '.' + fraction + e = `abs(expo)` + e = '0'*(3-len(e)) + e + if expo < 0: e = '-' + e + else: e = '+' + e + return s + 'e' + e -# Interactive test run def test(): - try: - while 1: - x, digs = input('Enter (x, digs): ') - print x, fix(x, digs), sci(x, digs) - except (EOFError, KeyboardInterrupt): - pass + """Interactive test run.""" + try: + while 1: + x, digs = input('Enter (x, digs): ') + print x, fix(x, digs), sci(x, digs) + except (EOFError, KeyboardInterrupt): + pass |