| 1 | n/a | """General floating point formatting functions. |
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| 2 | n/a | |
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| 3 | n/a | Functions: |
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| 4 | n/a | fix(x, digits_behind) |
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| 5 | n/a | sci(x, digits_behind) |
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| 6 | n/a | |
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| 7 | n/a | Each takes a number or a string and a number of digits as arguments. |
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| 8 | n/a | |
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| 9 | n/a | Parameters: |
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| 10 | n/a | x: number to be formatted; or a string resembling a number |
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| 11 | n/a | digits_behind: number of digits behind the decimal point |
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| 12 | 1 | """ |
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| 13 | 1 | from warnings import warnpy3k |
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| 14 | 1 | warnpy3k("the fpformat module has been removed in Python 3.0", stacklevel=2) |
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| 15 | 1 | del warnpy3k |
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| 16 | n/a | |
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| 17 | 1 | import re |
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| 18 | n/a | |
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| 19 | 1 | __all__ = ["fix","sci","NotANumber"] |
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| 20 | n/a | |
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| 21 | n/a | # Compiled regular expression to "decode" a number |
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| 22 | 1 | decoder = re.compile(r'^([-+]?)0*(\d*)((?:\.\d*)?)(([eE][-+]?\d+)?)$') |
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| 23 | n/a | # \0 the whole thing |
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| 24 | n/a | # \1 leading sign or empty |
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| 25 | n/a | # \2 digits left of decimal point |
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| 26 | n/a | # \3 fraction (empty or begins with point) |
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| 27 | n/a | # \4 exponent part (empty or begins with 'e' or 'E') |
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| 28 | n/a | |
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| 29 | 1 | try: |
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| 30 | 2 | class NotANumber(ValueError): |
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| 31 | 1 | pass |
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| 32 | 0 | except TypeError: |
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| 33 | 0 | NotANumber = 'fpformat.NotANumber' |
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| 34 | n/a | |
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| 35 | 1 | def extract(s): |
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| 36 | n/a | """Return (sign, intpart, fraction, expo) or raise an exception: |
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| 37 | n/a | sign is '+' or '-' |
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| 38 | n/a | intpart is 0 or more digits beginning with a nonzero |
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| 39 | n/a | fraction is 0 or more digits |
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| 40 | n/a | expo is an integer""" |
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| 41 | 342 | res = decoder.match(s) |
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| 42 | 342 | if res is None: raise NotANumber, s |
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| 43 | 340 | sign, intpart, fraction, exppart = res.group(1,2,3,4) |
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| 44 | 340 | if sign == '+': sign = '' |
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| 45 | 340 | if fraction: fraction = fraction[1:] |
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| 46 | 340 | if exppart: expo = int(exppart[1:]) |
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| 47 | 312 | else: expo = 0 |
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| 48 | 340 | return sign, intpart, fraction, expo |
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| 49 | n/a | |
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| 50 | 1 | def unexpo(intpart, fraction, expo): |
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| 51 | n/a | """Remove the exponent by changing intpart and fraction.""" |
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| 52 | 170 | if expo > 0: # Move the point left |
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| 53 | 0 | f = len(fraction) |
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| 54 | 0 | intpart, fraction = intpart + fraction[:expo], fraction[expo:] |
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| 55 | 0 | if expo > f: |
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| 56 | 0 | intpart = intpart + '0'*(expo-f) |
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| 57 | 170 | elif expo < 0: # Move the point right |
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| 58 | 14 | i = len(intpart) |
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| 59 | 14 | intpart, fraction = intpart[:expo], intpart[expo:] + fraction |
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| 60 | 14 | if expo < -i: |
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| 61 | 14 | fraction = '0'*(-expo-i) + fraction |
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| 62 | 170 | return intpart, fraction |
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| 63 | n/a | |
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| 64 | 1 | def roundfrac(intpart, fraction, digs): |
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| 65 | n/a | """Round or extend the fraction to size digs.""" |
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| 66 | 340 | f = len(fraction) |
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| 67 | 340 | if f <= digs: |
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| 68 | 199 | return intpart, fraction + '0'*(digs-f) |
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| 69 | 141 | i = len(intpart) |
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| 70 | 141 | if i+digs < 0: |
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| 71 | 0 | return '0'*-digs, '' |
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| 72 | 141 | total = intpart + fraction |
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| 73 | 141 | nextdigit = total[i+digs] |
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| 74 | 141 | if nextdigit >= '5': # Hard case: increment last digit, may have carry! |
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| 75 | 0 | n = i + digs - 1 |
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| 76 | 0 | while n >= 0: |
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| 77 | 0 | if total[n] != '9': break |
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| 78 | 0 | n = n-1 |
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| 79 | n/a | else: |
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| 80 | 0 | total = '0' + total |
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| 81 | 0 | i = i+1 |
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| 82 | 0 | n = 0 |
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| 83 | 0 | total = total[:n] + chr(ord(total[n]) + 1) + '0'*(len(total)-n-1) |
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| 84 | 0 | intpart, fraction = total[:i], total[i:] |
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| 85 | 141 | if digs >= 0: |
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| 86 | 141 | return intpart, fraction[:digs] |
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| 87 | n/a | else: |
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| 88 | 0 | return intpart[:digs] + '0'*-digs, '' |
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| 89 | n/a | |
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| 90 | 1 | def fix(x, digs): |
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| 91 | n/a | """Format x as [-]ddd.ddd with 'digs' digits after the point |
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| 92 | n/a | and at least one digit before. |
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| 93 | n/a | If digs <= 0, the point is suppressed.""" |
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| 94 | 171 | if type(x) != type(''): x = repr(x) |
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| 95 | 171 | try: |
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| 96 | 171 | sign, intpart, fraction, expo = extract(x) |
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| 97 | 1 | except NotANumber: |
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| 98 | 1 | return x |
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| 99 | 170 | intpart, fraction = unexpo(intpart, fraction, expo) |
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| 100 | 170 | intpart, fraction = roundfrac(intpart, fraction, digs) |
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| 101 | 170 | while intpart and intpart[0] == '0': intpart = intpart[1:] |
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| 102 | 170 | if intpart == '': intpart = '0' |
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| 103 | 170 | if digs > 0: return sign + intpart + '.' + fraction |
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| 104 | 24 | else: return sign + intpart |
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| 105 | n/a | |
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| 106 | 1 | def sci(x, digs): |
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| 107 | n/a | """Format x as [-]d.dddE[+-]ddd with 'digs' digits after the point |
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| 108 | n/a | and exactly one digit before. |
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| 109 | n/a | If digs is <= 0, one digit is kept and the point is suppressed.""" |
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| 110 | 171 | if type(x) != type(''): x = repr(x) |
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| 111 | 171 | sign, intpart, fraction, expo = extract(x) |
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| 112 | 170 | if not intpart: |
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| 113 | 182 | while fraction and fraction[0] == '0': |
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| 114 | 112 | fraction = fraction[1:] |
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| 115 | 112 | expo = expo - 1 |
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| 116 | 70 | if fraction: |
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| 117 | 70 | intpart, fraction = fraction[0], fraction[1:] |
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| 118 | 70 | expo = expo - 1 |
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| 119 | n/a | else: |
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| 120 | 0 | intpart = '0' |
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| 121 | n/a | else: |
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| 122 | 100 | expo = expo + len(intpart) - 1 |
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| 123 | 100 | intpart, fraction = intpart[0], intpart[1:] + fraction |
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| 124 | 170 | digs = max(0, digs) |
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| 125 | 170 | intpart, fraction = roundfrac(intpart, fraction, digs) |
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| 126 | 170 | if len(intpart) > 1: |
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| 127 | n/a | intpart, fraction, expo = \ |
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| 128 | 0 | intpart[0], intpart[1:] + fraction[:-1], \ |
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| 129 | 0 | expo + len(intpart) - 1 |
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| 130 | 170 | s = sign + intpart |
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| 131 | 170 | if digs > 0: s = s + '.' + fraction |
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| 132 | 170 | e = repr(abs(expo)) |
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| 133 | 170 | e = '0'*(3-len(e)) + e |
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| 134 | 170 | if expo < 0: e = '-' + e |
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| 135 | 86 | else: e = '+' + e |
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| 136 | 170 | return s + 'e' + e |
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| 137 | n/a | |
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| 138 | 1 | def test(): |
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| 139 | n/a | """Interactive test run.""" |
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| 140 | 0 | try: |
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| 141 | 0 | while 1: |
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| 142 | 0 | x, digs = input('Enter (x, digs): ') |
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| 143 | 0 | print x, fix(x, digs), sci(x, digs) |
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| 144 | 0 | except (EOFError, KeyboardInterrupt): |
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| 145 | 0 | pass |
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