如果您很好奇,这是由于(如您所料)的Fraction
正则表达式fractions.py
:
_RATIONAL_FORMAT = re.compile(r"""
\A\s* # optional whitespace at the start, then
(?P<sign>[-+]?) # an optional sign, then
(?=\d|\.\d) # lookahead for digit or .digit
(?P<num>\d*) # numerator (possibly empty)
(?: # followed by an optional
/(?P<denom>\d+) # / and denominator
| # or
\.(?P<decimal>\d*) # decimal point and fractional part
)?
\s*\Z # and optional whitespace to finish
""", re.VERBOSE)
这与科学计数法中的浮点数不匹配。这在 Python 2.7 中有所改变(以下来自 3.1,因为我没有安装 2.7):
_RATIONAL_FORMAT = re.compile(r"""
\A\s* # optional whitespace at the start, then
(?P<sign>[-+]?) # an optional sign, then
(?=\d|\.\d) # lookahead for digit or .digit
(?P<num>\d*) # numerator (possibly empty)
(?: # followed by
(?:/(?P<denom>\d+))? # an optional denominator
| # or
(?:\.(?P<decimal>\d*))? # an optional fractional part
(?:E(?P<exp>[-+]?\d+))? # and optional exponent
)
\s*\Z # and optional whitespace to finish
""", re.VERBOSE | re.IGNORECASE)