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What's the notation for any number in re? Like if I'm searching a string for any number, positive or negative. I've been using \d+ but that can't find 0 or -1
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\d (digit) matches any single digit (same as [0-9] ). The uppercase counterpart \D (non-digit) matches any single character that is not a digit (same as [^0-9] ). \s (space) matches any single whitespace (same as [ \t\n\r\f] , blank, tab, newline, carriage-return and form-feed).
(wildcard character) match anything, including line breaks. Throw in an * (asterisk), and it will match everything. Read more. \s (whitespace metacharacter) will match any whitespace character (space; tab; line break; ...), and \S (opposite of \s ) will match anything that is not a whitespace character.
Summary: To extract numbers from a given string in Python you can use one of the following methods: Use the regex module. Use split() and append() functions on a list. Use a List Comprehension with isdigit() and split() functions.
Searching for positive, negative, and/or decimals, you could use [+-]?\d+(?:\.\d+)?
>>> nums = re.compile(r"[+-]?\d+(?:\.\d+)?")
>>> nums.search("0.123").group(0)
'0.123'
>>> nums.search("+0.123").group(0)
'+0.123'
>>> nums.search("123").group(0)
'123'
>>> nums.search("-123").group(0)
'-123'
>>> nums.search("1").group(0)
'1'
This isn't very smart about leading/trailing zeros, of course:
>>> nums.search("0001.20000").group(0)
'0001.20000'
Edit: Corrected the above regex to find single-digit numbers.
If you wanted to add support for exponential form, try [+-]?\d+(?:\.\d+)?(?:[eE][+-]?\d+)?:
>>> nums2 = re.compile(r"[+-]?\d+(?:\.\d+)?(?:[eE][+-]?\d+)?")
>>> nums2.search("-1.23E+45").group(0)
'-1.23E+45'
>>> nums2.search("0.1e-456").group(0)
'0.1e-456'
>>> nums2.search("1e99").group(0)
'1e99'
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