Question
The source string is:
# Python 3.4.3
s = r'abc123d, hello 3.1415926, this is my book'
and here is my pattern:
pattern = r'-?[0-9]+(\\.[0-9]*)?|-?\\.[0-9]+'
however, re.search can give me correct result:
m = re.search(pattern, s)
print(m) # output: <_sre.SRE_Match object; span=(3, 6), match='123'>
re.findall just dump out an empty list:
L = re.findall(pattern, s)
print(L) # output: ['', '', '']
why can't re.findall give me the expected list:
['123', '3.1415926']
Answer
s = r'abc123d, hello 3.1415926, this is my book'
print re.findall(r'-?[0-9]+(?:\.[0-9]*)?|-?\.[0-9]+',s)
You dont need to escape twice when you are using raw mode.
Output:['123', '3.1415926']
Also the return type will be a list of strings. If you want return type as
integers and floats use map
import re,ast
s = r'abc123d, hello 3.1415926, this is my book'
print map(ast.literal_eval,re.findall(r'-?[0-9]+(?:\.[0-9]*)?|-?\.[0-9]+',s))
Output: [123, 3.1415926]
