正则表达式以提取数字和字符串

Question

I need to extract some data from a string, the string is something like this fixed-string-<number>-<string> . Fixed string is always the same, I need to extact number and its string.

In python 3.5, I'm using the next regular expression

str = 'initial-string/fixed-string-124-jeff-thompson'
result = re.match('fixed-string-([0-9]*)-(.*)', str)
print (result)

But result is always None value, I checked the string and it's well formed.

What am I doing wrong?

Update

testing = 'first-string/fixed-string-123-jeff-thompson'
pattern = r'fixed-string-(\d+)-(.*)'

result = re.match(pattern, testing)

I tested this, and the code still returns me None .

Thanks you.

Answer 1

The following works:

> s = 'fixed-string-345-abc'
> re.match(r'fixed-string-(\d+)-(.+)')  # if num and string shouldn't be empty
# re.match(r'fixed-string-(\d*)-(.*)')
> m.group(1, 2)
('345', 'abc')

Answer 2

This works, too:

import re
s = 'fixed-string-123-456'
result = re.findall('(?<=fixed-string-)(\d+)-(.*)', s)
if result:
    print (result[0])
#('123', '456')

https://ideone.com/4RRwff

Answer 3

You are using re.match, which tries to match the pattern at the beginning (ie from the first character) of your string. Here, "initial-string/" prevents it from matching.

You can either include "initial-string/" in your pattern, or use re.search which will match starting at any position in your string.

Note that it's also better to use raw strings (r'my string with \\backslahes') to avoid the potential need for escaping in your pattern.

string = 'initial-string/fixed-string-124-jeff-thompson'
result = re.search(r'fixed-string-([0-9]*)-(.*)', str)
result.groups()
# ('124', 'jeff-thompson')

or

result = re.match(r'initial-string/fixed-string-([0-9]*)-(.*)', str)
result.groups()
# ('124', 'jeff-thompson')