正则表达式搜索以从字符串中提取浮点数.Python

问题描述

import re

sequence = 'i have -0.03 dollars in my hand'

m = re.search('(have )(-w[.]+)( dollarsw+)',sequence)

print m.group(0)
print m.group(1)
print m.group(2)

Looking for a way to extract text between two occurrences. In this case, the format is 'i have ' followed by - floats and then followed by ' dollarsw+'

How do i use re.search to extract this float ? Why don't the groups work this way ? I know there's something I can tweak to get it to work with these groups. any help would be greatly appreciated

I thought I could use groups with paranthesis but i got an eror

解决方案

-w[.]+ does not match -0.03 because [.] matches . literally because . is inside the [...].

w after dollars also prevent the pattern to match the sequence. There no word character after dollars.

Use (-?d+.d+) as pattern:

import re

sequence = 'i have -0.03 dollars in my hand'

m = re.search(r'(have )(-?d+.d+)( dollars)', sequence)

print m.group(1) # captured group start from `1`.
print m.group(2) 
print m.group(3)

BTW, captured group numbers start from 1. (group(0) returns entire matched string)