Python的正則表達式無法取代整行

Question

我想替換我的文本行中的特定區域。 我用蟒的正則表達式的子語法

import re 
str='WALL = "W101"' 
s=re.sub('WALL = "(.*)"','100',str) 
print(s) 

它只我期望整行WALL = "100"

Answer 1

考慮附加捕獲組用於第一子串打印100但 ：

str = 'WALL = "W101"' 
s = re.sub(r'^(WALL =\s*)"(.*)"', r'\1"100"', str) 
print(s) 

輸出：

WALL = "100" 

個

\1指向第一個捕獲組withing正則表達式

Answer 2

你可以使用lookbehind：

import re 
str = 'WALL = "W101"' 
s = re.sub(r'(?<=WALL = ")[^"]+', '100', str) 
print(s) 

說明：

(?<=  : start lookbehind, makes sure we have the following before the match 
    WALL = " : literally 
)   : end lookbehind 
[^"]+  : 1 or more character that is NOT a double quote