Python – 不区分大小写的字符串替换

给定字符串单词。任务是编写一个Python程序，用给定的字符串替换给定的单词，而不管大小写。

例子：

Input : test_str = “gfg is BeSt”, repl = “good”, subs = “best”

Output : gfg is good

Explanation : BeSt is replaced by “good” ignoring cases.

Input : test_str = “gfg is BeSt”, repl = “better”, subs = “best”

Output : gfg is better

Explanation : BeSt is replaced by “better” ignoring cases.

方法 #1：使用 re.IGNORECASE + re.escape() + re.sub()

在此，正则表达式的 sub() 用于执行替换和 IGNORECASE 任务，忽略大小写并执行不区分大小写的替换。

Python3

# Python3 code to demonstrate working of
# Case insensitive Replace
# Using re.IGNORECASE + re.escape() + re.sub()
import re
  
# initializing string
test_str = "gfg is BeSt"
  
# printing original string
print("The original string is : " + str(test_str))
  
# initializing replace string 
repl = "good"
  
# initializing substring to be replaced 
subs = "best"
  
# re.IGNORECASE ignoring cases 
# compilation step to escape the word for all cases
compiled = re.compile(re.escape(subs), re.IGNORECASE)
res = compiled.sub(repl, test_str)
          
# printing result
print("Replaced String : " + str(res))

输出

The original string is : gfg is BeSt
Replaced String : gfg is good

方法 #2：使用 sub() + lambda + escape()

使用特定的忽略大小写正则表达式也可以解决这个问题。休息一下，如果字符串存在转义字符，则使用 lambda函数来处理转义字符。

蟒蛇3

# Python3 code to demonstrate working of
# Case insensitive Replace
# Using sub() + lambda + escape() 
import re
  
# initializing string
test_str = "gfg is BeSt"
  
# printing original string
print("The original string is : " + str(test_str))
  
# initializing replace string 
repl = "good"
  
# initializing substring to be replaced 
subs = "best"
  
# regex used for ignoring cases
res = re.sub('(?i)'+re.escape(subs), lambda m: repl, test_str)
          
# printing result
print("Replaced String : " + str(res))

输出

The original string is : gfg is BeSt
Replaced String : gfg is good