如何在findall()函数返回的列表上运行sub()函数？

Question

我在尝试替换字符串中的文本。首先，我必须使用findall()来收集几个不同的事件，然后我必须用一个特定的字符串替换它们。

以下是问题所在：

1. 编写一个正则表达式，该表达式将在search_string中找到所有出现的正则表达式b.正则表达式c.正则:表达式d正则表达式
2. 将正则表达式赋值给名为模式的变量。
3. 使用re包中的sub()方法将“模式”的所有出现替换为“替换”
4. 将sub()方法的结果分配给一个名为replace_result的变量
5. 输出到控制台replace_results

这是我的代码：

import re
search_string = '''This is a string to search for a regular expression 
like regular expression or regular-expression or regular:expression or 
regular&expression'''
pattern = re.findall('regular.expression', search_string)
substitution = 'regular expression'
replace_results = re.sub('regular.expression', 'regular expression', 
search_string)
print(replace_results)

因此，我知道find将返回一个列表，这将导致TypeError: unhashable：' list‘。我可以用“regular.expression”代替sub，但这并不能真正解决问题。做这件事的正确方法是什么？

Answer 1

这个问题根本没有要求您使用re.findall。您应该使用re.sub搜索模式，然后用substitution替换匹配。

import re
search_string = 'This is a string to search for a regular expression like regular expression or regular-expression or regular:expression or regular&expression'
pattern = 'regular[ -:^]expression'
substitution = 'substitution'
replace_result = re.sub(pattern, substitution, search_string)
print(replace_result)

这一产出如下：

This is a string to search for a substitution like substitution or substitution or substitution or substitution

Answer 2

​

import re

#The string to search for the regular expression occurrence (This is provided to the student)
search_string='''This is a string to search for a regular expression like regular expression or 
regular-expression or regular:expression or regular&expression'''

#1.  Write a regular expression that will find all occurrances of:
#    a.  regular expression
#    b.  regular-expression
#    c.  regular:expression
#    d.  regular&expression
#    in search_string
text=re.compile(r'regular.\w+')
##2.  Assign the regular expression to a variable named pattern
pattern=text
#The string to use for substitution (This is provided to the student)

substitution="regular expression"

#3.  Using the sub() method from the re package substitute all occurrences of the 'pattern' with 'substitution'
result = re.sub(pattern, substitution, search_string)
#4.   Assign the outcome of the sub() method to a variable called replace_result
replace_result=result
#5.  Output to the console replace_results
print(replace_result)

​

​

import re

#The string to search for the regular expression occurrence (This is provided to the student)
search_string='''This is a string to search for a regular expression like regular expression or 
regular-expression or regular:expression or regular&expression'''

#1.  Write a regular expression that will find all occurrances of:
#    a.  regular expression
#    b.  regular-expression
#    c.  regular:expression
#    d.  regular&expression
#    in search_string
text=re.compile(r'regular.\w+')
##2.  Assign the regular expression to a variable named pattern
pattern=text
#The string to use for substitution (This is provided to the student)

substitution="regular expression"

#3.  Using the sub() method from the re package substitute all occurrences of the 'pattern' with 'substitution'
result = re.sub(pattern, substitution, search_string)
#4.   Assign the outcome of the sub() method to a variable called replace_result
replace_result=result
#5.  Output to the console replace_results
print(replace_result)

​