Question

我试图使用正则表达式替换字符串中特定单词的一个实例，其中需要替换的单词至少出现两次。例如，我有以下内容：

The NOUN is ADJECTIVE and is completely different from the NOUN.

到目前为止，我有：

content = 'The NOUN is ADJECTIVE and is completely different from the NOUN.'   

noun = input('Enter a noun: ')
adj = input('Enter an adjective: ')
noun_1 = input('Enter another noun: ')

names_regex_noun = re.compile(r'NOUN')
content = names_regex_noun.sub(noun, content)
names_regex_adj = re.compile(r'ADJECTIVE')
content = names_regex_adj.sub(adj, content)
names_regex_noun_1 = re.compile(r'NOUN')
content = names_regex_noun_1.sub(noun_1, content) 
print(content)

我遇到的问题是，在使用names_regex_noun.sub(noun, content)时，它正在替换NOUN中content的两个实例。我只想替换第一个NOUN并保持noun_1不受影响，以便{{1}}替换它。

Answer 1

对于这样的简单表达式，您只需将str.replace()与指定的count一起使用：

>>> content = 'The NOUN is ADJECTIVE and is completely different from the NOUN.'
>>> noun = 'bird'
>>> content.replace('NOUN', noun, 1)
'The bird is ADJECTIVE and is completely different from the NOUN.'

Answer 2

x="abc abc abc"
print re.sub(r"abc\s*","",x,count=1)

输出：abc abc

re.sub(pattern, repl, string, count=0, flags=0)` 

use `count=1`

正则表达式：仅替换一次

2 个答案: