在python中将字符串转换为小写的简单方法

Question

我有一个文本如下。你知道吗

mytext = "This is AVGs_ABB and NMN_ABB and most importantly GFD_ABB This is so important that you have to CLEAN  the lab everyday"

我想把它转换成小写，除了有_ABB的单词。你知道吗

所以，我的输出应该如下所示。你知道吗

    mytext = "this is AVGs_ABB and NMN_ABB and most importantly GFD_ABB this is so important that you have to clean  the lab everyday"

我现在的代码如下。你知道吗

splits = mytext.split()
newtext = []
for item in splits:
   if not '_ABB' in item:
        item = item.lower()
        newtext.append(item)
   else:
        newtext.append(item)

然而，我想知道是否有任何简单的方法可以做到这一点，可能在一行？你知道吗

Answer 1

您可以使用一行代码将字符串拆分为单词，用str.endswith()检查单词，然后将单词重新连接在一起：

' '.join(w if w.endswith('_ABB') else w.lower() for w in mytext.split())
# 'this is AVGs_ABB and NMN_ABB and most importantly GFD_ABB this is so important that you have to clean the lab everyday'

当然，如果'_ABB'实际上可以出现在单词的任何地方，而不仅仅是在词尾，那么使用in运算符而不是str.endswith()。你知道吗

Answer 2

下面是另一个可能的（不优雅的）一行：

mytext = "This is AVGs_ABB and NMN_ABB and most importantly GFD_ABB This is so important that you have to CLEAN  the lab everyday"

print(' '.join(map(lambda x : x if '_ABB' in x else x.lower(), mytext.split())))

输出：

this is AVGs_ABB and NMN_ABB and most importantly GFD_ABB this is so important that you have to clean the lab everyday

注意：这假设您的文本将只按空格分隔单词，因此split()在这里就足够了。如果文本中包含",!."等标点符号，则需要使用regex来拆分单词。你知道吗

Answer 3

扩展的正则表达式方法：

import  re

mytext = "This is AVGs_ABB and NMN_ABB and most importantly GFD_ABB This is so important that you have to CLEAN  the lab everyday"
result = re.sub(r'\b((?!_ABB)\S)+\b', lambda m: m.group().lower(), mytext)

print(result)

输出：

this is AVGs_ABB and NMN_ABB and most importantly GFD_ABB this is so important that you have to clean  the lab everyday

---

详情：

• \b-词边界
• (?!_ABB)-lookahead否定断言，确保给定的模式不匹配
• \S-非空白字符
• \b((?!_ABB)\S)+\b-整个模式匹配不包含子串的单词_ABB