检查Pandas DataFrame列中的字符串是否在字符串列表中

Question

如果我有这样的框架

frame = pd.DataFrame({'a' : ['the cat is blue', 'the sky is green', 'the dog is black']})

我想检查这些行中是否包含某个单词，我只需要这样做。

frame['b'] = frame.a.str.contains("dog") | frame.a.str.contains("cat") | frame.a.str.contains("fish")

frame['b'] 输出：

True
False
True

如果我决定列出一个清单

mylist =['dog', 'cat', 'fish']

如何检查列表中的行是否包含某个单词？

Answer 1

frame = pd.DataFrame({'a' : ['the cat is blue', 'the sky is green', 'the dog is black']})

frame
                  a
0   the cat is blue
1  the sky is green
2  the dog is black

该str.contains方法接受正则表达式模式：

mylist = ['dog', 'cat', 'fish']
pattern = '|'.join(mylist)

pattern
'dog|cat|fish'

frame.a.str.contains(pattern)
0     True
1    False
2     True
Name: a, dtype: bool

由于支持正则表达式模式，因此您还可以嵌入标志：

frame = pd.DataFrame({'a' : ['Cat Mr. Nibbles is blue', 'the sky is green', 'the dog is black']})

frame
                     a
0  Cat Mr. Nibbles is blue
1         the sky is green
2         the dog is black

pattern = '|'.join([f'(?i){animal}' for animal in mylist])  # python 3.6+

pattern
'(?i)dog|(?i)cat|(?i)fish'

frame.a.str.contains(pattern)
0     True  # Because of the (?i) flag, 'Cat' is also matched to 'cat'
1    False
2     True