从 pandas DataFrame 中的文本中提取子字符串作为新列

Question

我有一个列表'words'我要数在下面

word_list = ['one','three']

我在 pandas 数据框中有一列，下面有文本。

TEXT                                       |
-------------------------------------------|
"Perhaps she'll be the one for me."        |
"Is it two or one?"                        |
"Mayhaps it be three afterall..."          |
"Three times and it's a charm."            |
"One fish, two fish, red fish, blue fish." |
"There's only one cat in the hat."         |
"One does not simply code into pandas."    |
"Two nights later..."                      |
"Quoth the Raven... nevermore."            |

期望的输出如下所示，它保留原始文本列，但只将 word_list 中的单词提取到新列

TEXT                                       | EXTRACT
-------------------------------------------|---------------
"Perhaps she'll be the one for me."        | one
"Is it two or one?"                        | one
"Mayhaps it be three afterall..."          | three
"Three times and it's a charm."            | three
"One fish, two fish, red fish, blue fish." | one
"There's only one cat in the hat."         | one
"One does not simply code into pandas."    | one
"Two nights later..."                      | 
"Quoth the Raven... nevermore."            |

在 Python 2.7 中有没有办法做到这一点？

Answer 1

使用str.extract:

df['EXTRACT'] = df.TEXT.str.extract('({})'.format('|'.join(word_list)), 
                        flags=re.IGNORECASE, expand=False).str.lower().fillna('')
df['EXTRACT']

0      one
1      one
2    three
3    three
4      one
5      one
6      one
7         
8         
Name: EXTRACT, dtype: object

word_list 中的每个单词由正则表达式分隔符 | 连接，然后传递给 str.extract 进行正则表达式模式匹配。

打开 re.IGNORECASE 开关以进行不区分大小写的比较，结果匹配项将小写以匹配您的预期输出。