从数据框中提取与列表进行比较的字符串 [英] Extract string from a dataframe comparing to a list

问题描述

我正在尝试从pandas数据帧中的DF中提取字符串，并且源字符串在必须与之匹配的列表中.我尝试使用df.str.extract(list1)，但出现了无法哈希类型的错误，我想我将列表与DF比较的方式不正确

I am trying to extract strings from a DF in pandas dataframe and the source strings are in a list from which I have to match. I tried using a df.str.extract(list1) but i got an error of unhashable types i guess i the way I compare the list to the DF is not correct

来自

Col 1   Col 2
1       The date
2       Three has come
3       Mail Sent
4       Done Deal

收件人

Col 1   Col 2           Col 3 
1       The date        NaN
2       Three has come  Three has
3       Mail Sent        Mail
4       Done Deal        Done

我的列表如下

List1 = ['Three has' , 'Mail' , 'Done' , 'Game' , 'Time has come']

推荐答案

您可以使用

You can use extract with join all values in List by | what means or in regex:

List1 = ['Three has' , 'Mail' , 'Done' , 'Game' , 'Time has come']
df['Col 3'] = df['Col 2'].str.extract("(" + "|".join(List1) +")", expand=False)
print (df)
   Col 1           Col 2      Col 3
0      1        The date        NaN
1      2  Three has come  Three has
2      3       Mail Sent       Mail
3      4       Done Deal       Done

另一种解决方案:

List1 = ['Three has' , 'Mail' , 'Done' , 'Game' , 'Time has come']

df['Col 3'] = df['Col 2'].apply(lambda x: ''.join([L for L in List1 if L in x]))
df['Col 3'] = df['Col 3'].mask(df['Col 3'] == '')
print (df)
   Col 1           Col 2      Col 3
0      1        The date        NaN
1      2  Three has come  Three has
2      3       Mail Sent       Mail
3      4       Done Deal       Done

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