python - 与列表相比，从数据框中提取字符串

Question

我正在尝试从 pandas 数据框中的 DF 中提取字符串，源字符串位于我必须匹配的列表中。我尝试使用 df.str.extract(list1) 但我收到不可散列类型的错误我猜我将列表与 DF 进行比较的方式不正确

From

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

To

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 list 如下

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

Answer 1

您可以使用 extract通过| join List 中的所有值是什么意思 or 在regex 中:

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