拆分列并分配给同一数据框

Question

I have a dataset for movies recommendation and want to separate the genre feature into two genre columns(genre_1,genre_2),and assign it into the same dataframe. The column has all the genres together and separates them with '|'. If it is not having two genres then genre_1 need to be assigned to genre_2.

What is the best way to do it?

     movieId      title                                genres
0       1         Toy Story (1995)                     Adventure|Animation|Children|Comedy|Fantasy
1       2         Jumanji (1995)                       Adventure|Children|Fantasy
2       3         Grumpier Old Men (1995)              Comedy|Romance
3       4         Waiting to Exhale (1995)             Comedy|Drama|Romance
4       5         Father of the Bride Part II (1995)   Comedy

Thanks

Answer 1

The split function will take apart that string when given '|' as the separator. Pro tip: keeping the genres as a list will work much better than keeping them as two variables; you can iterate over the list instead of naming each variable, and if some flick is counted as more than two genres, you're home free.

Answer 2

Like suggested in the comment, you should provide an example of the output you're looking for, it's not completely clear from your question.

Anyway, you can split the genre list into separate columns using:

df['genres'].str.split('|',expand=True)

eg:

df['genres']
Out[13]: 
0    Adventure|Animation|Children|Comedy|Fantasy
1                     Adventure|Children|Fantasy
2                                 Comedy|Romance
3                           Comedy|Drama|Romance
4                                         Comedy


df['genres'].str.split('|',expand=True)
Out[14]: 
           0          1         2       3        4
0  Adventure  Animation  Children  Comedy  Fantasy
1  Adventure   Children   Fantasy    None     None
2     Comedy    Romance      None    None     None
3     Comedy      Drama   Romance    None     None
4     Comedy       None      None    None     None

.str tells pandas to treat that column as a string, and then you have most Python string manipulation methods available.

expand = True causes each "split" to be stored in a separate column.

Answer 3

Thanks for the replies, i have solved this problem in the following way. (got help from another friend.)

    df['genre_1'],df['genre_2'],df['genre_3'] = df.genres.str.split('|',2).str
    df['genre_2'] = df['genre_2'].fillna(df['genre_1'])
    df= df.drop('genre_3',axis=1)