Pandas: Group two columns based on value in another column

问题

I'm pretty new to python/pandas and I have a dataframe that looks something like this:

 id         name        color
id_1        alex        blue
id_2        james       yellow
id_1        sara        black
id_4        dave        pink
id_4        lin         grey
id_2        aly         red

I want to group by id and get the values in the other two columns as a list:

  id           name              color
id_1        [alex,sara]       [blue,black]
id_2        [james,aly]       [yellow,red]
id_4        [dave,lin]        [pink,grey]

Is there an easy way to do that?

回答1:

Use groupby and agg by custom function with tolist:

df = df.groupby('id').agg(lambda x: x.tolist())
print (df)
              name          color
id                               
id_1  [alex, sara]  [blue, black]
id_2  [james, aly]  [yellow, red]
id_4   [dave, lin]   [pink, grey]

来源：https://stackoverflow.com/questions/45436938/pandas-group-two-columns-based-on-value-in-another-column