如何从另一个数据框更新一个数据框的特定列

Question

the first dataframe is:

   data_date cookie_type   dau  next_dau  dau_7  dau_15
0   20181006    avg(0-d)  2288       NaN    NaN     NaN
1   20181006    avg(e-f)  2284       NaN    NaN     NaN
2   20181007    avg(e-f)  2296       NaN    NaN     NaN

the second dataframe is :

  data_date cookie_type  next_dau
0  20181006    avg(e-f)       908
1  20181006    avg(0-d)       904

how to update the first dataframe's next_dau from the second one i have tried combine_first and fillna, they seem not support multi-index:

cols = ['data_date', 'cookie_type']

    if (frame1 is not None and not frame1.empty):
        frame1.set_index(cols)
        print(frame1)
        print(next_day_dau)
        frame1.combine_first(next_day_dau.set_index(cols))
        frame1.combine_first(dau_7.set_index(cols))
        frame1.combine_first(dau_15.set_index(cols))

finally i solved this problem with help from "tianhua liao":

            frame1.index = frame1.data_date.astype(str) + frame1.cookie_type
            next_day_dau.index = next_day_dau.data_date.astype(str) + next_day_dau.cookie_type
            dau_7.index = dau_7.data_date.astype(str) + dau_7.cookie_type
            dau_15.index = dau_15.data_date.astype(str) + dau_15.cookie_type
            # get_index
            next_day_dau_idx = frame1.index.isin(next_day_dau.index)
            dau_7_idx = frame1.index.isin(dau_7.index)
            dau_15_idx = frame1.index.isin(dau_15.index)
            #
            if any(next_day_dau_idx):
                frame1.loc[next_day_dau_idx, "next_dau"] = next_day_dau.next_dau
            if any(dau_7_idx):
                frame1.loc[dau_7_idx, "dau_7"] = dau_7.dau_7
            if any(dau_15_idx):
                frame1.loc[dau_15_idx, "dau_15"] = dau_15.dau_15

Answer 1

Multi-index is a complicated one.

Here is a simple way to solve it.

frame1.index = frame1.data_date.astype(str) + frame1.cookie_type
frame2.index = frame2.data_date.astype(str) + frame2.cookie_type

frame1.loc[frame2.index,"next_dau"] = frame2.next_dau

After processing completed, you could remove the index.