Python Pandas: Groupby Sum AND Concatenate Strings

Question

Sample Pandas Dataframe:

ID Name COMMENT1 COMMENT2 NUM
1  dan  hi       hello    1
1  dan  you      friend   2
3  jon  yeah     nope     3
2  jon  dog      cat      .5
3  jon  yes      no       .1

I am trying to create a dataframe that groups by ID and NAME that concatenates COMMENT1 and COMMENT2 that also sums NUM.

This is what I'm looking for:

ID Name COMMENT1     COMMENT2        NUM
1  dan  hi you       hello friend    3
3  jon  yeah yes     nope no         3.1
2  jon  dog          cat             .5

I tried using this:

input_df = input_df.groupby(['ID', 'NAME', 'COMMENT1', 'COMMENT2']).sum().reset_index()

But it doesn't work.

If I use this:

input_df = input_df.groupby(['ID']).sum().reset_index()

It sums the NUM column but leaves out all other columns.

Answer 1

Let us make it into one line

df.groupby(['ID','Name'],as_index=False).agg(lambda x : x.sum() if x.dtype=='float64' else ' '.join(x))
Out[1510]: 
   ID Name  COMMENT1      COMMENT2  NUM
0   1  dan    hi you  hello friend  3.0
1   2  jon       dog           cat  0.5
2   3  jon  yeah yes       nope no  3.1