PANDAS: Sum value of column grouped by other column in dataframe

Question

First I am sorry if this is a recurrent question, but the way I tried to phrase it I did not find any repeats of it.

I have a data frame that among its columns it has one with date values and other that is a one hot encoding of the presence of an event:

date          event
20-11-2019     1
20-11-2019     1
12-3-2018      0

I am trying to find a way to obtain the number of events on each of those dates.

I tried to navigate around group by but got nowhere useful. Can anyone help me?

Does this answer your question? [Pandas group-by and sum](https://stackoverflow.com/questions/39922986/pandas-group-by-and-sum) — Mayank Porwal, Nov 16 '20 at 18:48

score 2 · Answer 1 · answered Nov 16 '20 at 15:28

2

Try groupby and sum

out = df.groupby('date',as_index=False).sum()
Out[75]: 
         date  event
0   12-3-2018      0
1  20-11-2019      2

answered Nov 16 '20 at 15:28

BENY

score 0 · Answer 2 · answered Nov 16 '20 at 15:29

0

does data.groupby('date')[['event']].sum() does what you want?

answered Nov 16 '20 at 15:29

gaut

2 Answers2