pandas groupby add and average at the same time

Question

I have a data frame with a list of processes and the time they took as follows

I would like to get the following result

I know how to use gorupby in order to get ONE but only one of those columns. And this is the way I solve the problem

# the data
ps    = ['p1','p2','p3','p4','p2','p2','p3','p6','p2','p4','p5','p6']
times = [20,10,2,3,4,5,6,3,4,5,6,7]
processes = pd.DataFrame({'ps':ps,'time':times})

# the series
dfsum   = processes.groupby('PROCESS')['TIME'].sum()
dfcount = processes.groupby('PROCESS')['TIME'].count()

# "building" the df result
frame = { 'total_time': dfsum, 'total_nr': dfcount} 
dfresult = pd.DataFrame(frame)
dfresult['average']= dfresult['total_time']/dfresult['total_nr']
dfresult

but how to get the desired df without having to compose it column by column? For me this method is not "pandonic" enough (nor pythonic)

Have a look at [named aggregation](https://pandas.pydata.org/pandas-docs/stable/user_guide/groupby.html#named-aggregation): ``processes.groupby("ps").agg(total_time=("time", "sum"),avg_time=("time", "size"))`` — sammywemmy, Jan 18 '21 at 20:46

score 3 · Answer 1 · answered Jan 18 '21 at 20:46

Try groupby.agg():

df.groupby('PROCESS')['TIME'].agg(['sum','mean','count'])

Output for the sample data:

    sum   mean  count
ps                   
p1   20  20.00      1
p2   23   5.75      4
p3    8   4.00      2
p4    8   4.00      2
p5    6   6.00      1
p6   10   5.00      2

score 3 · Accepted Answer · edited Sep 02 '23 at 11:13

3

processes.groupby('ps').agg(TOTAL_TIME=('time','sum'),AVERAGE=('time','mean'),NRTIMES=('time','size'))

edited Sep 02 '23 at 11:13

creanion

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answered Jan 18 '21 at 20:47

wwnde

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pandas groupby add and average at the same time

2 Answers2