How to calculate average values by group of other value type?

user_13174189 0
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I have a dataframe:

id     day      action_type
1       0        upload     
1       0        upload 
1       0        upload 
1       1        upload 
1       1        upload 
2       0        upload 
2       0        upload 
2       1        upload

How to change my query to get table with unique days in column day and average number "upload" action_type among all id's. So desired result must look like this:

day     avg_num_action
0        2.5 
1        1.5

It is 2.5, because (3+2)/2 (3 uploads of id:1 and 2 uploads for id:2). same for 1.5

How to do that in pandas?

pandas dataframe python-3.x python
3 Answers

Try crosstab

pd.crosstab(df.id, df.day).mean()
user_79645270

Assuming df is your dataframe:

df.groupby(['day', 'id']).count().groupby('day').mean()
user_114770310

With a groupby, and unstack:

result = df.groupby(['id', 'day']).size().unstack('day').mean()
result 
day
0    2.5
1    1.5
dtype: float64

To match your expected output,add reset_index:

result.reset_index(name = 'avg_num_action')
 
   day  avg_num_action
0    0             2.5
1    1             1.5
user_71757130
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