根据另一个数据框的列值创建一个数据框

Question

I have a dataframe as 20000 X 50. Two of the columns are Date and Time (represented as hour). Remaining columns have observations of some parameters during the time. What I am trying to achieve is create a new dataframe which averages all the remaining column values for every 3 hours per day and creates a an ID columns for this which can be numbers from 1 to 8. Each representing 3 hour range. I have enclosed an image of the source and what should be result. Any help is very much appreciated. Data

Answer 1

Use groupby by column Date and column Hour created by sub by 1 and floordiv with add with aggregate mean :

df['Hour'] = df['Hour'].sub(1).floordiv(3).add(1)
df = df.groupby(['Date', 'Hour'], as_index=False).mean()
print (df)
         Date  Hour      col1      col2      col3
0  05/01/2018     1  5.333333  5.333333  7.666667
1  05/01/2018     2  6.000000  6.000000  4.000000
2  06/01/2018     1  4.000000  6.333333  7.000000
3  06/01/2018     3  6.000000  6.000000  3.666667

Detail:

print (df['Hour'].sub(1).floordiv(3).add(1))
0    1
1    1
2    1
3    2
4    1
5    1
6    1
7    3
8    3
9    3
Name: Hour, dtype: int64