Is there any way to calculate the weekly data in python?-CodePudding

I have issue with dataframe. I would like to get the results within starting of the week minus the ending of the week. Is there any way to do it?

Week Number	Position	Desired Results	Operation
1	2
1	2
1	2	0	2-2
2	4
2	6
3	7	3	7-4
3	12
3	14
3	15	3	15-12

CodePudding user response：

Try groupby with transform:

df['Desired'] = df.groupby('Week Number')['Position'].transform(lambda x: x.iloc[-1] - x.iloc[0])

And now:

>>> df
   Week Number  Position  Desired
0            1         2        0
1            1         2        0
2            1         2        0
3            2         4        3
4            2         6        3
5            2         7        3
6            3        12        3
7            3        14        3
8            3        15        3
>>>

Or assign to variable first:

group = df.groupby('Week Number')['Position']
df['Desired'] = group.transform('last') - group.transform('first')

Edit:

To not have duplicates, try:

df['Desired'] = df.groupby('Week Number')['Position'].transform(lambda x: [''] * (len(x) - 1)   [x.iloc[-1] - x.iloc[0]])

And now:

>>> df
   Week Number  Position Desired
0            1         2        
1            1         2        
2            1         2       0
3            2         4        
4            2         6        
5            2         7       3
6            3        12        
7            3        14        
8            3        15       3
>>>