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Adding a column thats result of difference in consecutive rows in pandas  


Sathish Kumar
Member Moderator
Joined: 4 months ago
Posts: 1203
24/03/2021 11:47 am  

Lets say I have a dataframe like this

    A   B

0   a   b

1   c   d

2   e   f 

3   g   h

0,1,2,3 are times, a, c, e, g is one time series and b, d, f, h is another time series. I need to be able to add two columns to the orignal dataframe which is got by computing the differences of consecutive rows for certain columns.

So i need something like this

    A   B   dA

0   a   b  (a-c)

1   c   d  (c-e)

2   e   f  (e-g)

3   g   h   Nan

I saw something called diff on the dataframe/series but that does it slightly differently as in first element will become Nan.