[Python] Obtaining diff for multiple columns in pandas

i have a pandas dataframe with multiple columns (on which I am computing the cumulative value).

I would like to get the incremental value for the same now.

This is my current dataset:

Gender Cubic_Cap Branch UWYear yhat_all
M 1000 A 2015 19
M 1000 A 2015 20
M 1000 A 2015 26
M 1000 A 2015 30
F 1500 B 2016 1
F 1500 B 2016 25
F 1500 B 2016 36
F 1500 B 2016 49


My desired result is:

yhat_incremental
0
1
6
4
1
24
11
13


I've tried the following methods (but to no avail):

all_c1['incremental_yhat'] = all_c1.groupby(rating_factors)['yhat_all'].diff().fillna(all_c1['yhat_all'])


I've also tried this:

all_c1['incremental_yhat'] = all_c1['yhat_all'].shift().where(all_c1[rating_factors].eq(all_c1[rating_factors].shift()))


Is there any other methods I can use to obtain this?

Continue reading...