[Python] Take cumsum of each row in polars

E.g. if I have

import polars as pl
df = pl.DataFrame({'a': [1,2,3], 'b': [4,5,6]})


how would I find the cumulative sum of each row?

Expected output:

a b
0 1 5
1 2 7
2 3 9


Here's the equivalent in pandas:

>>> import pandas as pd
>>> pd.DataFrame({'a': [1,2,3], 'b': [4,5,6]}).cumsum(axis=1)
a b
0 1 5
1 2 7
2 3 9


but I can't figure out how to do it in polars

Continue reading...