Hello
I know it is not a problem per se but I think there should be some pandas built in solution for this problem, as no simple function exists for this.
It is largely discussed here with various ideas (https://stackoverflow.com/questions/12680754/split-pandas-dataframe-string-entry-to-separate-rows) but they are quite tricky actually, not using built in things but hacking normal behavior for the most part.

I believe that could use some strategy drawn from the reindexing/filling functions, but as I am not a Pandas specialist, I am not sure this would use the most efficient function to perform this task.

Let's say we have

df var1 var2 0 a,b,c x 1 d,e,f y 

df.desired_function("var1") var1 var2 0 a x 1 b x 2 c x 3 d y 4 e y 5 f y 

Best regards