exploding multiple csv fields in python

Question

I have an excel file with 200 rows, 2 of which have comma separated values in them. If I output them to tab-separated, it would look like this:

col1  col2    col3
a     b,c     d,e
f     g,h     i,j

I need to explode to get a dataframe like this, exploding 200 rows into ~4,000:

col1  col2  col3
a     b     d
a     b     e
a     c     d
a     c     e
f     g     i
f     g     j
f     h     i
f     h     j

I don't see any explode functionality in pandas and haven't been able to figure out how to do this having the columns of comma-separated values uneven in length - not sure how split would work here.

Help me stack-overflow, you're my only hope. Thanks!

Answer 1

Use itertools.product to get all combinations between col2 and col3, and then convert them into separate columns

from itertools import product
df.set_index('col1')\
  .apply(lambda x: pd.Series(list(product(x.col2.split(','),x.col3.split(',')))),axis=1)\
  .stack()\
  .reset_index(1,drop=True)\
  .apply(pd.Series)\
  .reset_index().rename(columns={0:'col1',1:'col3'})

Out[466]: 
  col1 col1 col3
0    a    b    d
1    a    b    e
2    a    c    d
3    a    c    e
4    f    g    i
5    f    g    j
6    f    h    i
7    f    h    j