Given the below column:
col
0 NaN
1 Jan,Apr,Jul,Oct
2 Jan,Jun,Jul
3 Apr,May,Oct,Nov
4 NaN
...
How to convert the months abbreviation to month number (int)? and replace tghe comma with a hyphen? The output should look like:
col
0 NaN
1 01-04-07-10
2 01-06-07
3 04-05-10-11
4 NaN
...