Pandas split column into multiple columns by comma

I am trying to split a column into multiple columns based on comma/space separation.

My dataframe currently looks like

     KEYS                                                  1
0   FIT-4270                                          4000.0439
1   FIT-4269                                          4000.0420, 4000.0471
2   FIT-4268                                          4000.0419
3   FIT-4266                                          4000.0499
4   FIT-4265                                          4000.0490, 4000.0499, 4000.0500, 4000.0504,

I would like

   KEYS                                                  1           2            3        4 
0   FIT-4270                                          4000.0439
1   FIT-4269                                          4000.0420  4000.0471
2   FIT-4268                                          4000.0419
3   FIT-4266                                          4000.0499
4   FIT-4265                                          4000.0490  4000.0499  4000.0500  4000.0504 

My code currently removes The KEYS column and I'm not sure why. Could anyone improve or help fix the issue?

v = dfcleancsv[1]

#splits the columns by spaces into new columns but removes KEYS?

dfcleancsv = dfcleancsv[1].str.split(' ').apply(Series, 1)

In case someone else wants to split a single column (deliminated by a value) into multiple columns - try this:

series.str.split(',', expand=True)

This answered the question I came here looking for.

Credit to EdChum's code that includes adding the split columns back to the dataframe.

pd.concat([df[[0]], df[1].str.split(', ', expand=True)], axis=1)

Note: The first argument df[[0]] is DataFrame.

The second argument df[1].str.split is the series that you want to split.

split Documentation

concat Documentation

Using Edchums answer of

pd.concat([df[[0]], df[1].str.split(', ', expand=True)], axis=1)

I was able to solve it by substituting my variables.

dfcleancsv = pd.concat([dfcleancsv['KEYS'], dfcleancsv[1].str.split(', ', expand=True)], axis=1)