Fast way to split column into multiple rows in Pandas

Question

I have the following data frame:

import pandas as pd
df = pd.DataFrame({ \'gene\':[\"foo\",
                            \"bar // lal\",
                                  


        

Answer 1

We can first split the column, expand it, stack it and then join it back to the original df like below:

df.drop('gene', axis=1).join(df['gene'].str.split('//', expand=True).stack().reset_index(level=1, drop=True).rename('gene'))

which gives us this:

    cell1   cell2   gene
0   5   12  foo
1   9   90  bar
1   9   90  lal
2   1   13  qux
3   7   87  woz