python - How to convert column with list of values into rows in Pandas DataFrame

Question

Hi I have a dataframe like this:

    A             B 
0:  some value    [[L1, L2]]

I want to change it into:

    A             B 
0:  some value    L1
1:  some value    L2

How can I do that?

question from:https://stackoverflow.com/questions/39954668/how-to-convert-column-with-list-of-values-into-rows-in-pandas-dataframe

Answer 1

you can do it this way:

In [84]: df
Out[84]:
               A               B
0     some value      [[L1, L2]]
1  another value  [[L3, L4, L5]]

In [85]: (df['B'].apply(lambda x: pd.Series(x[0]))
   ....:         .stack()
   ....:         .reset_index(level=1, drop=True)
   ....:         .to_frame('B')
   ....:         .join(df[['A']], how='left')
   ....: )
Out[85]:
    B              A
0  L1     some value
0  L2     some value
1  L3  another value
1  L4  another value
1  L5  another value

UPDATE: a more generic solution