Flatten a list of elements in Pandas DataFrame

Question

My data-structure is:

ds = [{
    "name": "groupA",
    "subGroups": [123,456]
},
{
    "name": "groupB",
    "subGroups": ['aaa', 'bbb' , 'ccc']
}]

This gives the following dataframe

df = pd.DataFrame(ds)

    name    subGroups
0   groupA  [123, 456]
1   groupB  [aaa, bbb, ccc]   

I want:

    name    subGroupsFlattend
0   groupA  123
1   groupA  456
2   groupB  aaa
3   groupB  bbb
4   groupB  ccc

Any ideas?

Answer 1

Use explode:

df = df.explode('subGroups')

Answer 2

You can fix your output by following :

pd.DataFrame({'name':df.name.repeat(df.subGroups.str.len()),'subGroup':df.subGroups.sum()})
Out[364]: 
     name subGroup
0  groupA      123
0  groupA      456
1  groupB      aaa
1  groupB      bbb
1  groupB      ccc