pandas transform one row into multiple rows

Question

I have a dataframe as below.

My dataframe as below.

ID      list
1       a, b, c
2       a, s
3       NA
5       f, j, l

I need to break each items in the list column(String) into independent row as below:

ID      item
1       a
1       b
1       c
2       a
2       s
3       NA
5       f
5       j
5       l

Thanks.

use pandas explode with pandas str split. pandas.pydata.org/pandas-docs/stable/reference/api/… the split option converts your list column into a list, and the explode puts each item into it's own row — sammywemmy
– sammywemmy, Commented Feb 10, 2020 at 5:37

Henry Yik · Accepted Answer · 2020-02-10 05:43:41Z

4

Use str.split to separate your items then explode:

print (df.assign(list=df["list"].str.split(", ")).explode("list"))

   ID list
0   1    a
0   1    b
0   1    c
1   2    a
1   2    s
2   3  NaN
3   5    f
3   5    j
3   5    l

answered Feb 10, 2020 at 5:43

Henry Yik

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Comments

Pulkit Jha · Accepted Answer · 2020-02-10 06:14:01Z

0

A beginners approach : Just another way of doing the same thing using pd.DataFrame.stack

df['list'] = df['list'].map(lambda x : str(x).split(','))
dfOut = pd.DataFrame(df['list'].values.tolist())
dfOut.index = df['ID']
dfOut = dfOut.stack().reset_index()
del dfOut['level_1']
dfOut.rename(columns = {0 : 'list'}, inplace = True)

Output:

answered Feb 10, 2020 at 6:14

Pulkit Jha

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