Create a pandas column from nested list

Question

How do i create a pandas column, where the lists inside my list become cells on their own? E.g.: I have the following nested list:

nested = [['1', '2', '3'],['2', '3', '1'],['3', '4'],['1']]

This list contains around 300 separate lists with strings of different length (min 1 max 5). Now i want to create a pandas dataframe column, where each of these lists in a single cell, not where each string is in a different cell. I tried it this way

df['new column'] = df[["col1", "col2"]].apply(lambda x: ''.join(x), axis=1)

but it gives me an error messsage, because there are some None values, because the lists initially had different lengths.

pd.DataFrame([nested]).T or more likely df['new_column'] = pd.Series(nested)? — AChampion
– AChampion, Commented Feb 13, 2019 at 21:27
The output should look like this: Dataframe with one column, each cell represents one list e.g. ['1', '2', '3',] is first cell, then ['2', '3', '1'] is second cell.. — Leo
– Leo, Commented Feb 13, 2019 at 21:33

Dani Mesejo · Accepted Answer · 2019-02-13 21:35:08Z

3

If I understood correctly this will be enough:

import pandas as pd

nested = [['1', '2', '3'], ['2', '3', '1'], ['3', '4'], ['1']]
df = pd.DataFrame({'col1': nested})
print(df)

Output

        col1
0  [1, 2, 3]
1  [2, 3, 1]
2     [3, 4]
3        [1]

answered Feb 13, 2019 at 21:35

Dani Mesejo

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