Converting dataframe column values to list

Question

I have column which consits of values that are lists and some of them are not. I would like to get dataframe that only consists of rows(so drop non list rows) that have list values. Current DF column:

Column
["a", "b", "c"]
["a"]
a
b
["cc", "dd"]

Result:

Column
["a", "b", "c"]
["a"]
["cc", "dd"]

[row for row in df['Column'] if isinstance(row, list)] is going to be faster than using a pandas method — user3483203
– user3483203, Commented Sep 3, 2019 at 13:13

ComplicatedPhenomenon · Accepted Answer · 2019-09-03 13:15:50Z

2

import pandas as pd
df = pd.DataFrame({'Column': [["a", "b", "c"],["a"], 'a','b',["cc", "dd"]]})
print(df[df.Column.apply(lambda row: type(row)==list)])

Output

      Column
0  [a, b, c]
1        [a]
4   [cc, dd]

answered Sep 3, 2019 at 13:15

ComplicatedPhenomenon

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Comments

jezrael · Accepted Answer · 2019-09-03 13:18:22Z

1

Use isinstance method for test lists with map and filter by boolean indexing:

df1 = df[df['Column'].map(lambda x: isinstance(x, list))]

If need output only Column and possible multiple columns in real data:

df1 = df.loc[df['Column'].map(lambda x: isinstance(x, list)), ['Column']]

Or like in comment:

df1 = pd.DataFrame({'Column': [row for row in df['Column'] if isinstance(row, list)]})

edited Sep 3, 2019 at 13:18

answered Sep 3, 2019 at 13:13

jezrael

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