Pandas - Add Columns to a DataFrame Based in Dict from one of the Columns

Question

I have the pandas.DataFrame below:

One of the columns from the Dataframe, pontos, holds a dict for each of the rows.

What I want to do is add one column to the DataFrame for each key from this dict. So the new columns would be, in this example: rodada, mes, etc, and for each row, these columns would be populated with the respective value from the dict.

So far I've tried the following for one of the keys:

df_times["rodada"] = [df_times["pontos"].get('rodada') for d in df_times["pontos"]]

However, as a result I'm getting a new column rodada filled with None values:

Any hints on what I'm doing wrong?

Stephen Rauch · Accepted Answer · 2017-05-27 16:08:18Z

6

You can create a new dataframe and concat it to the current one like:

Code:

df2 = pd.concat([df, pd.DataFrame(list(df.pontos))], axis=1)

Test Code:

import pandas as pd

df = pd.DataFrame([
    ['A', dict(col1='1', col2='2')],
    ['B', dict(col1='3', col2='4')],
], columns=['X', 'D'])

print(df)

df2 = pd.concat([df, pd.DataFrame(list(df.D))], axis=1)
print(df2)

Results:

   X                           D
0  A  {'col2': '2', 'col1': '1'}
1  B  {'col2': '4', 'col1': '3'}

   X                           D col1 col2
0  A  {'col2': '2', 'col1': '1'}    1    2
1  B  {'col2': '4', 'col1': '3'}    3    4

answered May 27, 2017 at 16:08

Stephen Rauch♦

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Comments

paisanco · Accepted Answer · 2017-05-27 16:18:17Z

2

You just need a slight change in your comprehension to extract that data.

It should be:

df_times["rodada"] = [d.get('rodada') for d in df_times["pontos"]]

You want the values of the dictionary key 'rodada' to be the basis of your new column. So you iterate over those dictionary entries in the loop- in other words, d, and then extract the value by key to make the new column.

answered May 27, 2017 at 16:18

paisanco

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Comments

alexprice · Accepted Answer · 2019-05-05 12:23:38Z

0

you can also use join and pandas apply function:

df=df.join(df['pontos'].apply(pd.Series))

edited May 5, 2019 at 12:23

answered May 4, 2019 at 17:53

alexprice

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1 Comment

Nick Over a year ago

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