Fill empty fields in dataframe from a list of arrays

Question

I am currently working with a dataframe, which I am creating on the fly, basically what I have so far is as follows:

  In [2]: df
  Out[2]:
     A  B  C  D
  0  1  
  1  2  
  2  3

and I have an array of data arrays in numpy as follows:

array = [[1,2,3], [4,5,6], [7,8,9]]

I have tried to fill my dataframe with this data to get the following layout:

  In [2]: df
  Out[2]:
     A  B  C  D
  0  1  1  2  3
  1  2  4  5  6
  2  3  7  8  9

What I have been trying to do is the following:

new_df = df.append({k:v for k,v in zip(list_columns,array}, ignore_index=True)

But I don't get the results I need, I don't have that much experience with pandas, is there an efficient way to do it?

Thanks in advance!

score 2 · Accepted Answer · 2022-02-22 17:57:18Z

2

Try this:

df[['B', 'C', 'D']] = array

Output:

>>> df
   A  B  C  D
0  1  1  2  3
1  2  4  5  6
2  3  7  8  9

That will work whether the columns were already in the dateframe or not.

edited Feb 22, 2022 at 17:57

answered Feb 22, 2022 at 17:43

user17242583

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3 Comments

user17242583 Over a year ago

@isaac Did my solution work for you?

isaac.af95 Over a year ago

yes it works! Thanks a lot! but what about if I have the columns in a list names, there is other option than put them each one in the df columns names manually? @richardec

user17242583 Over a year ago

I think you can just do df[list_columns] = array in that case.

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