How to assign a list to existing column of Pandas Data Frame?

Question

I apply some functions and generate a new column values to a existing column of Pandas dataframe. However df['col1'] = new_list does not work to assign new list to the column. Is it the wrong way and what is the accurate way to apply such operation ?

Answer 1

I think this question is looking for something like this.

new_list = [1,2,3]

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

And I think I found the answer here:

how to assign an entire list to each row of a pandas dataframe

Answer 2

It should work if length of the list is equal to the number of rows in the DataFrame

>>> df = pd.DataFrame({'A':[1,2,3], 'B':[4,5,6]})
>>> df['C'] = [10,20,30]
>>> df
   A  B   C
0  1  4  10
1  2  5  20
2  3  6  30

If your list is shorter or longer than DataFrame, then you'll receive an error Length of values does not match length of index.