I want to append y to the 1st column of DF

Question

df = ({'a':[0,1,4],'b' : [10,2,5]})
y = [5,6]                

for i in y:
    x = df._append([{df.columns[0]: i}], ignore_index = True)
print(x)

Result is :

{'a':[0,1,4,6],
 'b' : [10,2,5]}

Result Should be:

{'a':[0,1,4,5,6],
 'b' : [10,2,5]}

Any help please?

score 2 · Answer 1 · answered Aug 03 '23 at 13:14

2

Use pd.concat:

pd.concat([df, pd.DataFrame({df.columns[0]:y})])

Output:

    A   B
0   0   10.0
1   1   2.0
2   4   5.0
0   5   NaN
1   6   NaN

answered Aug 03 '23 at 13:14

Guru Stron

score 1 · Answer 2 · answered Aug 03 '23 at 13:10

Why on earth would you use _append? This is an undocumented, private pandas method.

You should never append to a DataFrame iteratively.

The correct approach to perform this operation is concat:

x = pd.concat([df, pd.DataFrame({'A': y})])

Output:

2 Answers2