set value to new column according to specific index

I want to create new column name 'pred_date' in df and set value according to specific index.

For example for index [1, 2, 3] I want to set value as the value in date column.

df:

    date   label    
1   1.1     1  
2   2.1     0
3   3.1     1 
4   4.1     1

new df:

    date   label    pred_date    
1   1.1     1       1.1 
2   2.1     0       2.1
3   3.1     1       3.1
4   4.1     1       Nan

>Solution :

You could use index.isin + where:

df['pred_date'] = df['date'].where(df.index.isin([1,2,3]))

Output:

   date  label  pred_date
1   1.1      1        1.1
2   2.1      0        2.1
3   3.1      1        3.1
4   4.1      1        NaN