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I am trying to pass constant values in a python pandas data frame, and it is adding the only first row and the rest of the show as NaN. I am not sure what I am doing wrong. I tried all the possible answers but it still not working for. If you guys have any idea please let me know

weekdayDistance.loc[:,'UID'] = user.UID.head(1)
weekdayDistance['UID'] = user.UID.head(1)
weekdayDistance.loc['UID'] = user.UID.loc[0]

output:
a b c UID
1 1 1  1
2 2 2  NaN
3 3 3  NaN

what I want 
a b c UID
1 1 1  1
2 2 2  1
3 3 3  1
vinay karagod
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2 Answers2

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Simple answer would be

df['col_name'] = 1

or you can use insert, where 0 is the index of column, followed by column name and its constant value.

df.insert(0, colname, value)

This link here might give you explanation

Praveen Bushipaka
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You can do like below:

user['UID'] = 1

If just one row is getting filled, you can use ffill(). It will replicate the first row's value in all the rows.

user.UID = user.UID.ffill()
Mayank Porwal
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  • Did you try the exact statement that I gave? It should work fine. – Mayank Porwal Oct 18 '20 at 12:37
  • I am getting the value from other dataframe and passing the value to this dataframe and the above will work fine but I need the pass from other dataframe – vinay karagod Oct 18 '20 at 12:44
  • @vinaykaragod I have updated my answer. Run the `ffill()` statement after you get one row filled with constant value. This will work. Let me know if you face any issues. – Mayank Porwal Oct 18 '20 at 12:48