adding value to only a single column in pandas dataframe

Question

I have a dataframe and i need to add data only to a specific column

DF

output :

I tried : df['A'].append(pd.DataFrame([valuetoadd]), ignore_index=True) where valuetoadd is a variable

What value do you want to add and to which column? Please share the expected output and sample input. — Mayank Porwal
– Mayank Porwal, Commented Nov 15, 2018 at 10:50

Mabel Villalba · Accepted Answer · 2018-11-15 18:07:02Z

12

You can use pandas.DataFrame.append with a dictionary (or list of dictionaries, one per row):

>> df.append({'A':32}, ignore_index=True)

    A    B    C
0   1    2    3
1   2    3    4
2   a    d    f
3  22    3    3
4  32  NaN  NaN


>> df.append([{'A':32}, {'C':34}], ignore_index=True)

     A    B    C
0    1    2    3
1    2    3    4
2    a    d    f
3   22    3    3
4   32  NaN  NaN
5  NaN  NaN   34

edited Nov 15, 2018 at 18:07

answered Nov 15, 2018 at 11:13

Mabel Villalba

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7 Comments

qwww Over a year ago

It is not adding

qwww Over a year ago

Instead of 32 I need value from a a variable to beadded

qwww Over a year ago

I am trying to add into empty dataframe

windsound Over a year ago

After checking both answers, I realized you will need to have df=df.append({'A':32}, ignore_index=True), so that you can have your df assigned the appended version.

Thomas Hilger Over a year ago

unfortunately it is deprecated now

|

Ansif_Muhammed · Accepted Answer · 2019-10-08 05:18:14Z

7

You can use pandas.DataFrame.append with a dictionary (or list of dictionaries, one per row):

df=df.append({'a':variable1}, ignore_index=True)
df=df.append({'a':variable1,'b':variable2}, ignore_index=True)

answered Oct 8, 2019 at 5:18

Ansif_Muhammed

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Comments

Thomas Hilger · Accepted Answer · 2023-10-27 13:04:50Z

1

As .append is deprecated now, another solution using pd.concat would be:

df = pd.concat([df, pd.DataFrame({"A":[32]})], ignore_index=True)

I'd prefer the old syntax, though.

answered Oct 27, 2023 at 13:04

Thomas Hilger

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