+1 vote

I have the following dataframe

```  Name Age
0 Mike 23
1 Eric 25
2 Donna 23
3 Will 23```

And I want to change the age of Mike. How can I do this?

Apr 8, 2019 in Python 146,324 views

+1 vote

You can use the at() method to do this

`df.at[0,’Age']= 20`

Hope it helps!!

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Thanks!

answered Apr 8, 2019 by Kunal
when using df.at[row_num, "Col B"] = "yes":

the at() method added a new column in my data frame instead of modifying the
Col B of my dataframe.

Hi @ken, Can you please share your data frame. The syntax of df.at() is correct but probably you aren't using it in accordance with your data frame.
Hey :) I was having the same issue, and using df.iat[] instead of df.at[] worked for me

"df.at[0,’Age']= 20" is not the correction solution

Hi, @There,

Even I have faced the same issue but the above-given solution has worked for me. Could you please share your workaround so that we can analyze why the solution isn't working!

Hi,

You can use at() method to update your dataset. I have attached one example for your reference.

```import pandas as pd
Place State
0 Kolkata WestBengal
1 Delhi Delhi
2 Bangalore Karnataka
3 Kolkata WestBengal
4 Delhi Delhi
```df1.at[0,'Place']= 'Mumbai'
```
Place State
0 Mumbai WestBengal
1 Delhi Delhi
2 Bangalore Karnataka
3 Kolkata WestBengal
4 Delhi Delhi

• 95,440 points

Use iloc:

```df.iloc[2,3] = 32

print(df)
#   A1  B1  C1  D1
#0   0   0   0   0
#1   0   0   0   0
#2   0   0   0  32
#3   0   0   0   0
```

Or if you want to modify by index and column name, use loc:

`df.loc[2, 'D1'] = 32`
answered Dec 9, 2020 by anonymous
• 82,880 points

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