How to change update cell value in Python Pandas dataframe

Question

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?

Answer 1

You can use the at() method to do this

df.at[0,’Age']= 20

Hope it helps!!

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Thanks!

Comments

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.

Was this the case for anyone else?

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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.

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Hey :) I was having the same issue, and using df.iat[] instead of df.at[] worked for me

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

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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!

Answer 2

Hi,

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

import pandas as pd
df1=pd.read_csv('my.csv')

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

I hope this will help you.

Answer 3

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