I want to modify a specific data points in the pandas data frame under a condition. For example in the following table, I want to divide the data by 2 in column A where only row values of column B is greater than 1.
| Column A | Column B |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 2 |
| 6 | 2 |
| 7 | 1 |
| 8 | 1 |
Expected output :
| Column A | Column B |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 2 | 2 |
| 2.5 | 2 |
| 3 | 2 |
| 7 | 1 |
| 8 | 1 |
How can I modify the data frame with pandas?
CodePudding user response：
df.loc[df["Column B"] > 1,"Column A"] = df["Column A"]/2
Hope it Helps...
CodePudding user response：
you can try 'where' which takes the opposite condition and replaces it with the values.
import pandas as pd
data=pd.DataFrame(data={'A':[1,2,3,4,5,6,7,8],'B':[1,1,1,2,2,2,1,1]})
data.A=data.A.where(data.B<=1,data.A/2)
CodePudding user response：
try this:
df["A"]=df.apply(lambda x:x["A"]/2 if x["B"]>1 else x["A"],axis=1)