在python中对数据框中的列求和

Question

I am trying to add 3 columns' values to come up with a new column as total value. Code is below:

    df3[["Bronze","Gold","Silver"]] = 
    df3[["Bronze","Gold","Silver"]].astype("int")
    df3["Total Medal"]= df3.iloc[:, -3:0].sum(axis=1)
    df3[["Total Medal"]].astype("int")

I know that Bronze, Gold, Silver columns have 1 and 0 values and they are the last 3 columns in the dataframe. Their original types were "uint8" so I changed them to "int".

Total Medal column after these lines come out as type "float" (instead of int) and yield only the value 0. How can I properly add these columns?

Answer 1

要将 3 列的值添加到新列中，只需执行

    df['Total Medal'] = df.sum(axis=1)

Answer 2

This can eg be done using assign :

import numpy as np
import pandas as pd

#create data frame
data = {"gold":np.random.choice([0,1],size=10),"silver":np.random.choice([0,1],size=10), "bronze":np.random.choice([0,1],size=10)}
df = pd.DataFrame(data)

#calculate new column and add to dataframe
df = df.assign(mysum=df.gold+df.silver+df.bronze)

Edit: df["mysum"] = df.sum(axis=1) only works if your dataframe only has the three relevant columns, because it sums over all columns (and not only over the three you want).