熊猫-将自身的行值乘以另一个值

Question

假设我有下表：

multiply   total   tax
Y          500     .1
Y          250     .5
N          300     .5

仅当乘法值为Y时，我才希望将总计设置为总计*税额

最终输出：

multiply   total   tax
Y          50      .1
Y          125     .5
N          300     .5

Answer 1

使用np.where

df['total'] = np.where(df['multiply'] == 'Y', df['total'] * df['tax'], df['total'])
print(df)

multiply  total  tax
       Y   50.0  0.1
       Y  125.0  0.5
       N  300.0  0.5

Answer 2

可以这样做

df.loc[df['multiply'] == 'Y', 'total'] = df.loc[df['multiply'] == 'Y', 'total'] * df.loc[df['multiply'] == 'Y', 'tax']

使用熊猫where和assign的另一种方法可能是：

df.where(df['multiply'] == 'N', df.assign(total = df['total'] * df['tax']))

输出：

    multiply    total   tax
0   Y           50      0.1
1   Y           125     0.5
2   N           300     0.5

Answer 3

我们在这里哥们

df.loc[df.multiply == 'Y', 'total'] = df.loc[df.multiply == 'Y', 'total'] * df.loc[df.multiply == 'Y', 'tax']

Answer 4

df=pd.DataFrame({'multiply':['Y','Y','N'],'total':[500,250,300],'tax':[.1,.5,.5]})
def myfunc(row):
    if(row[0]=='Y'):
        return float(row[1])*float(row[2])
    return row[2]
df['total']=df.apply(lambda x: myfunc(x),axis=1)
df

输出

multiply   tax  total
0   Y      0.1  50.0
1   Y      0.5  125.0
2   N      0.5  300.0