如何使用系列的相应值替换列数据（系列的索引）

Question

prices #This is a Pandas series
Apple 3
Banana 2
Pear 5

df.sales
Apple
Pear
Pear
Banana

我想将系列中的价格映射到df.sales，以便df.sales变为

3
5
5
2

Answer 1

您似乎需要map或replace：

#all non match values are replace to NaN
df['sales'] = df['sales'].map(s)

或者：

#all non match values are not changed
df['sales'] = df['sales'].replace(s)

#index values have to be unique
s = pd.Series([3,2,5],index=['Apple','Banana','Pear'])
df = pd.DataFrame({'sales':['Apple','Pear','Pear','Banana', 'Orange']})

df['sales1'] = df['sales'].map(s)
df['sales2'] = df['sales'].replace(s)
print (df)
    sales  sales1  sales2
0   Apple     3.0       3
1    Pear     5.0       5
2    Pear     5.0       5
3  Banana     2.0       2
4  Orange     NaN  Orange