我有2個資料框：
df1
Name Apples Pears Grapes Peachs
James 3 5 5 2
Harry 1 0 2 9
Will 20 2 7 3
df2
Class User Factor
A Harry 3
A Will 2
A James 5
B NaN 4
我想在 df2 中創建一個名為的新列，Total它是 df1 中每個用戶的所有列的串列，乘以該用戶的因子 - 僅當它們在 A 類中時才應該這樣做。
這就是最終 df 的樣子
df2
Class User Factor Total
A Harry 3 [3,0,6,27]
A Will 2 [40,4,14,6]
A James 5 [15,25,25,10]
B NaN 4
這是我嘗試過的：
df2['Total'] = list(df1.Name.isin((df2.User) and (df2.Class==A)) * df2.Factor)
uj5u.com熱心網友回復：
這將滿足您的問題：
df2 = df2[df2.Class=='A'].join(df.set_index('Name'), on='User').set_index(['Class','User'])
df2['Total'] = df2.apply(lambda x: list(x * x.Factor)[1:], axis=1)
df2 = df2.reset_index()[['Class','User','Factor','Total']]
完整的測驗代碼：
import pandas as pd
import numpy as np
df = pd.DataFrame(columns=[
x.strip() for x in 'Name Apples Pears Grapes Peachs'.split()], data =[
['James', 3, 5, 5, 2],
['Harry', 1, 0, 2, 9],
['Will', 20, 2, 7, 3]])
print(df)
df2 = pd.DataFrame(columns=[
x.strip() for x in 'Class User Factor'.split()], data =[
['A', 'Harry', 3],
['A', 'Will', 2],
['A', 'James', 5],
['B', np.nan, 4]])
print(df2)
df2 = df2[df2.Class=='A'].join(df.set_index('Name'), on='User').set_index(['Class','User'])
df2['Total'] = df2.apply(lambda x: list(x * x.Factor)[1:], axis=1)
df2 = df2.reset_index()[['Class','User','Factor','Total']]
print(df2)
輸入：
Name Apples Pears Grapes Peachs
0 James 3 5 5 2
1 Harry 1 0 2 9
2 Will 20 2 7 3
Class User Factor
0 A Harry 3
1 A Will 2
2 A James 5
3 B NaN 4
輸出
Class User Factor Total
0 A Harry 3 [3, 0, 6, 27]
1 A Will 2 [40, 4, 14, 6]
2 A James 5 [15, 25, 25, 10]
uj5u.com熱心網友回復：
您可以使用：
# First lookup
factor = df2[df2['Class'] == 'A'].set_index('User')['Factor']
df1['Total'] = df1[cols].mul(df1['Name'].map(factor), axis=0).agg(list, axis=1)
# Second lookup
df2['Total'] = df2['User'].map(df1.set_index('Name')['Total'])
輸出：
>>> df2
Class User Factor Total
0 A Harry 3 [3, 0, 6, 27]
1 A Will 2 [40, 4, 14, 6]
2 A James 5 [15, 25, 25, 10]
3 B NaN 4 NaN
>>> df1
Name Apples Pears Grapes Peachs Total
0 James 3 5 5 2 [15, 25, 25, 10]
1 Harry 1 0 2 9 [3, 0, 6, 27]
2 Will 20 2 7 3 [40, 4, 14, 6]
uj5u.com熱心網友回復：
在線受虐狂，問候 ;)
df2['Total'] = pd.Series(df1.sort_values(by='Name').reset_index(drop=True).iloc[:,1:5]\
.mul(df2[df2.Class == 'A'].sort_values(by='User')['Factor'].reset_index(drop=True), axis=0)\
.values.tolist())
df2
輸出：
| 指數 | 班級 | 用戶 | 因素 | 全部的 |
|---|---|---|---|---|
| 0 | 一個 | 哈利 | 3 | 3,0,6,27 |
| 1 | 一個 | 將要 | 2 | 15,25,25,10 |
| 2 | 一個 | 詹姆士 | 5 | 40,4,14,6 |
| 3 | 乙 | 鈉 | 4 | 鈉 |
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