在以下数据集中，我想乘以列 Size 中的值按列中的值 Month1 , Month2或 Month3取决于我们在列 Month 中的数字.所以如果在某行 Month值为 2，我想乘以列 Size 中的值按列 Month2 中的值并将结果保存在新列 NewSize 中.非常感谢您的帮助!
Orig = c("A","B","A","A","B","A","A","B","A")
Dest = c("B","A","C","B","A","C","B","A","C")
Month = c(1,1,1,2,2,2,3,3,3)
Size = c(30,20,10,10,20,20,30,50,20)
Month1 = c(1,0.2,0,1,0.2,0,1,0.2,0)
Month2 = c(0.6,1,0,0.6,1,0,0.6,1,0)
Month3 = c(0,1,0.6,0,1,0.6,0,1,0.6)
df <- data.frame(Orig,Dest,Month,Size,Month1,Month2,Month3)
df
Orig Dest Month Size Month1 Month2 Month3
1 A B 1 30 1.0 0.6 0.0
2 B A 1 20 0.2 1.0 1.0
3 A C 1 10 0.0 0.0 0.6
4 A B 2 10 1.0 0.6 0.0
5 B A 2 20 0.2 1.0 1.0
6 A C 2 20 0.0 0.0 0.6
7 A B 3 30 1.0 0.6 0.0
8 B A 3 50 0.2 1.0 1.0
9 A C 3 20 0.0 0.0 0.6
最佳答案
这是使用 ifelse 的另一种选择
> transform(df, NewSize=ifelse(Month==1, Size*Month1,
ifelse(Month==2, Size*Month2, Size*Month3)))
Orig Dest Month Size Month1 Month2 Month3 NewSize
1 A B 1 30 1.0 0.6 0.0 30
2 B A 1 20 0.2 1.0 1.0 4
3 A C 1 10 0.0 0.0 0.6 0
4 A B 2 10 1.0 0.6 0.0 6
5 B A 2 20 0.2 1.0 1.0 20
6 A C 2 20 0.0 0.0 0.6 0
7 A B 3 30 1.0 0.6 0.0 0
8 B A 3 50 0.2 1.0 1.0 50
9 A C 3 20 0.0 0.0 0.6 12
关于r - 根据特定列 R 中的值将列值乘以另一个值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29709248/