[英]Row-wise multiplication of selected columns with dplyr
What is the way to perform row-wise multiplication of all columns selected from a daraframe.对从 daraframe 中选择的所有列执行逐行乘法的方法是什么。 Below Mult columns is created explicitly by saying what variables to multiply.
下面的 Mult 列是通过说明要乘以哪些变量来显式创建的。
What if I selected different columns?如果我选择了不同的列怎么办? What code needs to be in mutate so it will multiply all columns selected before?
什么代码需要在 mutate 中才能乘以之前选择的所有列? NOTE: number of selected columns will not always be three.
注意:所选列的数量并不总是三。
example:例子:
library(tidyverse)
mtcars %>%
select(hp, qsec, disp) %>%
mutate(mult = hp * qsec * disp)
One possible way would be using rowProds
from package matrixStats
:一种可能的方式是使用
rowProds
从包matrixStats
:
mtcars %>%
select(hp, qsec, disp) %>%
mutate(mult=rowProds(as.matrix(.)))
But I am sure there is a more elegant way without using another package.但我相信有一种更优雅的方式而不使用其他包。
You can use Reduce
-您可以使用
Reduce
-
library(dplyr)
mtcars %>%
select(hp, qsec, disp) %>%
mutate(mult = Reduce(`*`, .))
Or rowwise
with prod
-或
rowwise
与prod
-
mtcars %>%
select(hp, qsec, disp) %>%
rowwise() %>%
mutate(mult = prod(c_across()))
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