I have a dataframe and I would like to maintain information. My data frame is like:
a <- c("a","b", "c", "d")
b <- c("e","f", "g", "h")
c <- c(1, 2, 1, 3) # multiply
d <- c("AB","BC", "CD", "DE")
e <- c(7, 5, 4, 3)
f<- c(2, 3, 5, 4)
g<- c(5, 7, 7, 9)
h <- c(6, 1, 2, 10)
m <- data.frame(a, b, d, e, f, g, h, c)
I would like to change e and f with the multiply of c * e ... c * h. How can I do it automatically without writing every single column?
With across:
library(dplyr)
mutate(m, across(c(e, f), ~ .x * c))
#mutate(m, across(c(e, f), `*`, c))
a b d e f c
1 a e AB 7 2 1
2 b f BC 10 6 2
3 c g CD 4 5 1
4 d h DE 9 12 3
or if you wanna keep the original columns:
mutate(m, across(c(e, f), ~ .x * c, .names = "new_{.col}"))
a b d e f c new_e new_f
1 a e AB 7 2 1 7 2
2 b f BC 10 6 2 20 12
3 c g CD 4 5 1 4 5
4 d h DE 9 12 3 27 36
or in base R
m[c(4,5)] <- sapply(m[c(4,5)], \(x) c*x)
# or even simpler (as pointed out by @zx8754 in the comments)
#m[, 4:5] <- m[, 4:5] * m$c
if you wanna keep the original columns:
m[paste0("new_", c("e", "f"))] <- sapply(m[c(4,5)], \(x) c*x)
#m[paste0("new_", c("e", "f"))] <- m[, 4:5] * m$c