Dividing each cell in a data set by the column sum in R

Question

I am trying to divide each cell in a data frame by the sum of the column. For example, I have a data frame df:

sample   a   b   c
a2      1    4    6
a3             


        

Answer 1

You could do this in dplyr as well.

sample <- c("a2", "a3")
a <- c(1, 5)
b <- c(4, 5)
c <- c(6, 4)
dat <- data.frame(sample, a, b, c)
dat

library(dplyr)

dat %>%
    mutate(
        a.PCT = round(a/sum(a), 3),
        b.PCT = round(b/sum(b), 3),
        c.PCT = round(c/sum(c), 3))

  sample a b c a.PCT b.PCT c.PCT
1     a2 1 4 6 0.167 0.444   0.6
2     a3 5 5 4 0.833 0.556   0.4