Add one proportion column for every column

I have a dataframe with multiple columns and multiple rows, and my goal is to add, for every one of them, a new column right after it with it's proportion of the total sum of the column.

I have something like:

and I'm trying to transform it into something like:

a a.2 b b.2 c c.2
1 0.1 4 0.4 5 0.5 
8 0.8 2 0.2 3 0.3
1 0.1 4 0.4 2 0.2

But I can't figure out a way to NAME those new columns in add_column inside a loop.

So far, my code is as follows:

j=1
while (j <= length(colnames(eleicao))) {
  i <- colnames(sample)[j]
  nam <- paste("prop", i, sep = ".")
  j=j+1
  sample <- add_column(sample, parse(nam) = as.list(sample[i]/colSums(sample[i]))[[1]] .after = i)
}

I always get the same problem: Error: Column 'nam' already exists.

How can I accomplish my goal? How can I make add_column understand that I'm trying to name the column using the VALUE of 'nam'?

Solution

Following solution relies on dplyr included in the tidyverse.

library(tidyverse)

df <- tibble(
  a = c(1, 8, 1),
  b = c(4, 2, 4),
  c = c(5, 3, 2)
)

df %>% 
  mutate_all(funs(prop = . / sum(.)))

Which returns

# A tibble: 3 x 6
      a     b     c a_prop b_prop c_prop
  <dbl> <dbl> <dbl>  <dbl>  <dbl>  <dbl>
1     1     4     5    0.1    0.4    0.5
2     8     2     3    0.8    0.2    0.3
3     1     4     2    0.1    0.4    0.2