Calculate percentages of a binary variable BY another variable in R

Question

I want to summarise the percentage of people that have been treated BY region.

I have created a dummy dataset for this purpose:

id <- seq(1:1000)
         


        

Answer 1

You could also use data.table:

library(data.table)

setDT(d)[,.(.N,prop=sum(treatment==2)/.N),
         by=region]
   region   N prop
1:      A 200  0.5
2:      B 200  0.5
3:      C 200  0.5
4:      D 200  0.5
5:      E 200  0.5