Cleaner way of constructing binary matrix from vector

Question

I have a fun challenge: I\'m trying to construct a a binary matrix from an integer vector. The binary matrix should contain as many rows as the length of vector, and as many

Answer 1

set.seed(1)
playv <- sample(0:5,20,replace=TRUE)
playv <- as.character(playv)
results <- model.matrix(~playv-1)

The columns in result you may rename.

I like the solution provided by Ananda Mahto and compared it to model.matrix. Here is a code

library(microbenchmark)

set.seed(1)
v <- sample(1:10,1e6,replace=TRUE)

f1 <- function(vec) {
  vec <- as.character(vec)
  model.matrix(~vec-1)
}

f2 <- function(vec) {
  table(sequence(length(vec)), vec)
}

microbenchmark(f1(v), f2(v), times=10)

model.matrix was a little bit faster then table

Unit: seconds
  expr      min       lq   median       uq      max neval
 f1(v) 2.890084 3.147535 3.296186 3.377536 3.667843    10
 f2(v) 4.824832 5.625541 5.757534 5.918329 5.966332    10