Faster %in% operator

Question

The fastmatch package implements a much faster version of match for repeated matches (e.g. in a loop):

set.seed(1)
library(fastmatch)
table <- 1L         


        

Answer 1

Look at the definition of %in%:

R> `%in%`
function (x, table) 
match(x, table, nomatch = 0L) > 0L

It's easy to write your own %fin% function:

`%fin%` <- function(x, table) {
  stopifnot(require(fastmatch))
  fmatch(x, table, nomatch = 0L) > 0L
}
system.time(for(i in 1:100) a <- x %in% table)
#    user  system elapsed 
#   1.780   0.000   1.782 
system.time(for(i in 1:100) b <- x %fin% table)
#    user  system elapsed 
#   0.052   0.000   0.054
identical(a, b)
# [1] TRUE