Integer, L, double, numeric

in R, integers can be setup using as.integer(x) or 1000L (L means L, long, because it used 32 bits representation of number which was longer than the old 8 or 16 bits !).

f <- integer(length) creates a vector of size length with only 0.

> f <- integer(1)
> f
[1] 0
> is.integer(f)
[1] TRUE
> identical(f, 0L)
[1] TRUE

The double() or numeric() are the same number representation:
real() for R <3.0.0 was the same but is deprecated.

microbenchmark(
  1L:2000L
  , 1:1000
  , as.integer(1):as.integer(2000)
  , times = 1000000L
)

Unit: nanoseconds
                           expr min  lq     mean median  uq      max
                       1L:2000L 129 144 181.2866    147 153    64915
                         1:1000 126 147 203.7078    149 154 20499610
 as.integer(1):as.integer(2000) 299 329 453.9530    335 350 32912817



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