[R] R internal data types

[Benjamin.STABLER@odot.state.or.us]

I am trying to figure out R data types and/or storage mode.  For example:

> #From a clean workspace
> gc()
         used (Mb) gc trigger (Mb)
Ncells 415227 11.1     597831   16
Vcells 103533  0.8     786432    6

> x <- seq(0,100000,1)
> is.integer(x)
[1] FALSE
> is.double(x)
[1] TRUE

> object.size(x)
[1] 800036

> gc()
         used (Mb) gc trigger (Mb)
Ncells 415247 11.1     667722 17.9
Vcells 203543  1.6     786432  6.0

> x <- as.integer(x)
> is.integer(x)
[1] TRUE
> is.double(x)
[1] FALSE

> gc()
         used (Mb) gc trigger (Mb)
Ncells 415249 11.1     741108 19.8
Vcells 153543  1.2     786432  6.0

> x <- 1:100000
> is.integer(x)

> gc()
         used (Mb) gc trigger (Mb)
Ncells 415278 11.1     741108 19.8
Vcells 153553  1.2     786432  6.0

> is.integer(3)
[1] FALSE
> is.double(3)
[1] TRUE

> is.integer(3 * as.integer(5))
[1] FALSE
> is.integer(as.integer(3) * as.integer(5))
[1] TRUE

> is.integer(c(as.integer(5),as.integer(6),as.integer(7)))
[1] TRUE
> is.integer(c(as.integer(5),as.integer(6),7))
[1] FALSE

> is.integer(seq(as.integer(5),as.integer(10),1))
[1] FALSE
> is.integer(seq(as.integer(5),as.integer(10),as.integer(1)))
[1] TRUE

So it looks like R stores numbers as doubles unless the are converted to
integers (long) with the as.integer() function or they are created with the
: operator.  If any of the numbers to a function are not type integer than
the function returns type double.  Is this the case?  Thanks.

Ben Stabler
Oregon Department of Transportation