Dear Henrique,
Thanks! This does work, and I find the following solution to my
original problem elegant enough:
> rep(list(character, integer, numeric, ...), c(3, 2, 2, ...))
Best regards,
Craig
Henrique Dallazuanna wrote:
From the help page of rep:
"Value:
An object of the same type as 'x' (except that 'rep' will coerce
pairlists to vector lists)."
So, you can do:
rep(list(character), 2)
On Tue, Jun 30, 2009 at 9:00 AM, Craig P. Pyrame <crap...@gmail.com
<mailto:crap...@gmail.com>> wrote:
Dear list,
I am trying to construct a list of functions using rep. I can't
understand the following:
> c(character, character) => list with two functions
> rep(character, 2) => error
The error says that "object of type 'special' is not subsettable",
and I have no idea what this means. Would you please help me.
The purpose of doing the above is that I need to use scan for
reading files that happen to be too large and a bit irregular for
read.table. To make scan work, I need to specify the types of
values in each column (record field). I can specify the 'what'
argument as follows:
> records <- scan(..., what = list(character(0), character(0),
integer(0), numeric(0), character(0), ...), ...)
but this quickly becomes boring for large enough records. (Why
does not scan take a character string with class names, as
read.table does, instead of a list with dummy objects?) So I am
trying to do tricks, and one idea that seems pretty simple is to
create a list of functions that create vectors of a particular
type, and apply them (using lapply) to get a list of prototype
objects:
> types = lapply(c(rep(character, 2), integer, numeric, ...),
function(type) type(0)) => error
But this fails, as above. Why? Why can c(character, character)
create a list of two functions, but rep(character, 2) can't?
Another solution to my problem I could find (and you'll hopefully
suggest an even better one) is to use class names instead, like so:
> types = lapply(c(rep('character', 2), 'integer', 'numeric',
...), function(type) vector(type, 0))
but I am still curious why the above doesn't work as I would
expect it to.
Best regards,
Craig
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--
Henrique Dallazuanna
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25° 25' 40" S 49° 16' 22" O
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