R/diag.R

In caret: Classification and Regression Training

#  File src/library/stats/R/contrast.R
#  Part of the R package, http://www.R-project.org
#
#  Copyright (C) 1995-2012 The R Core Team
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  A copy of the GNU General Public License is available at
#  http://www.r-project.org/Licenses/

## a fast version of diag(n, .) / sparse-Diagonal() + dimnames
## Originally .Diag in stats:contrast.R

.RDiag <- function(nms, sparse) {
    ## no error checking here
    n <- as.integer(length(nms))
    d <- c(n,n)
    dn <- list(nms, nms)
    if(sparse) {
	if(is.null(tryCatch(loadNamespace("Matrix"), error = function(e)NULL)))
	    stop(gettextf("%s needs package 'Matrix' correctly installed",
                          "contr*(.., sparse=TRUE)"),
                 domain = NA)
	new("ddiMatrix", diag = "U", Dim = d, Dimnames = dn)
    } else
	array(c(rep.int(c(1, numeric(n)), n-1L), 1), d, dn)
}