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#######################################################################
# TSP - Traveling Salesperson Problem
# Copyrigth (C) 2011 Michael Hahsler and Kurt Hornik
#
# 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
# 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.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
## create a Euclidean TSP problem
ETSP <- function(x, labels = NULL) {
if(inherits(x, "ETSP")) return(x)
x <- as.ETSP(x)
if(!is.null(labels)) rownames(x) <- labels
x
}
## coercion
as.ETSP <- function(x) UseMethod("as.ETSP")
as.ETSP.matrix <- function(x){
mode(x) <- "numeric"
if(is.null(rownames(x))) rownames(x) <- 1:nrow(x)
class(x) <- c("ETSP", class(x))
x
}
as.ETSP.data.frame <- function(x){
as.ETSP(as.matrix(x))
}
as.TSP.ETSP <- function(x) TSP(dist(x))
as.matrix.ETSP <- function(x, ...) {
unclass(x)
}
## print
print.ETSP <- function(x, ...) {
cat("object of class", sQuote(class(x)[1]), "\n")
cat(n_of_cities(x), "cities", "(Euclidean TSP)\n")
}
## number of cities
n_of_cities.ETSP <- function(x) nrow(x)
## labels
labels.ETSP <- function(object, ...) rownames(object)
## image
image.ETSP <- function(x, order, col = gray.colors(64), ...) {
p <- n_of_cities(x)
if(missing(order)) order <- 1:p
x <- as.TSP(x)
graphics::image.default(1:p, 1:p, as.matrix(x)[order, order],
col = col, ...)
}
plot.ETSP <- function(x, y = NULL, tour = NULL, tour_lty = 2, tour_col = 1,...) {
x <- as.matrix(x)
plot(x, y = NULL, ...)
if(!is.null(y)) tour <- TOUR(y)
if(!is.null(tour)) polygon(x[tour,], lty = tour_lty, border = tour_col)
}
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