Class ATSP – Asymmetric traveling salesperson problem

Constructor to create an instance of the asymmetric traveling salesperson problem (ATSP) and some auxiliary methods.

Usage

ATSP(x, labels = NULL, method = NULL)

as.ATSP(x)

# S3 method for class 'matrix'
as.ATSP(x)

# S3 method for class 'dist'
as.ATSP(x)

# S3 method for class 'ATSP'
print(x, ...)

# S3 method for class 'ATSP'
n_of_cities(x)

# S3 method for class 'ATSP'
labels(object, ...)

# S3 method for class 'ATSP'
image(x, order, col = gray.colors(64), ...)

# S3 method for class 'ATSP'
as.matrix(x, ...)

Arguments

x, object: an object (a square matrix) to be converted into an ATSP or, for the methods, an object of class ATSP.
labels: optional city labels. If not given, labels are taken from x.
method: optional name of the distance metric.
...: further arguments are passed on.
order: order of cities as an integer vector or an object of class TOUR.
col: color scheme for image.

Value

ATSP() returns x as an object of class ATSP.
n_of_cities() returns the number of cities in x.
labels() returns a vector with the names of the cities in x.

Details

Objects of class ATSP are internally represented by a matrix (use as.matrix() to get just the matrix).

ATSPs can be transformed into (larger) symmetric TSPs using reformulate_ATSP_as_TSP().

Author

Michael Hahsler

Examples

data <- matrix(runif(10^2), ncol = 10, dimnames = list(1:10, 1:10))

atsp <- ATSP(data)
atsp
#> object of class ‘ATSP’  (asymmetric TSP) 
#> 10 cities (distance ‘unknown’) 

## use some methods
n_of_cities(atsp)
#> [1] 10
labels(atsp)
#>  [1] "1"  "2"  "3"  "4"  "5"  "6"  "7"  "8"  "9"  "10"

## calculate a tour
tour <- solve_TSP(atsp, method = "nn")
tour
#> object of class ‘TOUR’ 
#> result of method ‘nn’ for 10 cities
#> tour length: 2.551933 

tour_length(tour)
#> [1] 2.551933

image(atsp, tour)