TSPLIB {TSP}

R Documentation

Read and write TSPLIB files

Description

Reads and writes TSPLIB format files. TSPLIB files can be used by most TSP solvers. Sample instances for the TSP in TSPLIB format are available on the TSPLIB homepage (see references).

Usage

write_TSPLIB(x, file, precision = 6, inf = NULL, neg_inf = NULL)
read_TSPLIB(file, precision = 0)

Arguments

x	an object of class TSP or ATSP.
file	file name or a connection.
precision	controls the number of decimal places used to represent distances (see details). If x already is integer, this argument is ignored and x is used as is.
inf	replacement value for Inf (TSPLIB format cannot handle Inf). If inf is NULL, the default value of 2 times the maximum value in x (ignoring the infinity entries) is used.
neg_inf	replacement value for -Inf. If no value is specified, the default value of 2 times the smalles neg. number is used. If x only contains positive values, -1 is used.

Details

In the TSPLIB format distances are represented by integer values. Therefore, if x contains double values (which is normal in R) the values given in x are multiplied by 10^{precision} before coercion to integer. Note that therefore all results produced by programs using the TSPLIB file as input need to be divided by 10^{precision} (i.e., the decimal point has to be shifted precision placed to the left).

Currently only EDGE\_WEIGHT\_TYPE EXPLICIT is implemented!

Value

read_TSPLIB returns an object of class TSP or ATSP.

References

TSPLIB home page, http://www.iwr.uni-heidelberg.de/groups/comopt/software/TSPLIB95/

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