Super simple Python wrapper for LKH-3
Project description
PyLKH
This is a super simple Python wrapper for the constrained traveling salesman and vehicle routing problem solver called LKH-3.
If you want to use this wrapper, you should install LKH-3 first.
LKH-3 expects problems in the TSPLIB95 format. Using PyLKH you can solve problems represented as Python objects (via tsplib95) or files.
CAUTION: distances are represented by integer values in the TSPLIB format. This can produce unexpected behaviour for some problems, like those with all nodes within the unit square. The
precision
parameter controls this. More information here (pg. 6).
Install
pip install lkh
Example
import requests
import tsplib95
import lkh
problem_str = requests.get('http://vrp.atd-lab.inf.puc-rio.br/media/com_vrp/instances/A/A-n32-k5.vrp').text
problem = tsplib95.parse(problem_str)
solver_path = '../LKH-3.0.6/LKH'
lkh.solve(solver_path, problem=problem, max_trials=10000, runs=10)
Output:
[[26, 7, 13, 17, 19, 31, 21],
[24, 27],
[14, 28, 11, 4, 23, 3, 2, 6],
[29, 18, 8, 9, 22, 15, 10, 25, 5, 20],
[12, 1, 16, 30]]
API
lkh.solve(solver='LKH', problem=None, **kwargs)
Solve a problem.
Parameters
solver (str, optional): Path to LKH-3 executable.
problem (tsplib95.model.StandardProblem, optional): Problem object. problem
or problem_file
is required.
quiet (bool, optional): Suppress LKH-3 output.
kwargs (optional): Any LKH-3 parameter described here (pg. 5-7). Lowercase works. For example: runs=10
.
Returns
routes (list): List of lists of nodes.
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