doGridMutation: Grid mutation
In jakobbossek/tspgen: Problem Generator for Traveling Salesperson Problems

Description Usage Arguments Value See Also

This mutation operator is designed to introduce a partial grid structure into to point of a given Euclidean problem instance. This is achieved by generating a random box of width and height w, h \in [box.min, box.max] and placing it at random within the boundaries [0, 1]^2. All points Q \subseteq P inside the box are affected by the mutation. Point set Q is replaced by a quadratic grid of points Q' with g = \lfloor √{|Q|} \rfloor rows and columns respectively. Note that if g^2 < |Q| we ignore |Q| - g random points of Q, i.e., these points are not touched. Subsequent, optional steps involve rotation and noise addition: with probability p.rot Q' is rotated by a random angle alpha \in [0, π/2] and with probability p.jitter all points in Q are perturbed by additive Gaussian noise with mean (0,0) and standard deviation jitter.sd in each dimension.

1 2	doGridMutation(coords, box.min = 0.1, box.max = 0.3, p.rot = 0, p.jitter = 0, jitter.sd = 0, ...)

`coords`	[`matrix`] An n times 2 matrix of point coordinates in [0, 1]^2.
`box.min`	[`numeric(1)`] Minimum for sampled box width and height respectively. Default is 0.1.
`box.max`	[`numeric(1)`] Maximum for sampled box width and height respectively. Default is 0.3.
`p.rot`	[`numeric(1)`] Probability of rotation, i.e, that mutated points are subject to rotation. Default is 0, i.e., no rotation.
`p.jitter`	[`numeric(1)`] Probability to add Gaussian noise to mutated points. Default is 0, i.e., no Gaussian noise at all.
`jitter.sd`	[`numeric(1)`] Standard deviation for Gaussian noise. Defaults to 0.1. Note that this parameter has an effect only if `p.jitter` is greater zero.
`...`	[any] Currently not used.