View source: R/unit.distances.R

somgrid | R Documentation |

Function `somgrid`

(modified from the version in the class package) sets up a grid of units, of a specified size
and topology. Distances between grid units are calculated by function `unit.distances`

.

somgrid( xdim = 8, ydim = 6, topo = c("rectangular", "hexagonal"), neighbourhood.fct = c("bubble", "gaussian"), toroidal = FALSE ) unit.distances(grid, toroidal)

`xdim` |
dimensions of the grid. |

`ydim` |
dimensions of the grid. |

`topo` |
choose between a hexagonal or rectangular topology. |

`neighbourhood.fct` |
choose between bubble and gaussian neighbourhoods when training a SOM. |

`toroidal` |
logical, whether the grid is toroidal or not. If not provided to the |

`grid` |
an object of class |

Function `somgrid`

returns an object of class "somgrid", with elements `pts`

, and the input arguments to the function.

Function `unit.distances`

returns a (symmetrical) matrix containing distances. When `grid$n.hood`

equals "circular", Euclidean distances are used; for `grid$n.hood`

is "square"
maximum distances. For toroidal maps (joined at the edges) distances are calculated for the shortest path.

mygrid <- somgrid(5, 5, "hexagonal") fakesom <- list(grid = mygrid) class(fakesom) <- "missSOM" oldpar <- par(mfrow = c(2,1)) dists <- unit.distances(mygrid) plot(fakesom, type="property", property = dists[1,], main="Distances to unit 1", zlim=c(0,6), palette = rainbow, ncolors = 7) dists <- unit.distances(mygrid, toroidal=TRUE) plot(fakesom, type="property", property = dists[1,], main="Distances to unit 1 (toroidal)", zlim=c(0,6), palette = rainbow, ncolors = 7) par(oldpar)

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