adjacencies: Adjacency, for use in creating area based meshes

In hypertidy/vaster: Tools for Raster Grid Logic

Adjacency, for use in creating area based meshes

Description

Functions 'bottom left', 'top left', 'bottom right', and 'top right' named by their initials, provide very low level relative positional structures for use in raster logic. These are used to traverse the divide left by area-based rasters which are inherently a discrete value across a finite element. If we want that element as part of a continuous surface we need to find local relative values for its corners. Used in quadmesh and anglr packages, and useful for calculating neighbourhood values.

Usage

bl(x)

tl(x)

br(x)

tr(x)

la(x)

ta(x)

ra(x)

ba(x)

image0(x, ...)

image1(x, ...)

text0(x, ...)

Arguments

x	matrix
...	arguments passed to image()

Details

bl, tl, br, and tr originally lived in affinity

Value

matrix, padded by one row and one column relative to input

Examples

(m <- matrix(1:12, 3))
tl(m)
tr(m)
bl(m)
br(m)
tl(br(m))
image0(tl(br(m)))
text0(tl(br(m)))

## this gives neighbours in adjacent positions
m <- matrix(1:12, ncol = 3, byrow = TRUE)

matrix(c(t(la(m)), t(ta(m)), t(ra(m)), t(ba(m))), ncol = 4)

## this gives neighbours in all 8 adjacent and diagonal positions
image(matrix(rowMeans(matrix(c(t(la(m)), t(ta(m)), t(ra(m)),
 t(ba(m)), t(bl(m)), t(tl(m)), t(br(m)), t(tr(m))),  ncol = 8), na.rm = TRUE),
 4, byrow = TRUE))

hypertidy/vaster documentation built on June 10, 2025, 8:09 a.m.