# st_relate: Compute DE9-IM relation between pairs of geometries, or match... In sf: Simple Features for R

## Description

Compute DE9-IM relation between pairs of geometries, or match it to a given pattern

## Usage

 `1` ```st_relate(x, y, pattern = NA_character_, sparse = !is.na(pattern)) ```

## Arguments

 `x` object of class `sf`, `sfc` or `sfg` `y` object of class `sf`, `sfc` or `sfg` `pattern` character; define the pattern to match to, see details. `sparse` logical; should a sparse matrix be returned (TRUE) or a dense matrix?

## Value

In case `pattern` is not given, `st_relate` returns a dense `character` matrix; element [i,j] has nine characters, referring to the DE9-IM relationship between x[i] and y[j], encoded as IxIy,IxBy,IxEy,BxIy,BxBy,BxEy,ExIy,ExBy,ExEy where I refers to interior, B to boundary, and E to exterior, and e.g. BxIy the dimensionality of the intersection of the the boundary of x[i] and the interior of y[j], which is one of 0,1,2,F, digits denoting dimensionality, F denoting not intersecting. When `pattern` is given, a dense logical matrix or sparse index list returned with matches to the given pattern; see st_intersection for a description of the returned matrix or list. See also https://en.wikipedia.org/wiki/DE-9IM for further explanation.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```p1 = st_point(c(0,0)) p2 = st_point(c(2,2)) pol1 = st_polygon(list(rbind(c(0,0),c(1,0),c(1,1),c(0,1),c(0,0)))) - 0.5 pol2 = pol1 + 1 pol3 = pol1 + 2 st_relate(st_sfc(p1, p2), st_sfc(pol1, pol2, pol3)) sfc = st_sfc(st_point(c(0,0)), st_point(c(3,3))) grd = st_make_grid(sfc, n = c(3,3)) st_intersects(grd) st_relate(grd, pattern = "****1****") # sides, not corners, internals st_relate(grd, pattern = "****0****") # only corners touch st_rook = function(a, b = a) st_relate(a, b, pattern = "F***1****") st_rook(grd) # queen neighbours, see \url{https://github.com/r-spatial/sf/issues/234#issuecomment-300511129} st_queen <- function(a, b = a) st_relate(a, b, pattern = "F***T****") ```

sf documentation built on July 24, 2019, 5:05 p.m.