Make invalid geometries valid

Function returns a valid geometry, not available before GEOS 3.8.0; from 3.10.0 two correction strategies

gMakeValid(spgeom, byid=FALSE, id = NULL, original=NULL, keepCollapsed=NULL)

Arguments

spgeom

sp object as defined in package sp

byid

Logical determining if the function should be applied across subgeometries (TRUE) or the entire object (FALSE)

id

Character vector defining id labels for the resulting geometries, if unspecified returned geometries will be labeled based on their parent geometries' labels.

original

default NULL; if GEOS < 3.10.0, TRUE, if GEOS >= 3.10.0, either set directly or taken from environment variable GEOS_MAKE_VALID with values LINEWORK for the original algorithm or STRUCTURE for the new algorithm. If GEOS_MAKE_VALID is STRUCTURE, original is FALSE

keepCollapsed

default NULL; If GEOS >= 3.10.0 and original is FALSE, the argument is used to control whether objects with dimension reduction are discarded (keepCollapsed is FALSE) or retained (TRUE). It may be set directly, or if NULL controlled by environment variable GEOS_MAKE_VALID_KEEPCOLLAPSED with values FALSE or TRUE. If GEOS_MAKE_VALID_KEEPCOLLAPSED is TRUE, keepCollapsed is TRUE

Details

Returns a valid geometry or collection of geometries of different types. For details on the buffered geometry fixer, see links from https://github.com/r-spatial/sf/issues/1655.

Author

Roger Bivand

See also

SpatialCollections-class

Examples

# Based on test geometries from sf
run <- FALSE
if (version_GEOS0() >= "3.8.0") run <- TRUE
if (run) {
X <- readWKT("POLYGON ((0 0, 0.5 0, 0.5 0.5, 0.5 0, 1 0, 1 1, 0 1, 0 0))")
gIsValid(X)
}
#> Warning: Ring Self-intersection at or near point 0.5 0
#> [1] FALSE
if (run) {
class(X)
}
#> [1] "SpatialPolygons"
#> attr(,"package")
#> [1] "sp"
if (run) {
row.names(X)
}
#> [1] "1"
if (run) {
Y <- gMakeValid(X)
}
if (run) {
gIsValid(Y)
}
#> [1] TRUE
if (run) {
class(Y)
}
#> [1] "SpatialCollections"
#> attr(,"package")
#> [1] "rgeos"
if (run) {
plot(slot(Y, "polyobj"))
plot(slot(Y, "lineobj"), add=TRUE, col="red")
}

if (run) {
row.names(slot(Y, "polyobj"))
}
#> [1] "1"
if (run) {
row.names(slot(Y, "lineobj"))
}
#> [1] "1"
run <- FALSE
if (version_GEOS0() >= "3.10.0") run <- TRUE
if (run) {
JTSplot <- function(x, fill="grey90", pts="black", main="", xlim, ylim) {
  if (inherits(x, "SpatialCollections")) {
    xl <- xp <- xpl <- NULL
    if (!is.null(slot(x, "lineobj"))) xl <- slot(x, "lineobj")
    if (!is.null(slot(x, "pointobj"))) xp <- slot(x, "pointobj")
    if (!is.null(slot(x, "polyobj"))) xpl <- slot(x, "polyobj")
    if (is.null(xl)) xl <- as(xpl, "SpatialLines")
    else xl <- rbind(xl, as(xpl, "SpatialLines"))
    if (is.null(xp)) xp <- as(xl, "SpatialPoints")
    else xp <- rbind(xp, as(xl, "SpatialPoints"))
  } else {
    xl <- as(x, "SpatialLines")
    xp <- as(xl, "SpatialPoints")
  }
  plot(coordinates(xp), type="n", main=main, xlab="", ylab="", axes=FALSE, xlim=xlim, ylim=ylim)
  plot(x, col=fill, border="transparent", add=TRUE, xlim=xlim, ylim=ylim)
  plot(xl, col=pts, add=TRUE, xlim=xlim, ylim=ylim)
  plot(xp, col=pts, add=TRUE, pch=14, xlim=xlim, ylim=ylim)
}
}
if (run) {
X <- readWKT(paste0("POLYGON ((10 70, 90 70, 90 50, 30 50, 30 30, ",
 "50 30, 50 90, 70 90, 70 10, 10 10, 10 70))", sep=""))
bb <- bbox(X)
opar <- par(mfrow=c(2,2))
JTSplot(X, fill="#dfdfff", pts="#00007c", main="input", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=TRUE), fill="#ffffa4", pts="#78b400",
 main="linework", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE), fill="#ffffa4", pts="#78b400",
 main="structure", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE, keepCollapsed=TRUE), fill="#ffffa4",
 pts="#78b400", main="structure + keep collapsed", xlim=bb[1,], ylim=bb[2,])
par(opar)
}

if (run) {
X <- readWKT(paste0("POLYGON ((10 70, 90 70, 90 10, 10 10, 10 70), ",
 "(60 80, 50 30, 0 20, 10 30, 60 80), (30 40, 60 30, 40 0, 30 40))", sep=""))
bb <- rbind(c(0, 90), c(0, 80))
opar <- par(mfrow=c(2,2))
JTSplot(X, fill="#dfdfff", pts="#00007c", main="input", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=TRUE), fill="#ffffa4", pts="#78b400",
 main="linework", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE), fill="#ffffa4", pts="#78b400",
 main="structure", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE, keepCollapsed=TRUE), fill="#ffffa4",
 pts="#78b400", main="structure + keep collapsed", xlim=bb[1,], ylim=bb[2,])
par(opar)
}

if (run) {
X <- readWKT(paste0("MULTIPOLYGON (((10 90, 60 90, 60 40, 10 40, 10 90)), ",
 "((40 60, 70 60, 70 30, 40 30, 40 60)), ((20 50, 50 50, 50 20, 20 20, 20 50)))", sep=""))
bb <- bbox(X)
opar <- par(mfrow=c(2,2))
JTSplot(X, fill="#dfdfff", pts="#00007c", main="input", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=TRUE), fill="#ffffa4", pts="#78b400",
 main="linework", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE), fill="#ffffa4", pts="#78b400",
 main="structure", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE, keepCollapsed=TRUE), fill="#ffffa4",
 pts="#78b400", main="structure + keep collapsed", xlim=bb[1,], ylim=bb[2,])
par(opar)
}

if (run) {
X <- readWKT(paste0("MULTIPOLYGON (((10 40, 40 40, 40 10, 10 10, 10 40), ", 
"(16 17, 31 32, 24 25, 16 17)), ((50 40, 50 40, 50 40, 50 40, 50 40)))", sep=""))
bb <- bbox(X)
opar <- par(mfrow=c(2,2))
JTSplot(X, fill="#dfdfff", pts="#00007c", main="input", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=TRUE), fill="#ffffa4", pts="#78b400",
 main="linework", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE), fill="#ffffa4", pts="#78b400",
 main="structure", xlim=bb[1,], ylim=bb[2,])
JTSplot(gMakeValid(X, original=FALSE, keepCollapsed=TRUE), fill="#ffffa4",
 pts="#78b400", main="structure + keep collapsed", xlim=bb[1,], ylim=bb[2,])
par(opar)
}

if (run) {
X <- readWKT(paste0("MULTIPOLYGON (((10 40, 40 40, 40 10, 10 10, 10 40), ", 
"(16 17, 31 32, 24 25, 16 17)), ((50 40, 50 40, 50 40, 50 40, 50 40)))", sep=""))
bb <- bbox(X)
opar <- par(mfrow=c(2,2))
JTSplot(X, fill="#dfdfff", pts="#00007c", main="input", xlim=bb[1,], ylim=bb[2,])
Sys.setenv("GEOS_MAKE_VALID"="LINEWORK")
JTSplot(gMakeValid(X), fill="#ffffa4", pts="#78b400", main="linework (env-var)",
 xlim=bb[1,], ylim=bb[2,])
Sys.setenv("GEOS_MAKE_VALID"="STRUCTURE")
Sys.setenv("GEOS_MAKE_VALID_KEEPCOLLAPSED"="FALSE")
JTSplot(gMakeValid(X), fill="#ffffa4", pts="#78b400", main="structure (env-vars)",
 xlim=bb[1,], ylim=bb[2,])
Sys.setenv("GEOS_MAKE_VALID_KEEPCOLLAPSED"="TRUE")
JTSplot(gMakeValid(X), fill="#ffffa4", pts="#78b400", main="structure + keep collapsed (env-vars)",
 xlim=bb[1,], ylim=bb[2,])
par(opar)
Sys.unsetenv("GEOS_MAKE_VALID")
Sys.unsetenv("GEOS_MAKE_VALID_KEEPCOLLAPSED")

}