Select parts of a polygon GVector erase shared by another polygon GVector

The erase() function removes from the x "polygons" GVector parts that overlap with the y "polygons" GVector. You can also use the - operator (e.g., vect1 - vect2).

Usage

# S4 method for class 'GVector,GVector'
erase(x, y)

Arguments

x, y

GVectors.

Value

A GVector.

See also

c(), aggregate(), crop(), intersect(), union(), xor()

Examples

if (grassStarted()) {

# Setup
library(sf)

# Polygon of coastal Madagascar and Dypsis specimens
madCoast4 <- fastData("madCoast4") # polygons
madDypsis <- fastData("madDypsis") # points

# Convert vectors:
coast4 <- fast(madCoast4)
dypsis <- fast(madDypsis)

# Create another polygons vector from a convex hull around Dypsis points
hull <- convHull(dypsis)

### union()
###########

unioned <- union(coast4, hull)
plot(unioned)

plus <- coast4 + hull # same as union()

### intersect
#############

inter <- intersect(coast4, hull)
plot(coast4)
plot(hull, border = "red", add = TRUE)
plot(inter, border = "blue", add = TRUE)

### xor
#######

xr <- xor(coast4, hull)
plot(coast4)
plot(xr, border = "blue", add = TRUE)

### erase
#########

erased <- erase(coast4, hull)
plot(coast4)
plot(erased, border = "blue", add = TRUE)

minus <- coast4 - hull # same as erase()

}