Rescale a SpatialPolygons object

Rescale a SpatialPolygons object

rescale_sp(
  sp,
  rotate_degrees = 0,
  scale = c(1, 1),
  shift = c(0, 0),
  center = NULL,
  share_center = FALSE,
  share_polygon_center = TRUE,
  update_bbox = TRUE,
  ...
)

Arguments

rotate_degrees

numeric value in degrees indicating rotation around the center, where positive values are clockwise rotation. This rotation is only applied to two columns in x defined by rotation_axes.

scale

numeric vector whose values are expanded to length ncol(x). After subtracting the center, the coordinates in each column are multiplied by the scale.

shift

numeric vector whose values are expanded to length ncol(x). The coordinates in each column are added to the shift, after applying scale and rotate_degrees

center

numeric vector whose values are expanded to length ncol(x), indicating the center point used for scale and rotate_degrees transformations. When center=NULL it is derived from the bounding box, which is the mean of the range for each column in x.

share_center

logical indicating whether all polygons should share the same center, where share_center=TRUE will adjust everything collectively, and share_center=FALSE will adjust each polygon independently relative to its own center coordinate.

...

additional arguments are ignored.

p

object sp::SpatialPolygons

Value

object sp::SpatialPolygons

Details

This function simply applies rescale_coordinates() to an object sp::SpatialPolygons, and it does so by calling rescale_ps on each sp::Polygons object contained in the sp input.

See also

Other venndir spatial: degrees_to_adj(), diff_degrees(), display_angles(), get_largest_polygon(), get_sp_buffer(), intersect_polygons(), mean_degree_arc(), mean_degrees(), nudge_sp(), rescale_coordinates(), sp_circles(), sp_ellipses(), spread_degrees(), union_polygons()

Examples

sp <- sp_ellipses(c(3, 2), c(2, 3),
   xradius=c(1, 4),
   yradius=c(5, 2))
sp1 <- intersect_polygons(sp);
sp2 <- rgeos::gDifference(sp[1], sp[2]);
sp3 <- rgeos::gDifference(sp[2], sp[1]);
sp123 <- sp::rbind.SpatialPolygons(sp1, sp2, sp3, makeUniqueIDs=TRUE);
sp123a <- rescale_sp(sp123,
   scale=c(1.5, 1.5),
   share_center=TRUE);
sp123b <- rescale_sp(sp123,
   scale=c(1.5, 1.5));
col3 <- c("#FF000077", "#FFDD0077", "#0000DD77");
par("mfrow"=c(2, 2));
plot(sp123, col=col3,
   main="original polygons",
   xlim=c(-10, 15), ylim=c(-5, 10));
axis(1, las=2); axis(2, las=2);
plot(sp123a, col=col3,
   main="share_center=TRUE",
   xlim=c(-10, 15), ylim=c(-5, 10));
axis(1, las=2); axis(2, las=2);
plot(sp123[1:2], col=col3[1:2],
   main="share_center=FALSE\nrescaling only the blue polygon",
   xlim=c(-10, 15), ylim=c(-5, 10));
axis(1, las=2); axis(2, las=2);
plot(sp123b[3], col=col3[3],
   add=TRUE);
plot(sp123[2:3], col=col3[2:3],
   main="share_center=FALSE\nrescaling only the red polygon",
   xlim=c(-10, 15), ylim=c(-5, 10));
axis(1, las=2); axis(2, las=2);
plot(sp123b[1], col=col3[1],
   add=TRUE);

par("mfrow"=c(1, 1));

{par("mfrow"=c(2, 2));
plot(sp123, col=col3,
   xlim=c(-4, 8), ylim=c(-4, 8))
title(main="Original polygons", line=0);
plot(rescale_sp(sp123, rotate_degrees=c(`11`=45, `12`=-10)), col=col3,
   xlim=c(-4, 8), ylim=c(-4, 8))
title(sub="yellow +45 degrees\nblue -10 degrees", line=0,
   main="share_polygon_center=TRUE (default)")
plot(rescale_sp(sp123, rotate_degrees=c(`11`=45, `12`=-10), share_polygon_center=FALSE), col=col3,
   xlim=c(-4, 8), ylim=c(-4, 8))
title(sub="yellow +45 degrees\nblue -10 degrees", line=0,
   main="share_polygon_center=FALSE\n(each polygon uses its center)")
plot(rescale_sp(sp123, rotate_degrees=c(`11`=45, `12`=-10), share_center=TRUE), col=col3,
   xlim=c(-4, 8), ylim=c(-4, 8))
title(sub="yellow +45 degrees\nblue -10 degrees", line=0,
   main="share_center=TRUE\n(all polygons share one global center)")
par("mfrow"=c(1, 1));}