# Operations on Coordinates Functions for shifting, zooming and envolving rectangle of a set of coordinates. ```r coords2coords(coords, xlim, ylim, xlim.ori, ylim.ori) zoom.coords(x, ...) ## Default S3 method: zoom.coords(x, xzoom, yzoom, xlim.ori, ylim.ori, xoff=0, yoff=0, ...) ## S3 method for class 'geodata' zoom.coords(x, ...) rect.coords(coords, xzoom = 1, yzoom=xzoom, add.to.plot=TRUE, quiet = FALSE, ...) ``` ## Arguments - `coords, x`: two column matrix or data-frame with coordinates. - `xlim`: range of the new x-coordinates. - `ylim`: range of the new y-coordinates. - `xlim.ori`: optional. Range of the original x-coordinates, by default the range of the original x-coordinates. - `ylim.ori`: optional. Range of the original y-coordinates, by default the range of the original y-coordinates. - `xzoom`: scalar, expanding factor in the x-direction. - `yzoom`: scalar, expanding factor in the y-direction. - `xoff`: scalar, shift in the x-direction. - `yoff`: scalar, shift in the y-direction. - `add.to.plot`: logical, if `TRUE` the retangle is added to the current plot. - `quiet`: logical, none is returned. - ``: further arguments to be passed to `rect`. ## Returns - **coords2coords and zoom.coords**: return an object of the same type as given in the argument `coords` with the transformed coordinates. - **rect.coords**: returns a matrix with the 4 coordinates of the rectangle defined by the coordinates. ## Author(s) Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br , Peter J. Diggle p.diggle@lancaster.ac.uk . ## See Also `subarea`, `rect` ## Examples ```r foo <- matrix(c(4,6,6,4,2,2,4,4), nc=2) foo1 <- zoom.coords(foo, 2) foo1 foo2 <- coords2coords(foo, c(6,10), c(6,10)) foo2 plot(1:10, 1:10, type="n") polygon(foo) polygon(foo1, lty=2) polygon(foo2, lwd=2) arrows(foo[,1], foo[,2],foo1[,1],foo1[,2], lty=2) arrows(foo[,1], foo[,2],foo2[,1],foo2[,2]) legend("topleft", c("foo", "foo1 (zoom.coords)", "foo2 (coords2coords)"), lty=c(1,2,1), lwd=c(1,1,2)) ## "zooming" part of The Gambia map gb <- gambia.borders/1000 gd <- gambia[,1:2]/1000 plot(gb, ty="l", asp=1, xlab="W-E (kilometres)", ylab="N-S (kilometres)") points(gd, pch=19, cex=0.5) r1b <- gb[gb[,1] < 420,] rc1 <- rect.coords(r1b, lty=2) r1bn <- zoom.coords(r1b, 1.8, xoff=90, yoff=-90) rc2 <- rect.coords(r1bn, xz=1.05) segments(rc1[c(1,3),1],rc1[c(1,3),2],rc2[c(1,3),1],rc2[c(1,3),2], lty=3) lines(r1bn) r1d <- gd[gd[,1] < 420,] r1dn <- zoom.coords(r1d, 1.7, xlim.o=range(r1b[,1],na.rm=TRUE), ylim.o=range(r1b[,2], na.rm=TRUE), xoff=90, yoff=-90) points(r1dn, pch=19, cex=0.5) text(450,1340, "Western Region", cex=1.5) ```

coords2coords function