20201014_data_visualisation2.r

20201014_data_visualisation2.r

library(sp)
library(gstat)
library(raster)

graycol <- gray.colors(4, 0.55, 0.95)
# use IDW to generate zn.idw

data(meuse)
coordinates(meuse) <- c('x', 'y')
data(meuse.grid)
gridded(meuse.grid) <- c('x', 'y')
idw.out <- gstat::idw(zinc ~ 1, meuse, 
                      meuse.grid, idp = 2.5)
# idw.out.rast <- raster(idw.out)
# idw.out is an object of SpatialPixelsDataFrame
par(mar = c(1,1,1,1))
image(idw.out)
#      col = graycol, 
# breaks = log(c(100, 200, 400,
               800, 1800)))
data(meuse.riv)
meuse.lst <- list(Polygons(list(Polygon(meuse.riv)),
                           "meuse.riv"))
meuse.pol <- SpatialPolygons(meuse.lst)
plot(meuse.pol, add = TRUE)
plot(meuse, pch = 1, cex = sqrt(meuse$zinc)/20, add = TRUE)
legVals <- c(100, 200, 500, 1000, 2000)
legend(locator(1), legend = legVals, pch = 1, 
       pt.cex = sqrt(legVals)/20,
       bty = "n", title = "measured")
legend("topleft", legend = 
         c("100-200", "200-400", "400-800",
                                  "800-1800"), 
       fill = grays, bty = "n", title = "interpolated")