5. extra functionality

Source: vignettes/articles/mapview_05-extras.Rmd

mapview provides a couple of special convenience functions for all supported spatial data types:

  • viewExtent to view extents/bounding boxes of objects
  • syncing of multiple maps

There are also a few raster-only specialty functions:

  • viewRGB to view RGB (raster) images

For the following:

  • plainview to view raster images without map background
  • slideview to compare two raster/RGB images
  • cubeview to view 3D raster cubes

please refer to the individual help pages (e.g. ?cubeview)

All types

viewExtent

This can be handy to check whether features overlap or to just check where things are roughly located (e.g. in case we have big data sets, e.g. raster stacks).

library(mapview)
library(leaflet)
library(plainview)
library(leafsync)

viewExtent(poppendorf, color = "red") + viewExtent(breweries)

sync & latticeView

sync can be used to produce small multiples that are synchronised. Meaning that if we zoom into one panel, all other panels will also zoom. Additionally, the mouse position is also synced (indicated via a red circle). sync provides a very convenient way to compare multiple attributes of the same feature geometry set.

We can sync all panels:

m1 <- mapview(breweries, zcol = "village", map.types = "Esri.WorldImagery")
m2 <- mapview(breweries, zcol = "brewery", col.regions = heat.colors)
m3 <- mapview(breweries, zcol = "founded", legend = TRUE)
m4 <- leaflet() %>% addTiles() %>% addCircleMarkers(data = breweries)

sync(m1, m2, m3, m4)


Any combination of panels:

sync(list(m1, m2, m3, m4),
     sync = list(c(1, 4),
                 c(2, 3)))


We can also control the layout by specifying how many columns we want to have (rows will be automatically set):

sync(list(m1, m2, m3), ncol = 1)


latticeView will render small multiples without synchronising

latticeView(m1, m3)


Raster-only

viewRGB

viewRB can be used to view true- or false-color raster images. It expects a RasterStack or RasterBrick and the default setting will render layer combination 3-2-1

library(plainview)

viewRGB(poppendorf, r = 4, g = 3, b = 2)
## Warning in CPL_crs_from_input(x): GDAL Message 1: +init=epsg:XXXX syntax is
## deprecated. It might return a CRS with a non-EPSG compliant axis order.


viewRGB(poppendorf, 5, 4, 3)