A more complicated object
The raster package provides the RasterLayer
object, but also a couple of more complicated objects: RasterStack
and RasterBrick
. These two objects are designed for storing many rasters, all of the same extents and dimension (a.k.a. multi-band, or multi-layer rasters).
You can think of RasterLayer
like a matrix, but RasterStack
and RasterBrick
objects are more like three dimensional arrays. One additional thing you need to know to handle them is how to specify a particular layer.
You can use $
or [[
subsetting on a RasterStack
or RasterBrick
to grab one layer and return a new RasterLayer
object. For example, if x
is a RasterStack
, x$layer_name
or x[["layer_name"]]
will return a RasterLayer
with only the layer called layer_name
in it.
Let's look at a RasterStack
object called pop_by_age
that covers the same area as pop
but now contains layers for population broken into few different age groups.
Diese Übung ist Teil des Kurses
Visualizing Geospatial Data in R
Anleitung zur Übung
- Print
pop_by_age
. Can you see the names of all the layers? - Subset out the
under_1
layer using[[
subsetting. - Plot the
under_1
layer by passing your code from the previous instruction toplot()
.
Interaktive Übung
Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.
# Print pop_by_age
# Subset out the under_1 layer using [[
# Plot the under_1 layer