Usage
To see the layers that are available, run the
available_layers() function:
Most layers are accessible by a shortcut function by the same name as
the object. Then you can use the data as you would any sf
object. The first time you try to access a layer, you will be prompted
for permission to download that layer to your hard drive. Subsequently
that layer is available locally for easy future access. For example:
There are two British Columbia boundary map layers available in
bcmaps:
bc_bound()for fast plotting with suitable detail for most figures (source: (7.5M) Provinces and States - The Atlas of Canada Base Maps for BC)bc_bound_hres()for geospatial analyses requiring detailed lineworks of British Columbia (source: Province of British Columbia - Boundary Terrestrial)
Simple Features objects
By default, all layers are returned as sf spatial
objects:
library(bcmaps)
library(sf)
# Load and plot the boundaries of B.C.
bc <- bc_bound()
plot(st_geometry(bc))
## Next load the Regional Districts data, then extract and plot the Kootenays
rd <- regional_districts()
kootenays <- rd[rd$ADMIN_AREA_NAME == "Regional District of Central Kootenay", ]
plot(st_geometry(kootenays), col = "lightseagreen", add = TRUE)
Digital Elevation Model for British Columbia 1:250,000
The cded_raster and cded_stars functions
return the 1:250,000 digital elevation model for British Columbia
bounded by some area of interest. Here we are retrieving the area
bounded by the Logan Lake census subdivision:
library(raster)
aoi <- census_subdivision()[census_subdivision()$CENSUS_SUBDIVISION_NAME == "Logan Lake", ]
aoi_raster <- cded_raster(aoi)
plot(aoi_raster)
It’s a beautiful day in the neighbourhood
A handy layer for creating maps for display is the
bc_neighbours layer, accessible with the function by the
same name. This example also illustrates using the popular ggplot2 package to plot maps
in R using geom_sf and the bc_cities()
function available in bcmaps:
library(ggplot2)
ggplot() +
geom_sf(data = bc_neighbours(), mapping = aes(fill = name)) +
geom_sf(data = bc_cities()) +
coord_sf(datum = NA) +
scale_fill_viridis_d(name = "Jurisdiction") +
theme_minimal()
Biogeoclimatic Zones
As of version 0.15.0 the B.C. BEC (Biogeoclimatic Ecosystem
Classification) map is available via the bec() function,
and an accompanying function bec_colours() function to
colour it:
bec <- bec()
library(ggplot2)
bec_sub <- bec[bec$ZONE %in% c("BG", "PP"),]
ggplot() +
geom_sf(data = bec_sub,
aes(fill = ZONE, col = ZONE)) +
scale_fill_manual(values = bec_colors()) +
scale_colour_manual(values = bec_colours())
Updating layers
When you first call a layer function bcmaps will remind
you when that layer was last updated in your cache with a message. For a
number of reasons, it might be necessary to get a fresh layer in your
bcmaps cache. The easiest way to update is to use the
force argument:
Another option is to actively manage your cache by deleting the old layer and calling the function again:
Utility Functions
The package also contains a few handy utility functions:
transform_bc_albers()for transforming anysfobject to BC Albers projectionbc_area()to get the total area of British Columbia in various unitsbc_bbox()to get an extend/bounding box for British Columbia