More on coastlines

Following the great example from this example, I decided to compare the resolution for a thinner scale (Algarve area, South Portugal) of different coastlines available in R.

 
### import data
 
# from https://www.bodc.ac.uk/data/online_delivery/gebco/gebco_08_grid/ (requires login)
# load the GEBCO bathymetry+altitude. Don't forget to change your working directory.
pt.bathy = raster("gebco_08_-10_36_-6_42.nc")
# plot to check it is ok:
plot(pt.bathy)
 
 
### make the colour palette (copied from menugget blogg)
ocean.pal <- colorRampPalette( c("#000000", "#000413", "#000728", "#002650", "#005E8C", "#0096C8", "#45BCBB", "#8AE2AE", "#BCF8B9", "#DBFBDC"))
land.pal <- colorRampPalette( c("#467832", "#887438", "#B19D48", "#DBC758", "#FAE769", "#FAEB7E", "#FCED93", "#FCF1A7", "#FCF6C1", "#FDFAE0"))
 
## adapt the scale (copied from menugget blogg), more on our regional limits
zbreaks <- seq(-800, 500, by=20)  
cols <-c(ocean.pal(sum(zbreaks <= 0)-1), land.pal(sum(zbreaks>0)))
 
 
# Algarve detail limits: xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2)
 
# base map, with GEBCO bathymetry (small area)
plot(pt.bathy, xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2), asp=1,  col=cols, breaks=zbreaks, legend=FALSE)
# lines(coast, col=1, lwd=LWD)
# Add a layer with coastline from 'word' in red (package 'mapdata')
require(mapdata)
map("world", col="red", xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2), add=TRUE)
 
# Add a layer with coastline from 'wordHires' in violet (package 'mapdata')
map("worldHires", col="violet", xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2), add=TRUE)
 
# Add a layer with coastline from rworld in yellow (package rworld & rworldxtra
library(rworldmap)
require(rworldxtra)
plot(getMap(resolution='high'), border="yellow", add=TRUE)
 
# To add GADM borders package 'raster' in orange
# getData('ISO3') #use this to see your country iso name 

require(raster) 

pt.border = getData('GADM', country=c('PT'), level=0)
plot(pt.border, border="orange", add=T)
 

Created by Pretty R at inside-R.org






GADM coastal limits in orange are really nice to use in small areas. In this case, we can see the details in Ria Formosa coastal lagoon.

For altitude data we have a really nice solution, also within raster package:

# To add raster altitude data (for land area only, unfortunately):
pt.alt = getData('alt', country=c('PT'), mask=TRUE)
plot(pt.alt) #does not work because in the particular case o PT it is a list, so we need to extract only the first component.
plot(pt.alt[[1]])
plot(pt.border, border="grey80", add=T)

Created by Pretty R at inside-R.org

# If we want to see a small area (Algarve):
plot(pt.alt[[1]], xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2), asp=1)
plot(pt.border, border="grey60", add=T)
 
# For a highler resolution of Altitude:
alg.alt = getData('SRTM', lon=-8, lat=37)
plot(alg.alt, xlim=c(-8.2,-7.4), ylim=c(36.9, 37.2), asp=1, ylab=c("Latitude (N)"), xlab=c("Longitude (W)"))
plot(pt.border, border="grey60", add=T)

Created by Pretty R at inside-R.org

Now would be cool to select the best options and do it using ggplot2.