add netCDF example

docs/Project.toml

@@ -35,6 +35,7 @@ Literate = "98b081ad-f1c9-55d3-8b20-4c87d4299306"
 Makie = "ee78f7c6-11fb-53f2-987a-cfe4a2b5a57a"
 MakieCore = "20f20a25-4f0e-4fdf-b5d1-57303727442b"
 MakieThemes = "e296ed71-da82-5faf-88ab-0034a9761098"
+NCDatasets = "85f8d34a-cbdd-5861-8df4-14fed0d494ab"
 NaturalEarth = "436b0209-26ab-4e65-94a9-6526d86fea76"
 Polylabel = "49a44318-e865-4b63-9842-695152d634c1"
 ProgressMeter = "92933f4c-e287-5a05-a399-4b506db050ca"

docs/make.jl

@@ -52,6 +52,7 @@ examples = String[
     # "projections.jl",
     "tissot.jl",
     # "rotating_earth.jl",
+    "netcdf.jl"
 ]
 example_dir = joinpath(dirname(@__DIR__), "examples")
 mkpath(example_dir)

docs/src/examples.md

@@ -35,6 +35,7 @@ meshimage
 projections
 tissot
 healpix
+netcdf
 ```
 
 ## Examples from Cartopy

examples/netcdf.jl

@@ -0,0 +1,50 @@
+#=
+# Data from netCDF
+Here, we show how to plot data from a netCDF file via GeoMakie.
+The example uses global sea surface temperature.
+=#
+
+using NCDatasets
+using GeoMakie
+using CairoMakie
+
+# Download the data
+src = "https://www.unidata.ucar.edu/software/netcdf/examples/tos_O1_2001-2002.nc"
+dst = "tos_O1_2001-2002.nc"
+download(src, dst)
+
+# Read latitude and longitude coordinates + sea surface temperature
+# Temperature has a time index... just select the first time step
+ds = NCDataset("tos_O1_2001-2002.nc", "r")
+lat = ds["lat"][:]
+lon = ds["lon"][:]
+temp = ds["tos"][:,:,1]
+close(ds)
+rm("tos_O1_2001-2002.nc")
+
+# Longitude ranges from 0 to 360
+# Convert to -180 to 180 and sort temp accordingly
+lon[lon .> 180] .-= 360
+sort_idx = sortperm(lon)
+lon = lon[sort_idx]
+temp = temp[sort_idx,:]
+
+# Plot the data as a heatmap with coastlines and a colorbar.
+#
+# First, create a figure, and a GeoAxis inside it:
+fig = Figure(size=(900,500))
+ax = GeoAxis(fig[1,1]; dest="+proj=longlat +datum=WGS84", xgridwidth=0.15, ygridwidth=0.15)
+## then, plot a heatmap with the data we used!
+sp = heatmap!(ax, lon, lat, temp; colormap=cgrad(:viridis))
+## finally, plot some coastlines to give the plot context
+lines!(ax, GeoMakie.coastlines(); color = :black, linewidth=1.0)
+## and a colorbar
+cb = Colorbar(fig[1, 2], sp, width=30, height=Relative(0.7), label="Sea Surface Temperature (K)")
+fig
+
+#=
+```@cardmeta
+Cover = fig
+Description = "Plotting data from a netCDF file via NCDatasets.jl"
+```
+=#