Greenland ice loss example: animated & interactive

using Tyler
using GLMakie
using Arrow
using DataFrames
using TileProviders
using Extents
using Colors
using Dates
using HTTP

url = "https://github.com/JuliaGeo/JuliaGeoData/blob/365a09596bfca59e0977c20c2c2f566c0b29dbaa/assets/data/iceloss_subset.arrow?raw=true";

# parameter for scaling figure size
scale = 1;

# load ice loss data [courtesy of Chad Greene @ JPL]
resp = HTTP.get(url);
df = DataFrame(Arrow.Table(resp.body));

# select map provider
provider = TileProviders.Esri(:WorldImagery);

# Greenland extent
extent = Extent(X = (-54., -48.), Y = (68.8, 72.5));

# extract data
cnt = [length(foo) for foo in df.X];
X =  reduce(vcat,df.X);
Y =  reduce(vcat,df.Y);
Z = [repeat([i],c) for (i, c) = enumerate(cnt)];
Z = reduce(vcat,Z);

# make color map
nc = length(Makie.to_colormap(:thermal));
n = nrow(df);
alpha = zeros(nc);
alpha[1:maximum([1,round(Int64,1*nc/n)])] = alpha[1:maximum([1,round(Int64,1*nc/n)])] .* (1.05^-1.5);
alpha[maximum([1,round(Int64,1*nc/n)])] = 1;
cmap = Colors.alphacolor.(Makie.to_colormap(:thermal), alpha);
cmap = Observable(cmap);

# show map
m = Tyler.Map(extent; provider, figure=Figure(resolution=(1912 * scale, 2284 * scale)));

# create initial scatter plot
scatter!(m.axis, X, Y; color = Z, colormap = cmap, colorrange = [0, n], markersize = 10);

# add color bar
a,b = extrema(df.Date);
a = year(a);
b = year(b);
Colorbar(m.figure[1,2]; colormap = cmap, colorrange = [a,b], ticklabelsize = 50 * scale, width = 100 * scale);

# hide ticks, grid and lables
hidedecorations!(m.axis);

# hide frames
hidespines!(m.axis);

# wait for tiles to fully load
wait(m)

# ------ uncomment to create interactive-animated figure -----
# The Documenter does not allow creations of interactive plots

# loop to create animation

if interactive for k = 1:15 # reset apha alpha[:] = zeros(nc); cmap[] = Colors.alphacolor.(cmap[], alpha)

    for i in 2:1:n
        # modify alpha
        alpha[1:maximum([1,round(Int64,i*nc/n)])] = alpha[1:maximum([1,round(Int64,i*nc/n)])] .* (1.05^-1.5);
        alpha[maximum([1,round(Int64,i*nc/n)])] = 1;
        cmap[] = Colors.alphacolor.(cmap[], alpha);
        sleep(0.001);
    end
end

end

# -----------------------------------------------------------

Info

Ice loss from the Greenland Ice Sheet: 1972-2022.

Contact person: Alex Gardner & Chad Greene

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