get_layer_legend: Returns a legend for a raster layer
Description
Raster layers are accompanied with legends to identify what the colors mean.
This function retrieves those legend values and returns them as a data.frame
with the associated RGB color values. This will likely be most useful for
plotting and analysis of map layers.
Usage
get_layer_legend(url)
Value
A data.frame with two columns (color, values) and the number of
rows equal to the number of values in a layer