:extrema fails if all values are equal

[SimonWoods]

If all array values are equal, using get with the :extrema option gives an error.

get(colorschemes[:sunset], fill(0.3,20,20), :extrema)

ERROR: InexactError: trunc(Int64, NaN)

It would be nice if this edge case was handled.

[cormullion]

Hi Simon (I remember your amazing contributions to the Mathematica Stack Exchange?)...

Looks like the problem is with remap here

so:

remap(x, 0.3, 0.3, 1, 10)
2-element Array{Float64,1}:
 NaN
 NaN

I suppose it could be fixed by inserting

iszero(first(rangescale) - last(rangescale)) && error("Empty rangescale: $(rangescale)")

at the start of that function, without too much of a penalty...

[SimonWoods]

Hi Cormullion, yes that's me. I haven't been active there for a while, most of my hobby programming is in Julia these days.

I'd argue for get to still return an image (albeit a boring one) when the array values are all equal. Maybe use the midpoint of the colour scheme?