The ReverseLookup command finds if a color is part of palette P and if so, returns its positive integer index in P.

If color is not a member of P and error will occur.

If fast is specified, the colors generated when P is expanded automatically will not be checked during the reverse lookup.

$P≔\mathrm{ColorTools}:-\mathrm{GetPalette}\left(''spring''\right)$

$P≔⟨Palette\; Spring:BlueRoseYellowGreenBlueGreenVioletCobaltYellowPurpleRedGreenBluePaleGreenOrangePurpleGreenSeaBluePaleYellowPaleBlueGreen⟩$

$\mathrm{ReverseLookup}\left(P\,P\left[1\right]\right)$

$''Blue''$

$\mathrm{Lookup}\left(P\,\mathrm{numcolors}\left(P\right)+1\right)$

$⟨RGB\; :\; 0\; 0\; 0⟩$

$\mathrm{ReverseLookup}\left(P\,\mathrm{Lookup}\left(P\,\mathrm{numcolors}\left(P\right)+1\right)\,\mathrm{fast}\right)$

Error, (in ColorTools:-Palette:-ReverseLookup) invalid color ColorTools:-Color("RGB",[0., 0., 0.]) is not in the palette

The ColorTools[Palette][ReverseLookup] command was introduced in Maple 16.

For more information on Maple 16 changes, see Updates in Maple 16.