Module Vz.Colors

module Colors: sig .. end
Color schemes.

Colors provides functions to generate continuous and discrete color schemes to map quantitative or qualitative data to colors.

References.




Sequential color schemes

Sequential color schemes are for ordered scalar data.

val seq : ?a:float ->
?w:float ->
?s:float -> ?b:float -> ?c:float -> h:float -> unit -> float -> Gg.color
seq a w s b c h () is a function mapping the unit interval [0;1] to colors with a continuous sequential scheme where 0 is the darkest color and 1 the lightest. The parameters are:

Note. For equal b, c and w = 0, sequential schemes with different hues h have the same lightness. This can be used to generate multiple sequential schemes for multivariate data.

val seq_d : ?a:float ->
?w:float ->
?s:float -> ?b:float -> ?c:float -> h:float -> int -> Gg.color array
seq_d a w s b c h n is like Vz.Colors.seq except it returns a discrete sequential scheme with n colors and c defaults to min 0.88 (0.34 +. 0.06. * n).

Diverging color schemes

Diverging color schemes are for ordered scalar data with a defined midpoint (e.g. zero or the data average).

val div : ?a:float ->
?w:float ->
?s:float ->
?b:float ->
?c:float -> ?m:float -> h0:float -> h1:float -> unit -> float -> Gg.color
div a w s b c m h0 h1 () is a function mapping the unit interval [0;1] to colors for a continuous diverging scheme with 0 returning the darkest color of h0, and 1 the darkest color of h1.
val div_d : ?a:float ->
?w:float ->
?s:float ->
?b:float ->
?c:float -> ?m:float -> h0:float -> h1:float -> int -> Gg.color array
div_d a w s b c m h0 h1 n is like Vz.Colors.div except it returns a discrete diverging scheme with n colors and c defaults to min 0.88 (1.0 - 0.06 *. (11 - ((n / 2) + 1))).

Qualitative color schemes

Qualitative color schemes are used for qualitative (categorical, nominal) data.

type qual_fixed = [ `Brewer_accent_8
| `Brewer_dark2_8
| `Brewer_paired_12
| `Brewer_pastel1_9
| `Brewer_pastel2_8
| `Brewer_set1_9
| `Brewer_set2_8
| `Brewer_set3_12
| `Wijffelaars_17 ]

The type for qualitative color scheme with fixed colors. The suffix indicates the maximal number of colors in the scheme.
val qual_fixed_size : qual_fixed -> int
qual_fixed_size q is the maximal number of colors in qf.
val qual_fixed : ?a:float -> ?size:int -> qual_fixed -> Gg.color array
qual_fixed size q is fixed qualitative color scheme q with size colors (defaults to qual_fixed_size q) and alpha component a (defaults to 1).
Raises Invalid_argument if size is greater than qual_fixed_size b.
val qual_d : ?a:float ->
?eps:float ->
?r:float -> ?s:float -> ?b:float -> ?c:float -> int -> Gg.color array
qual_d eps r s b c n is a qualitative scheme with n colors. The parameters are: