Returns a function that maps the interval [0,1] to a set of colours.
Interpolation is performed in the CIELAB colour space. Similar to
colorRamp(space = 'Lab')
, but hundreds of
times faster, and provides results in "#RRGGBB"
(or
"#RRGGBBAA"
) character form instead of RGB colour matrices.
colour_ramp(colors, na.color = NA, alpha = TRUE)
Arguments
colors |
Colours to interpolate; must be a valid argument to
grDevices::col2rgb() . This can be a character vector of
"#RRGGBB" or "#RRGGBBAA" , colour names from
grDevices::colors() , or a positive integer that indexes into
grDevices::palette() . |
na.color |
The colour to map to NA values (for example,
"#606060" for dark grey, or "#00000000" for transparent) and
values outside of [0,1]. Can itself by NA , which will simply cause
an NA to be inserted into the output. |
alpha |
Whether to include alpha transparency channels in interpolation.
If TRUE then the alpha information is included in the interpolation.
The returned colours will be provided in "#RRGGBBAA" format when needed,
i.e., in cases where the colour is not fully opaque, so that the "AA"
part is not equal to "FF" . Fully opaque colours will be returned in
"#RRGGBB" format. If FALSE , the alpha information is discarded
before interpolation and colours are always returned as "#RRGGBB" . |
Value
A function that takes a numeric vector and returns a character vector
of the same length with RGB or RGBA hex colours.
See also
Examples