Reads an NCL system colormap file or a user-defined colormap.
Available in version 6.1.0 and later.
function read_colormap_file ( filename : string )
The name of a colormap from NCL's system colormaps, or the name of a file containing a user-defined color map.
A float array of size n x 4 is returned, where n is the number of colors in the colormap. Colors are 4-tuples of red, green, blue, opacity values, in the range [0., 1.].
[Note: in NCL versions 6.1.2 or earlier, you must load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" to use this function. In later versions, you don't need to load anything.]
This is a convenience function for loading NCL's system colormaps or user-specified colormaps. While general-purpose in nature, its primary use-case is loading colormaps that are then assigned to resources such as cnFillPalette, cnFillColors, vcLevelPalette, vcLevelColors, stLevelColors, stLevelPalette, or mpFillColors.
Note that the function always returns 4-component colors, consisting of red/green/blue/opacity values. If the source color tables do not contain opacity values, a default of 1.0 (opaque) is returned.
The function follows all the naming and searching conventions for locating files as described here.
For several examples of manipulating color using the new color display introduced in NCL V6.1.0, see the "New color capabilities" examples page.
This example shows how to read an existing color map, and then subscript part of it for a filled contour plot:
cmap = read_colormap_file("BlAqGrYeOrReVi200") ... res@cnFillColors = cmap(3:,:) ; Skips the first two colorsExample 2
This example shows how to read an existing color map, and make part of it transparent for a filled contour plot:
cmap = read_colormap_file("OceanLakeLandSnow") ... cmap(0:1,) = 0.0 ; Make first two blue colors fully transparent res@cnFillColors = cmap