Michael Hearne wrote:
> I'm trying to understand the usage of Colormaps,
> and LinearSegmentedColormaps in particular.
>
> I can create segmentdata that looks like the example at the bottom of
> this message. Each color has a 3x9 list of values.
>
> I can then construct a LinearSegmentedColormap as follows:
> palette = LinearSegmentedColormap('my_colormap',cdict)
>
> the 'N' attribute of my palette object reports that the length of the
> colormap is 256. However, when I try to retrieve the color tuple for
> any value above 50, I get black:
>
> palette(51) => (0.0, 0.0, 0.0, 1.0)
>
> Why aren't there 256 different colors in my colormap?
Because your color values state that for any normalized value between .2
and 1, the color should be RGB = (0.0,0.0,0.0). In your color
dictionary, the first number of each tuple/list specifies a value
between 0 and 1 to go with that color level. You probably instead want
to assign each color level to a level between 0 and 1. ie. For 5
levels, you want 0, .25, 0.5, 0.75, 1.0.
Ryan
> --Mike
>
> cdict = {'blue': [[0.0, 1.0, 1.0],
> [9.99999974738e-05, 0.749019622803, 0.749019622803],
> [0.0010000000475, 0.623529434204, 0.623529434204],
> [0.00200000009499, 0.498039215803, 0.498039215803],
> [0.00999999977648, 0.372549027205, 0.372549027205],
> [0.019999999553, 0.247058823705, 0.247058823705],
> [0.10000000149, 0.121568627656, 0.121568627656],
> [0.20000000298, 0.0, 0.0],
> [1.0, 0.0, 0.0]],
> 'green': [[0.0, 1.0, 1.0],
> [9.99999974738e-05, 0.749019622803, 0.749019622803],
> [0.0010000000475, 0.623529434204, 0.623529434204],
> [0.00200000009499, 0.498039215803, 0.498039215803],
> [0.00999999977648, 0.372549027205, 0.372549027205],
> [0.019999999553, 0.247058823705, 0.247058823705],
> [0.10000000149, 0.121568627656, 0.121568627656],
> [0.20000000298, 0.0, 0.0],
> [1.0, 0.0, 0.0]],
> 'red': [[0.0, 1.0, 1.0],
> [9.99999974738e-05, 0.749019622803, 0.749019622803],
> [0.0010000000475, 0.623529434204, 0.623529434204],
> [0.00200000009499, 0.498039215803, 0.498039215803],
> [0.00999999977648, 0.372549027205, 0.372549027205],
> [0.019999999553, 0.247058823705, 0.247058823705],
> [0.10000000149, 0.121568627656, 0.121568627656],
> [0.20000000298, 0.0, 0.0],
> [1.0, 0.0, 0.0]]}
>
>
>
>
>
> ------------------------------------------------------
> Michael Hearne
> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> (303) 273-8620
> USGS National Earthquake Information Center
> 1711 Illinois St. Golden CO 80401
> Senior Software Engineer
> Synergetics, Inc.
> ------------------------------------------------------
>
>
>
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--
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma
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