[R] adjusting color palette
B.Rowlingson at lancaster.ac.uk
Mon Jun 14 14:33:12 CEST 2004
Laura Quinn wrote:
> Is there a way to increase the "sensitivity" of the color palette in order
> to more clearly represent certain sections of data? For example I am
> wanting to clearly differentiate between height data for a rolling
> landscape but because of the extremes of the dataset (sea and mountain
> tops), the bulk of the landscape is shaded in closely approximating green
> - i have attempted to do this by using a larger color palette but this
> doesn't make things any clearer.
The colour is selected linearly by the value you are drawing. Hence
two solutions present themselves:
one, non-linearly scale your data. for your application I think
squaring x-mean(x) might stretch out the tails.
two, constructing a non-linearly varying palette. you can do this by
mucking about with the red, green, and blue values from the palette.
the functions 'col2rgb' and 'rgb' are useful.
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