[R] spacing of color key in filled.contour

[Clint Bowman]

I've gotten good results using the sine function to map colors. 
For example, when plotting x, map the range(x) to (-pi/2,pi/2) 
which the sine will transform to (-1,1), then add 1 and multiply by 
half the desired number of colors.  Now the integer values will 
pick the colors and give a pleasing display.

If the "squeeze" is taking place only over one of the tails (which 
sounds like your case) map the range from (0,pi/2) or (-pi/2,0) and 
make the necessary scaling adjustments to cover the number of 
colors desired.

Essentially, you are transforming the color mapping instead of 
transforming your data.

Clint

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On Thu, 20 Jan 2011, Jim Lemon wrote:

> On 01/20/2011 09:19 AM, claudia tebaldi wrote:
>>  Hi all
>> 
>>
>>  I'm plotting colored contour maps using filled.contour. My levels
>>  are very unevenly spaced, with, say, high resolution in the small
>>  numbers but ranges that can be an order of magnitude or two larger in
>>  absolute value compared to where the action takes place. Aside from
>>  transforming the data, is there a way to control the color spacing in
>>  the key to the right of the map? Right now I get most of the key
>>  length taken up by a couple of colors and the rest all squeezed into
>>  thin slices, which also creates a problem with the fourth axis labels
>>  getting drawn on top of one another.
>> 
> Hi Claudia,
> You can roll your own color key with the color.legend function in plotrix. 
> Just specify the colors you want in "rect.col" and the labels in "legend".
>
> Jim
>
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