[R] Help with color.scale {plotrix}

[Kumar Mainali]

Hi Jim,

Thank you! Your color code does work. I still do not understand how red to
yellow in RGB space translates to cs1=c(1,1),cs2=(c(0,1),cs3=0. In other
words, I have RGB values for red and yellow. How do I go from there to the
code you sent?

Another question: some of my matrices have missing cells and I do not want
to assign any colors to the missing cells. The following code gives me
error. I am trying to use the output (cellcol) to the
function color2D.matplot.

> cellcol<-matrix("#000000", nrow=nrow(plotdata),ncol=ncol(plotdata))
> cellcol[x<0.33]<-color.scale(x[x<0.33],c(1,0.8),c(0,0.8),0, na.color=NA)
Error in cellcol[x < 0.33] <- color.scale(x[x < 0.33], c(1, 0.8), c(0,  :
  NAs are not allowed in subscripted assignments
In addition: Warning messages:
1: In min(x) : no non-missing arguments to min; returning Inf
2: In max(x) : no non-missing arguments to max; returning -Inf
ᐧ

Postdoctoral Associate
Department of Biology
University of Maryland, College Park

On Fri, Oct 9, 2015 at 7:24 AM, Jim Lemon <drjimlemon at gmail.com> wrote:

> Hi Kumar,
> The color.scale function translates numeric values into one or more
> intervals of color by a linear transformation into the numeric values that
> specify colors. One of three color spaces (rgb, hcl and hsv) can be
> specified, and the endpoints can be specified as "extremes=c(<minimum
> color>,<maximum color>" or as three vectors of numbers. By default, the RGB
> color space is used, so:
>
> # starts at RGB #FF0000 and finishes at RGB #FFFF00
> red to yellow - extremes=c("red","yellow") OR cs1=c(1,1),cs2=(c(0,1),cs3=0
> # starts at RGB #FFFF00 and finishes at RGB #00FF00
> yellow to green - extremes=c("yellow","green") OR
> cs1=c(1,0),cs2=(c(1,1),cs3=0
>
> Obviously the shades of colors that you want may differ from the above, so
> you have to play with the values to get the ones you want. In many cases,
> you will have to specify more than two numbers for the color specs to get
> the "in between" colors right, especially if the span of the colors is
> large.
>
> Jim
>
> On Fri, Oct 9, 2015 at 4:15 PM, Kumar Mainali <kpmainali at gmail.com> wrote:
>
>> Hi Jim and others:
>>
>> I needed color code for some color gradients in color.scale function. I
>> found that the following translates to green to yellow to
>> red: c(0,1,1),c(1,1,0),0. How does this string translate to the color
>> gradient? I would like to know the gradient code for red to yellow, yellow
>> to green and other ranges.
>>
>> Thanks,
>> Kumar Mainali
>>
>> Postdoctoral Associate
>> Department of Biology
>> University of Maryland, College Park
>>
>
>

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