Re: [R] heatmap

From: Roger Bivand <Roger.Bivand_at_nhh.no>
Date: Tue 04 Oct 2005 - 18:58:52 EST


On Tue, 4 Oct 2005, Jim Lemon wrote:

> Andrea Zangrando wrote:
> > Hi,
> > i created a graph with heatmap(sma) function:
> >
> > heatmap(dataHeat(x))
> >
> > and I wish to change the gradation of colors from blue to red, how could
> > i do?
> > Using "heatmap(dataHeat(x), col=c(2,4))" i will use only 2 colors
> > without gradation.
> >
> The color.gradient function in the plotrix package returns a sequence of
> interpolated colors between any two starting colors or incomplete
> sequences of primaries.
>
> I noticed that a function named ramp (in the base package?) was
> mentioned, but I could not find it. If there is a function equivalent to
> color.gradient, I would like to know about it, as I try to avoid
> duplicating functions.

see ?colorRamp and look at:

> colorRampPalette

function (colors, ...)
{

    ramp <- colorRamp(colors, ...)
    function(n) {

        x <- ramp(seq(0, 1, length = n))
        rgb(x[, 1], x[, 2], x[, 3], max = 255)
    }
}

to see where it comes from. The colorRamp/colorRampPalette combination is quite remarkable and lots of fun ...

Roger

>
> Jim
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand@nhh.no

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Tue Oct 04 19:03:22 2005

This archive was generated by hypermail 2.1.8 : Sun 23 Oct 2005 - 18:16:47 EST