Re: [R] using color coded colorbars for bar plots

From: hadley wickham <h.wickham_at_gmail.com>
Date: Mon, 3 Dec 2007 10:30:19 -0600

On 12/2/07, Jim Lemon <jim_at_bitwrit.com.au> wrote:
> James.Dell@csiro.au wrote:
> > Hi Jim,
> > Thanks for getting back to me so quickly.
> >
> > I did look at color.legend, but that seems to plot colored blocks for
> > the observations (in this case the mean) and not for the color.scale
> > (which represents variance in this case). Unless there is a
> > functionality that I haven't discovered yet. If you have created a
> > similar plot and would be happy to share some code I'd be very
> > apprecitive.
> >
> Part of the problem is that you seem to have two names for the same
> variable in your code (Standard.Deviance and Standard.Deviation - unless
> that was a typo). Notice how I calculate the colors twice, the second
> time with a simple integer sequence to get the right number of evenly
> spaced colors. In your example, you calculated the colors for
> RankVar$Standard.Deviance again, but you don't need all those colors for
> the legend, and they're in the wrong order anyway. What is generally
> wanted for a color legend is the minimum and maximum values on the ends
> and a few linear interpolations in the middle.
>
> barplot(RankVar$MeanDecreaseAccuracy,
> col=color.scale(RankVar$Standard.Deviance,
> c(0,1,1),c(1,1,0),0),
> ylab = "Variable Importance",
> names.arg = rownames(RankVar),
> cex.names = .7,
> main = "Variables from RandomFishForest",
> sub= "Mean Decrease in Accuracy")
> col.labels<- c("Low","Mid","High")
> color.legend(6,13,11,14,col.labels,
> rect.col=color.scale(1:5,c(0,1,1),c(1,1,0),0))

Another option would be to use ggplot2:

install.packages("ggplot2")
library(ggplot2)

qplot(rownames(RankVar), MeanDecreaseAccuracy, data = RankVar, colour = Standard.Deviance)

and then use http://had.co.nz/ggplot2/scale_colour_gradient.html to control the choice of colours for the mapping.

Regards,

Hadley

-- 
http://had.co.nz/

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Received on Mon 03 Dec 2007 - 16:33:06 GMT

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