[R] Gradients in bar charts XXXX

[Greg Snow]

Here is one approach:

tmp <- rbinom(10, 100, 0.78)

mp <- barplot(tmp, space=0, ylim=c(0,100))

tmpfun <- colorRamp( c('green','yellow',rep('red',8)) )

mat <- 1-row(matrix( nrow=100, ncol=10 ))/100
tmp2 <- tmpfun(mat)

mat2 <- as.raster( matrix( rgb(tmp2, maxColorValue=255), ncol=10) )

for(i in 1:10) mat2[ mat[,i] >= tmp[i]/100, i] <- NA


rasterImage(mat2, mp[1] - (mp[2]-mp[1])/2, 0, mp[10] + (mp[2]-mp[1])/2, 100,
	interpolate=FALSE)

barplot(tmp, col=NA, add=TRUE, space=0)


You can tweak it to your desire.  It might look a little better if
each bar were drawn independently with interpolate=TRUE (this would
also be needed if you had space between the bars).


On Mon, Apr 9, 2012 at 12:40 PM, Jason Rodriguez
<Jason.Rodriguez at dca.ga.gov> wrote:
> Hello, I have a graphics-related question:
>
> I was wondering if anyone knows of a way to create a bar chart that is colored with a three-part gradient that changes at fixed y-values. Each bar needs to fade green-to-yellow at Y=.10 and from yellow-to-red at Y=.20. Is there an option in a package somewhere that offers an easy way to do this?
>
> Attached is a chart I macgyvered together in Excel using a combination of a simple bar chart, fit line, and some drawing tools. I want to avoid doing it this way in the future by finding a way to replicate it in R.
>
> Any ideas?
>
> Thanks,
>
> Jason Michael Rodriguez
> Data Analyst
> State Housing Trust Fund for the Homeless
> Georgia Department of Community Affairs
> Email:  jason.rodriguez at dca.ga.gov
>
>
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-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com