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lines with colored segments
3 messages · David Stevens, Duncan Murdoch, Jim Lemon
On 12-11-04 8:29 AM, David Stevens wrote:
Hello all I'm trying to create a plot similar to a plot.default(..., type='b') with points plotted connected by lines that leave small gaps between the end of the line and the point symbol, BUT, with each line segment's color controlled by a category. plot... draws the line color uniformly according to the first color in a color sequence, ignoring the remainder. I can use segments() to give the proper colors using the x,y data, but those segments don't have the small gaps around the symbols. Somewhere, somehow, plot... either only draws the shortened segments, or draws the full segment, blanks out the space around the the symbol then adds the symbol (or, maybe something more sophisticated). Obviously I'm not the first to want to do this. Has anyone addressed this?
You might be the first to want to do this. It's a fairly strange plot: you have a category determined by the pair x[i] and x[i+1]. I think the only way to do this would be to draw the segments in a loop. For example, x <- 1:10 y <- 1:10 plot(x, y) # draw the points, in black col <- rainbow(9) for (i in 1:9) # draw the segments in colour lines(x[i:(i+1)], y[i:(i+1)], type='c', col=col[i]) Duncan Murdoch
On 11/05/2012 12:29 AM, David Stevens wrote:
Hello all I'm trying to create a plot similar to a plot.default(..., type='b') with points plotted connected by lines that leave small gaps between the end of the line and the point symbol, BUT, with each line segment's color controlled by a category. plot... draws the line color uniformly according to the first color in a color sequence, ignoring the remainder. I can use segments() to give the proper colors using the x,y data, but those segments don't have the small gaps around the symbols. Somewhere, somehow, plot... either only draws the shortened segments, or draws the full segment, blanks out the space around the the symbol then adds the symbol (or, maybe something more sophisticated). Obviously I'm not the first to want to do this. Has anyone addressed this?
Hi David, Try this: library(plotrix) x<-c(0,cumsum(rnorm(99))) y<-c(0,cumsum(rnorm(99))) xydist<-sqrt(x*x+y*y) plot(x,y,main="Random walk plot",xlab="X",ylab="Y",type="n") color.scale.lines(x,y,col=2+(diff(xydist)>0)) boxed.labels(x,y,labels=1:100,border=FALSE,cex=0.5) This colors a random walk with green if the "step" advances away from the start and red if it regresses toward the start. Just pass your colors in the "col=" argument. Jim