[R] How to label and unlabel points on scatterplot with mouse pointer

[Greg Snow]

Here is one approach that works on Windows (but not other platforms):

HWidentify <- function(x,y,label=seq_along(x), xlab=deparse(substitute(x)),
				ylab=deparse(substitute(y)), ...) {

	plot(x,y,xlab=xlab, ylab=ylab,...)

	dx <- grconvertX(x,to='ndc')
	dy <- grconvertY(y,to='ndc')
	
	mm <- function(buttons, xx, yy) {
		d <- (xx-dx)^2 + (yy-dy)^2
		if ( all( d > .01 ) ){
			plot(x,y,xlab=xlab,ylab=ylab,...)
			return()
		}
		w <- which.min(d) 
		plot(x,y,xlab=xlab,ylab=ylab,...)
		points(x[w],y[w], cex=2, col='red')
		text(grconvertX(xx,from='ndc'),grconvertY(yy,from='ndc'), 
			label[w], col='green', adj=c(0,0))
		return()
	}

	md <- function(buttons, xx, yy) {
		if (any(buttons=='2')) return(1)
		return()
	}

	getGraphicsEvent('Right Click to exit', onMouseMove = mm, onMouseDown=md) 
	invisible()
}

tmpx <- runif(25)
tmpy <- rnorm(25)
HWidentify(tmpx,tmpy,LETTERS[1:25], pch=letters)

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Hitesh Singla
> Sent: Tuesday, August 11, 2009 10:50 PM
> To: r-help at r-project.org
> Subject: [R] How to label and unlabel points on scatterplot with mouse
> pointer
> 
> Dear all,
> 
> How can I label/unlabel points on scatterplot with mouse pointer. As
> the
> mouse approches near to point, it should label the closest point, then
> unlabel when it moves away.
> 
> How can I do in R? I be very thankful.
> 
> Thanks and Regards,
> 
> Hitesh Singla
> 
> --
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