Re: [R] srt --- slope text with function?

From: Duncan Murdoch <>
Date: Sun 05 Feb 2006 - 08:19:59 EST

On 2/4/2006 3:50 PM, ivo welch wrote:
> [resent, plus small addition; I do not understand why gmail sent a
> weird charset.]
> Dear R wizards:
> I would love to write a general function that matches the slope of a plotted
> line in an xy-plot at a particular x,y location. something like
> x<- (1:10)^2; y<- 40:50;
> plot( x,y, type="l", xlim=c(0,90) )
> srt.at5 = x, y, 5);
> text( x[5],y[5], pos=3,;
> to do this, I first need to compute the function slope around x[5], which is
> an easy task. alas, the harder task is that I need to scale this by the
> plot aspect ratio and the axes. How can a function read this from the
> current plot?

I haven't done this, but you can presumably work it out from the conversions implied by the "fig", "fin", "plt", and/or "usr" values.
> (Has someone written such a function, perhaps more embellished, to save me
> the debugging effort?)
> Or, is there an alternative to srt, which slopes the text relative to the
> existing scale?
> *** come to think of it, what I would really like is the ability of
> text to 'snake' itself along the line itself. I doubt that this is
> easily possible, but I just wanted to ask.

Using strsplit and strwidth you should be able to do it, but it will probably look quite ugly.

Duncan Murdoch mailing list PLEASE do read the posting guide! Received on Sun Feb 05 08:27:35 2006

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