[R] [FORGED] Rotating points, preferably in grid

[Paul Murrell]

Hi

Do you mean something like this ... ?

library(grid)
grid.newpage()
pushViewport(viewport(xscale=c(-2,2), yscale=c(-2,2)))
grid.text('T', cos(theta), sin(theta), default.units="native",
           rot=(360/(2*pi))*(theta+(1/4)*2*pi))

Paul

On 25/08/16 14:16, Thomas Levine wrote:
> I want to make a plot in polar coordinates. I want to use pch with
> shapes that do not have radial symmetry, so I want to rotate them such
> that they face inwards. I am using grid for my plotting, but I provide
> motivating examples in graphics.
>
> The following plot almost gets me what I want.
>
>   theta <- 2*pi*seq(0,7/8,1/8)
>   plot(cos(theta), sin(theta), pch=2, axes=F, asp=1)
>
> But I want the points to face inwards. I can do something like this with
> text, but I can set only a constant rotation
>
>   plot.new()
>   plot.window(c(-1,1),c(-1,1), asp=1)
>   text(cos(theta), sin(theta), 'Tom', srt
>  =runif(1,0,360))
>
> To rotate all of the points, I can do something like this.
>
>   plot.new()
>   plot.window(c(-1,1),c(-1,1), asp=1)
>   for (the.theta in theta)
>     text(cos(the.theta), sin(the.theta), 'Tom',
>          srt=(360/(2*pi))*(the.theta-(1/4)*2*pi))
>
> So perhaps I could use a "T" instead of a numeric pch and consequently
> do something like this.
>
>   plot.new()
>   plot.window(c(-1,1),c(-1,1), asp=1)
>   for (the.theta in theta)
>     text(cos(the.theta), sin(the.theta), 'T',
>          srt=(360/(2*pi))*(the.theta+(1/4)*2*pi))
>
> But that seems a bit silly.
>
> Is there a more declarative way of doing this, preferably in grid?
>
> Thanks
>
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/