# [R] Rotating points, preferably in grid

Dalthorp, Daniel ddalthorp at usgs.gov
Thu Aug 25 04:52:44 CEST 2016

```Silly? Not really.

It's simple. It works.

You could jump into unicode for your text and make it look nicer, e.g.,
using '\u2191' or some other shape in place of 'T'

http://unicode.org/charts/
http://unicode.org/charts/PDF/U2190.pdf

-Dan

On Wed, Aug 24, 2016 at 7:16 PM, Thomas Levine <_ at thomaslevine.com> 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
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>

--
Dan Dalthorp, PhD
USGS Forest and Rangeland Ecosystem Science Center
Forest Sciences Lab, Rm 189
3200 SW Jefferson Way
Corvallis, OR 97331
ph: 541-750-0953
ddalthorp at usgs.gov

[[alternative HTML version deleted]]

```