R help - May 2013 - 'symbols' not drawing correctly in the 'y' dimension

Hello nice R people,

I'm struggling with the following code:

plot(c(0, 2), c(0, 2))
symbols(1, 1, circles=0.5, add=T, inches=F)
symbols(1, 1, squares=1, add=T, inches=F)
abline(v=c(0.5, 1.5), lty=2)
abline(h=c(0.5, 1.5), lty=2)

The a-b lines in the vertical direction coincide perfectly with the
borders of both the circle and the square drawn with 'symbols'.

However, the a-b lines in the horizontal direction, clearly show that
the circle is larger in the y-dimension than radius 0.5; same with the
square.

Using 'locator', shows the "y-radius" closer to 0.56

Any ideas what could be causing this? I have tried this in 3 different
machines,same result. Two are running Ubuntu with the R from the repo,
one is running Slackware with R version 2.15.3 compiled from source.

Any help much appreciated,
Damian

Hi,


On Thu, May 9, 2013 at 4:58 PM, Dami?n Cirelli <cirelli at ualberta.ca>
wrote:
> Hello nice R people,
>
> I'm struggling with the following code:
>
> plot(c(0, 2), c(0, 2))
> symbols(1, 1, circles=0.5, add=T, inches=F)
> symbols(1, 1, squares=1, add=T, inches=F)
> abline(v=c(0.5, 1.5), lty=2)
> abline(h=c(0.5, 1.5), lty=2)
>
> The a-b lines in the vertical direction coincide perfectly with the
> borders of both the circle and the square drawn with 'symbols'.
You need to specifically constrain the aspect ratio to be 1:1:

plot(c(0, 2), c(0, 2), asp=1)
symbols(1, 1, circles=0.5, add=T, inches=F)
symbols(1, 1, squares=1, add=T, inches=F)
abline(v=c(0.5, 1.5), lty=2)
abline(h=c(0.5, 1.5), lty=2)

If you read carefully ?symbols you'll see that by setting inches=FALSE
you've
specified that user coordinates be used to draw your symbols, but
those are not the same in x and y directions unless asp=1 - try
resizing the graphics window using your original code and mine, and
see what happens.

> However, the a-b lines in the horizontal direction, clearly show that
> the circle is larger in the y-dimension than radius 0.5; same with the
> square.
>
> Using 'locator', shows the "y-radius" closer to 0.56
>
> Any ideas what could be causing this? I have tried this in 3 different
> machines,same result. Two are running Ubuntu with the R from the repo,
> one is running Slackware with R version 2.15.3 compiled from source.
>
> Any help much appreciated,
> Damian
>
-- 
Sarah Goslee
http://www.functionaldiversity.org

Change the first line to

plot(c(0, 2), c(0, 2), asp=1)

That will set the aspect ratio between the vertical and horizontal axes to
be equal. 


-------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of Dami?n Cirelli
Sent: Thursday, May 9, 2013 3:58 PM
To: r-help at r-project.org
Subject: [R] 'symbols' not drawing correctly in the 'y'
dimension

Hello nice R people,

I'm struggling with the following code:

plot(c(0, 2), c(0, 2))
symbols(1, 1, circles=0.5, add=T, inches=F) symbols(1, 1, squares=1, add=T,
inches=F) abline(v=c(0.5, 1.5), lty=2) abline(h=c(0.5, 1.5), lty=2)

The a-b lines in the vertical direction coincide perfectly with the borders
of both the circle and the square drawn with 'symbols'.

However, the a-b lines in the horizontal direction, clearly show that the
circle is larger in the y-dimension than radius 0.5; same with the square.

Using 'locator', shows the "y-radius" closer to 0.56

Any ideas what could be causing this? I have tried this in 3 different
machines,same result. Two are running Ubuntu with the R from the repo, one
is running Slackware with R version 2.15.3 compiled from source.

Any help much appreciated,
Damian

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.