[Rd] symbols() draws squares too high (PR#9027)
Duncan Murdoch
murdoch at stats.uwo.ca
Fri Jun 23 16:07:17 CEST 2006
On 6/23/2006 9:55 AM, michellang at gmail.com wrote:
> Full_Name: Michel Lang
> Version: 2.2.1
> OS: 2.6.16-gentoo-r9 on x86_64
> Submission from: (NULL) (62.143.164.39)
>
>
> plot(-2:2, -2:2, type = "n")
> symbols(x = 0, y = 0, squares = 2, inches = FALSE, add = TRUE)
>
> This should plot a square with its center at (0,0) and side length 2, in other
> words a square from (-1,-1) as lower left angle to (1,1) as upper right angle.
>
> However, if you execute this line
> abline(h = c(-1,1))
> you see that the squares height is definitely too large.
This is not a bug.
The documentation says that when inches = FALSE, the units are those of
the x axis, so horizontal lines are not relevant. Try
abline(v=c(-1, 1))
If you want your x and y scales to be identical, I think you need to use
grid and lattice, rather than traditional graphics, and to set aspect="iso".
Duncan Murdoch
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