Question

I am trying to make a simple illustration where a circle is plotted inside a square. I have used the rect() function from the grid package and the draw.circle() function from the plotrix package before so I thought this would be simple. But clearly I am missing something.

The following code seems to me like it should work:

require(plotrix)
require(grid)

plot(c(-1, 1), c(-1,1), type = "n")
rect( -.5, -.5, .5, .5) 
draw.circle( 0, 0, .5 )

however I end up with the circle lapping out of the square in the vertical dimension like this:

What in the heck am I missing?

If you have a simpler way of plotting circles and squares, I’d love to know about it. But I’d also like to know why my method above does not work.

Thanks!

Answer 1

You need to specify asp=1

require(plotrix)
require(grid)

plot(c(-1, 1), c(-1,1), type = "n", asp=1)
rect( -.5, -.5, .5, .5) 
draw.circle( 0, 0, .5 )

See also: Drawing non-intersecting circles
This one got me too!