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cex multiplier not exact

4 messages · Ali Tofigh, Uwe Ligges, Brian Ripley

Ali Tofigh
# 
Hi,

When I plot text and use cex to change the text size, I notice that the cex
multiplier is not exact. It looks as if the real size of text can take only
certain discrete values. Is there a workaround to get text to follow the cex
value more closely, or at least to be able to figure out what the real cex value
will be?

Here is an example that illustrates the problem:

cex <- seq(0.5, 1, 0.01)
x <- 0.05
y <- (1:length(cex))/length(cex)
labels <- paste("XXXXXX", cex)
plot.new()
text(x=x, y=y, labels=labels, pos=4, cex=cex)

/Ali
Uwe Ligges
#
On 23.10.2011 22:33, Ali Tofigh wrote:
Typically this is multiplied by the default pointsize of the current 
device and rounded to an integer - the resulting pointsize that you see 
with your code.

If you want to know it absolute precisely: This may even depend on the 
device and I think you will have to read the source code in order to 
find out how it is actually implemented for your current device (which 
you have not even stated).

Uwe Ligges
Brian Ripley
#
On Mon, 24 Oct 2011, Uwe Ligges wrote:

            

      
      
      
    

        
It may be in the help for that unstated device (the help for windows() 
says that it is rounded to bigpoints), and in some cases the rounding 
is in the OS services (it is for the X11() device, for example) and 
hence very hard to know precisely.

Oh, and the cex for text and for symbols (pch = 0:25) may not work the 
same way.

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Ali Tofigh
    

    

      
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On Mon, Oct 24, 2011 at 06:10, Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:

            

      
      
      
    

        
I was hoping to write code that would work on most devices. I'm trying
to write a function that plots and automatically adjusts the size of a
given text string to fit inside an predefined area (actually a
viewport from the grid package).

I try to do this by computing the width and height of the text using
the unit function: unit(1, "strwidth", x) and unit(1, "strheight, x").

            

      
      
      
    

        
information you and Uwe provided, I'm beginning to think that such a
function might not be feasible at all?

Thank you for all the info,
Best wishes
/Ali