Two == expressions in bquote

Peter's way is better than mine.

Bert Gunter
Genentech Nonclinical Biostatistics
 
 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Peter Dalgaard
Sent: Monday, January 25, 2010 12:57 PM
To: Larry Hotchkiss
Cc: r-help at r-project.org
Subject: Re: [R] Two == expressions in bquote

Hi,

I want to put text on a plot containing something like: a = b^2 = <squared

numeric value of b> using bquote.

Example:

  mu = 5
  plot(1:10,1:10)
  text(2,8, bquote(delta == mu^2))            # This works
  text(2.5,8, bquote(phantom(0) == .(mu^2)))  # but is unpredictable

  text(2,8, bquote(delta == mu^2 == .(mu^2))) # This doesn't work

The last text function returns the error:

     Error: unexpected '==' in "  text(2,8, bquote(delta == mu^2 =="

The comparison operators are not associative (they once were, but people 
were getting surprises from 3 > 2 > 1 evaluating to TRUE > 1 evaluating 
to FALSE). A set of suitably placed braces should clear things up:

text(2,8,bquote(delta == {mu^2 == .(mu^2)}))

The first two text functions work in this example, using a default

graphics window on a 64-bit Windows machine, and either R 2.11.0 development
edition for 64-bit Windows or R 9.2.2 on the same machine ((x 86)).

I don't mind the two statements except that when trying to automate this

by using the base x coordinate + epsilon*max(x), for example --

  x <- 1:10
  epsilon=0.05
  text(2+esilon*max(x),8, bquote(phantom(0) == .(mu^2)))

for the x position on the 2nd text function, the position of the

additional text is not predictable.

Thanks,

Larry Hotchkiss

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O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

______________________________________________
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.