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characters, mathematical expressions and computed values

5 messages · 1Rnwb, William Dunlap, S Ellison

1Rnwb
# 
Hello,

I have to add "Age (bar(x)=14.3) as a title on a chart. I am unable to get
this to working. I have tried bquote, substitute and expression, but they
are only doing a part of the job.

new<-
c(14.3, 18.5, 18.1, 17.7, 18, 15.9, 19.6, 17.3, 17.8, 17.5, 15.4, 
16.3, 15, 17.1, 17.1, 16.4, 15.2, 16.7, 16.7, 16.9, 14.5, 16.6, 
15.8, 15.2, 16.2, 15.6, 15, 17.1, 16.7, 15.6, 15, 15.8, 16.8, 
17, 15.2, 15.8, 15.7, 14.7, 17.3, 14.9, 16.8, 14.6, 19.3, 15.3, 
14.7, 13.3, 16.5, 16, 14.2, 16.1, 15.2, 13.4, 17.7, 15.5, 14.5, 
15.7, 13.6, 14.1, 20, 17.2, 16.5, 14.3, 13.7, 14.7, 15.4, 13.6, 
17, 17.3, 15.4, 15.5, 16.6, 15.8, 15.7, 14.7, 14.2, 14.2, 14, 
14.2, 19.1, 17.2, 18.3, 13.9, 16, 15.9, 14.9, 14.6, 15.9, 12.2, 
14.1, 12, 12.8, 17.1, 17, 15, 15.8, 15.9, 16.1, 18, 14.7, 18.9
)
hist(new, xlab='30-day Death Rate',xlim=c(7,22),main=expression("Heart
Attack(" * bar(X) * ")=" *
mean(new)))

I would appreciate any pointers on getting this correct.
Thanks



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William Dunlap
# 
I think that bquote, with its .() operator, suffices for [almost?] any single title;
don't bother fiddling with expression(), substitute(), or parse().   (You can make
those work in many situations, but if you stick with just bquote then you can
spend your time on the title itself.)

E.g.,
  hist(new, main=bquote("Heart Attack (" * bar(X)==.(mean(new)) * ")"))
or, if you want to limit the number of digits after the decimal point,
  hist(new, main=bquote("Heart Attack (" * bar(X)==.(round(mean(new),1)) * ")"))

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
S Ellison
# 
In this instance, using 
hist(new, main=bquote( "Heart Attack  " * (bar(X) ==.( mean(new) )) ) )

improves the parentheses slightly, as it uses plotmath parentheses instead of forcing text parentheses. 

Otherwise I agree completely; bquote is a neat way of doing the job.

S Ellison

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