characters, mathematical expressions and computed values

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of mee1d3hs
Sent: Saturday, November 24, 2012 5:21 AM
To: r-help at r-project.org
Subject: Re: [R] characters, mathematical expressions and computed values

I still can't get this to work, I am just trying to learn and this is
supposed to be a feature of R, the ability to combine math notation in
charts and exhibits

I did some more work to try to show what I am trying it to and what is not
working

 x <- rnorm(1000,mean=10,sd=2)

 par(mfcol=c(3,3))
 meanx <- round(mean(x),digits=2)

  x <- rnorm(1000,mean=10,sd=2)

 par(mfcol=c(4,2))
 meanx <- round(mean(x),digits=2)

 #chart 1:
 hist(x,main=paste(" 1. Mean of X =",bquote(.(meanx))))
 #chart 2:
 hist(x,main=paste(" 2. Mean of X = ",substitute(meanx,list(meanx=meanx))))
 #chart 3:
 hist(x,main=expression("3. "*bar(x)*" = "))
 #chart 4:
 hist(x,main=expression(paste("4. ",bar(x)," = ",bquote(.(meanx)))))
 #chart 5:
 hist(x,main=expression(paste("5. ",bar(x)," =
",substitute(meanx,list(meanx=meanx)))))
 #chart 6:
 hist(x,main=bquote(paste("6. ",expression(bar(x))," = ",.(meanx))))
 #chart 7:
 hist(x,main=paste("7. ",expression(bar(x))," =
",substitute(meanx,list(meanx=meanx))))
#chart 8:
 hist(x,main=bquote("Heart Attack (" * bar(X)==.(meanx) *")"))



what i want to do is to show a title that says X Bar = mean, where Bar X is
the mathematical notation for the mean X with a bar on top and mean is the
mean value

the first 2 charts on top work using bquote() or substitute(), but they
write the word 'mean' instead of X bar. The third one shows the X Bar with
no value (it was a first attempt and I never included the value)

charts 4 and 5 and 6 attempt to incorporate either bquote() or substitute
into #3 to make it work, in both cases it seems the bquote or the substitute
is not properly being evaluated. In 6 and 7 specifically I put the
expression inside the bquote or paste to see if reversing would work,
finally 8 is the one suggested with slight modifications to replace round
and mean for the variable with that result. (the output I get is attached)

I am hoping that someone can help me understand what I am doing wrong, and I
guess how the nested functions are being evaluated. I am learning to use R,
and while I may really never need to use math notation (in fact in my work I
may confuse people more with X bar than using mean), I believe there is
value to learning how to use the functions, I can see how they would be
useful for writing code.functions that write code so one can dynamically
solve problems. I have done that in SAS and I may do it in R

I appreciate anyones help. Sorry for the long post, but I wanted to show my
process to solve and learn what is going on

Mario


sample.png <http://r.789695.n4.nabble.com/file/n4650645/sample.png>



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