Re: [R] plotmath question
On Fri, 18 Mar 2005, Berton Gunter wrote: 2) The plotmath Help state that expressions can be used for axis labels, so I would have expected the above to work without the eval()call -- but it does not. Would someone kindly explain to me why not -- i.e., what I have misunderstood. That is, to be clear, why does the following not work: Because substitute() doesn't evaluate its argument: the result is not an expression but a call to the expression() function. An example where it is clearer what is going on substitute(log(x),list(x=1)) doesn't return a number, even though log() returns a number. It returns a call to log() that still has to be evaluated -thomas for(i in seq(-3,to=3)) axis(1,at=i, lab=switch(sign(i)+2, substitute(expression(mu-j*sigma),list(j=i)), expression(mu), substitute(expression(mu+j*sigma),list(j=i __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] plotmath question
On Friday 18 March 2005 15:41, Berton Gunter wrote:
> R listers:
>
> I have been foiled by plotmath!
>
> (in R 2.01,Windows 2000)
>
> The task: Plot a normal density and label the ticks as mu - 3 sigma, mu - 2
> sigma, , mu + 3 sigma, where the mu's and sigmas appear as Greek
> symbols, of course.
>
> The following code does this:
>
> x<-seq(-3,to=3,by=.01)
> y<-dnorm(x)
> plot(x,y,type='h',col='lightblue',axes=FALSE)
> lines(x,y,col='darkblue')
> axis(2)
> for(i in seq(-3,to=3))
> axis(1,at=i, lab=switch(sign(i)+2,
>eval(substitute(expression(mu-j*sigma),list(j=-i))),
>expression(mu),
>eval(substitute(expression(mu+j*sigma),list(j=i)
> box()
>
> However, I think the code in the for loop is ugly and probably means that
> I'm doing it wrong. In particular:
>
> 1) Is there a neat way to use one axis() call and a vector (of
> expressions?) for the lab=argument?
Yes, expression objects can be vectors. e.g.:
## use switch as above for better formatting
lab = do.call(expression,
lapply(-3:3, function(i) {
bquote(mu + .(i) * sigma)
} ))
axis(1, at = -3:3, lab = lab)
> 2) The plotmath Help state that expressions can be used for axis labels, so
> I would have expected the above to work without the eval()call -- but it
> does not. Would someone kindly explain to me why not -- i.e., what I have
> misunderstood. That is, to be clear, why does the following not work:
>
> for(i in seq(-3,to=3))
> axis(1,at=i, lab=switch(sign(i)+2,
>substitute(expression(mu-j*sigma),list(j=i)),
>expression(mu),
>substitute(expression(mu+j*sigma),list(j=i
> is.expression(substitute(expression(mu-j*sigma),list(j=1)))
[1] FALSE
> is.expression(eval(substitute(expression(mu-j*sigma),list(j=1
[1] TRUE
?substitute says
Value:
The 'mode' of the result is generally '"call"' ...
which evidently have to be evaluated.
Hth,
Deepayan
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Re: [R] plotmath question
Bert,
This works fine and and seems a little simpler:
x<-seq(-3,to=3,by=.01)
y<-dnorm(x)
plot(x,y,type='h',col='lightblue',axes=FALSE)
lines(x,y,col='darkblue')
axis(2)
ll <- expression(mu-3*sigma, mu-2*sigma, mu-sigma, mu, mu+sigma,
mu+2*sigma, mu+3*sigma)
axis(1, at=-3:3, lab=ll)
box()
Cheers,
Andy
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Andy Jaworski
518-1-01
Process Laboratory
3M Corporate Research Laboratory
-
E-mail: [EMAIL PROTECTED]
Tel: (651) 733-6092
Fax: (651) 736-3122
Berton Gunter
<[EMAIL PROTECTED]
ne.com>To
Sent by: "'R-help'"
[EMAIL PROTECTED]
at.math.ethz.chcc
Subject
03/18/2005 03:41 [R] plotmath question
PM
R listers:
I have been foiled by plotmath!
(in R 2.01,Windows 2000)
The task: Plot a normal density and label the ticks as mu - 3 sigma, mu - 2
sigma, , mu + 3 sigma, where the mu's and sigmas appear as Greek
symbols, of course.
The following code does this:
x<-seq(-3,to=3,by=.01)
y<-dnorm(x)
plot(x,y,type='h',col='lightblue',axes=FALSE)
lines(x,y,col='darkblue')
axis(2)
for(i in seq(-3,to=3))
axis(1,at=i, lab=switch(sign(i)+2,
eval(substitute(expression(mu-j*sigma),list(j=-i))),
expression(mu),
eval(substitute(expression(mu+j*sigma),list(j=i)
box()
However, I think the code in the for loop is ugly and probably means that
I'm doing it wrong. In particular:
1) Is there a neat way to use one axis() call and a vector (of
expressions?)
for the lab=argument?
2) The plotmath Help state that expressions can be used for axis labels, so
I would have expected the above to work without the eval()call -- but it
does not. Would someone kindly explain to me why not -- i.e., what I have
misunderstood. That is, to be clear, why does the following not work:
for(i in seq(-3,to=3))
axis(1,at=i, lab=switch(sign(i)+2,
substitute(expression(mu-j*sigma),list(j=i)),
expression(mu),
substitute(expression(mu+j*sigma),list(j=i
Any further ideas,insights, or pointers to reference materials would also
be
appreciated. Many thanks.
-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
"The business of the statistician is to catalyze the scientific learning
process." - George E. P. Box
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[R] plotmath question
R listers: I have been foiled by plotmath! (in R 2.01,Windows 2000) The task: Plot a normal density and label the ticks as mu - 3 sigma, mu - 2 sigma, , mu + 3 sigma, where the mu's and sigmas appear as Greek symbols, of course. The following code does this: x<-seq(-3,to=3,by=.01) y<-dnorm(x) plot(x,y,type='h',col='lightblue',axes=FALSE) lines(x,y,col='darkblue') axis(2) for(i in seq(-3,to=3)) axis(1,at=i, lab=switch(sign(i)+2, eval(substitute(expression(mu-j*sigma),list(j=-i))), expression(mu), eval(substitute(expression(mu+j*sigma),list(j=i) box() However, I think the code in the for loop is ugly and probably means that I'm doing it wrong. In particular: 1) Is there a neat way to use one axis() call and a vector (of expressions?) for the lab=argument? 2) The plotmath Help state that expressions can be used for axis labels, so I would have expected the above to work without the eval()call -- but it does not. Would someone kindly explain to me why not -- i.e., what I have misunderstood. That is, to be clear, why does the following not work: for(i in seq(-3,to=3)) axis(1,at=i, lab=switch(sign(i)+2, substitute(expression(mu-j*sigma),list(j=i)), expression(mu), substitute(expression(mu+j*sigma),list(j=i Any further ideas,insights, or pointers to reference materials would also be appreciated. Many thanks. -- Bert Gunter Genentech Non-Clinical Statistics South San Francisco, CA "The business of the statistician is to catalyze the scientific learning process." - George E. P. Box __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] plotmath question: y'
"Pascal A. Niklaus" <[EMAIL PROTECTED]> writes: > Hi all, > > I wonder how to correctly write the following expression (it's the > axis label in a plot command): > > ylab=expression(y' == y - bar(y) ) > > Somehow the single quote in y' is causing the problems, I guess > because it is interpreted as a quote... > Does it have to be escaped? But how? y*minute or y*"'" should do it. -- O__ Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] plotmath question: y'
Pascal A. Niklaus wrote: Hi all, I wonder how to correctly write the following expression (it's the axis label in a plot command): ylab=expression(y' == y - bar(y) ) expression(y * "'" == y - bar(y)) Uwe Ligges Somehow the single quote in y' is causing the problems, I guess because it is interpreted as a quote... Does it have to be escaped? But how? Thanks for your help Pascal __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
[R] plotmath question: y'
Hi all, I wonder how to correctly write the following expression (it's the axis label in a plot command): ylab=expression(y' == y - bar(y) ) Somehow the single quote in y' is causing the problems, I guess because it is interpreted as a quote... Does it have to be escaped? But how? Thanks for your help Pascal __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
