R help - Nov 2007 - Using plotmath expressions in lattice key text

Folks:

delta <- 1:5

I would like to put 5 separate lines of text of the form "10 %+-%
delta[i]"
into a lattice key legend, where ""%+-%" is the plotmath
plus/minus symbol
and delta[i] is the ith value of delta.

The construct:

lapply(delta,function(d)bquote(10%+-%.(d)))

appears to produce a list of expressions of the correct form, and, indeed,
if I assign the above to (a list!) test,

plot(0:1,0:1)
text(.5,.5,test[[1]])

produces the correctly formatted plotmath expression. However, note that I
have to use test[[1]] to extract the expression; test[1] doesn't work (it is
a list containing an expression, not an expression) -- and therein may lie
the problem. For if I try to use the above expression as the lab component
of the text component in key, e.g. by

xyplot(....,
key = list( text = list(lab
lapply(delta,function(d)bquote(10%+-%.(d))),...),...)


I get an error:

Error in fun(key = list(text = list(lab = list(10 %+-% 1, 10 %+-% 2 : 
  first component of text has to be vector of labels


So how should I do this?? I suspect it's simple, but I just can't figure
it
out.

Note: I'd be happy to supply reproducible code if needed. Just complain and
I'll do so.

Thanks.


Bert Gunter
Genentech Nonclinical Statistics

Bert Gunter said the following on 11/15/2007 1:12 PM:
> Folks:
> 
> delta <- 1:5
> 
> I would like to put 5 separate lines of text of the form "10 %+-%
delta[i]"
> into a lattice key legend, where ""%+-%" is the plotmath
plus/minus symbol
> and delta[i] is the ith value of delta.
> 
> The construct:
> 
> lapply(delta,function(d)bquote(10%+-%.(d)))
> 
> appears to produce a list of expressions of the correct form, and, indeed,
> if I assign the above to (a list!) test,
> 
> plot(0:1,0:1)
> text(.5,.5,test[[1]])
> 
> produces the correctly formatted plotmath expression. However, note that I
> have to use test[[1]] to extract the expression; test[1] doesn't work
(it is
> a list containing an expression, not an expression) -- and therein may lie
> the problem. For if I try to use the above expression as the lab component
> of the text component in key, e.g. by
> 
> xyplot(....,
> key = list( text = list(lab >
lapply(delta,function(d)bquote(10%+-%.(d))),...),...)
> 
> 
> I get an error:
> 
> Error in fun(key = list(text = list(lab = list(10 %+-% 1, 10 %+-% 2 : 
>   first component of text has to be vector of labels
> 
> 
> So how should I do this?? I suspect it's simple, but I just can't
figure it
> out.
> 
> Note: I'd be happy to supply reproducible code if needed. Just complain
and
> I'll do so.
> 
> Thanks.
> 
> 
> Bert Gunter
> Genentech Nonclinical Statistics
Hi, Bert,

This is how I've done it in the past. Perhaps there's a better way:

library(lattice)

delta <- 1:5
expr <- paste("10%+-%", delta, sep = "", collapse =
",")
expr <- paste("expression(", expr, ")", sep =
"")
expr <- eval(parse(text = expr))

xyplot(0 ~ 0 | factor(delta),
        key = list(text = list(expr)),
        ## bonus: adding it to the strip
        strip = function(factor.levels, ...) {
          strip.default(factor.levels = expr, ...)
        })


Thanks,

--sundar

On Nov 15, 2007 7:12 PM, Bert Gunter <gunter.berton at gene.com>
wrote:
>
> Folks:
>
> delta <- 1:5
>
> I would like to put 5 separate lines of text of the form "10 %+-%
delta[i]"
> into a lattice key legend, where ""%+-%" is the plotmath
plus/minus symbol
> and delta[i] is the ith value of delta.
>
> The construct:
>
> lapply(delta,function(d)bquote(10%+-%.(d)))
>
> appears to produce a list of expressions of the correct form, and, indeed,
> if I assign the above to (a list!) test,
>
> plot(0:1,0:1)
> text(.5,.5,test[[1]])
>
> produces the correctly formatted plotmath expression. However, note that I
> have to use test[[1]] to extract the expression; test[1] doesn't work
(it is
> a list containing an expression, not an expression) -- and therein may lie
> the problem. For if I try to use the above expression as the lab component
> of the text component in key, e.g. by
>
> xyplot(....,
> key = list( text = list(lab >
lapply(delta,function(d)bquote(10%+-%.(d))),...),...)
>
>
> I get an error:
>
> Error in fun(key = list(text = list(lab = list(10 %+-% 1, 10 %+-% 2 :
>   first component of text has to be vector of labels
>
>
> So how should I do this?? I suspect it's simple, but I just can't
figure it
> out.
as.expression(lapply(delta, ...))

seems to produce the right sort of vector.

-Deepayan
>
> Note: I'd be happy to supply reproducible code if needed. Just complain
and
> I'll do so.
>
> Thanks.
>
>
> Bert Gunter
> Genentech Nonclinical Statistics
>
> ______________________________________________
> 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.
>