> On Mar 20, 2017, at 4:42 AM, Troels Ring <[email protected]> wrote:
>
> Dear friends - here is an example of something that I find annoying
>
> library(ggplot2)
> DDF <- data.frame(x=x<-seq(1,10),y=x^2)
> G <- ggplot(data=DDF,aes(x=x,y=y)) + geom_point()
> GG<-G+ylab(expression(paste("Total ",CO[2]," halved")))
> GG
> GG+annotate("text",x=5,y=50,label=expression(paste("Total ",CO[2]," halved")))
>
> On my system, R version 3.3.2 (2016-10-31) Windows - the third line produces
> the wanted formatting of CO2 with "2" lowered - while the last line produces
> an error "invalid 'type' (expression) of argument" - with exactly the same
> string - how comes?
>
> Beautiful ggplot is not exactly low in documentation but finding the right
> stuff is not always easy (for me:-))
As the Posting Guide recommends, the question should include the complete text
of the error message:
"Error in stats::complete.cases(df[, vars, drop = FALSE]) :
invalid 'type' (expression) of argument"
In this case, however I find that message completely opaque and the results of
traceback() likewise uninformative, so going back to the help pages, always a
good place to start, notice that the last example on `?annotate` is isomorphic
to you problem, so try using the curiously unlisted `parse`-parameter to
annotate. The parse parameter according to the documentation is being passed to
`layer`, but `?layer` doesn't describe a parse parameter so I think it's a
defect (somewhere) in the ggplot2 help pages.
GG + annotate("text", x=5, y=50, label = "Total~CO[2]~halved", parse=TRUE)
I have removed the call to `paste` since I find that it's use inhibits learning
to use expressions most economically. I think it's better to use the tilde
rather than assembling a mishmash of quoted and unquoted sub-expressions.
--
David.
>
> Best wishes
> Troels Ring, MD
> Aalborg, Denmark
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA
______________________________________________
[email protected] mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
