[R] New line in caption with math symbols embedded in expression (paste(

[Izmirlian, Grant (NIH/NCI) [E]]

This is beautiful. Thanks!
G

-----Original Message-----
From: Rui Barradas <ruipbarradas using sapo.pt> 
Sent: Thursday, February 18, 2021 2:10 PM
To: Izmirlian, Grant (NIH/NCI) [E] <izmirlig using mail.nih.gov>; r-help using r-project.org
Subject: Re: [R] New line in caption with math symbols embedded in expression (paste(

Hello,

First of all the plotmath in your code doesn't need paste, expression alone will do it.

I am not sure that the following is what you want. I create the caption beforehand, in order to make the plotting code simpler.
The asterisks/tildes make less/more space between the text line's elements.


e <- expression(
   atop(
     P * "(" * FDP ~ ">" ~ alpha * ") " ~
       "for 'FDR' and 'Auto' FDP control method, vs '" *
       m * "' at levels of 'eff size' (col) and '" *
       p[1] * "' (row)" ~ "and",
     "a new line" ~
       bar(x) == sum(frac(x[i], n), i==1, n)
   )
)

p <- ggplot(data=DAT, aes(x=X)) + geom_point(aes(y=Y)) + 
geom_line(aes(y=Y.p))
p <- p + labs(caption = e)
p <- p + theme(plot.caption = element_text(hjust = 0))
p


Hope this helps,

Rui Barradas
Às 17:37 de 18/02/21, Izmirlian, Grant (NIH/NCI) [E] via R-help escreveu:
> ## I am using ggplot and trying to produce a caption containing math symbols. I need to
> ## add a second line. I did a fair amount of googling for answers. This one seemed like
> ## it would answer my question as it is nearly exactly my problem, except there is only
> ## one argument to the paste function. Note that my example is a complete minimal
> ## example, just a scatterplot with a line, and the caption content seems to not have
> ## anything to do with the plot. That is of course, intentional.
> ##
> ## https://stackoverflow.com/questions/13223846/ggplot2-two-line-label-with-expression
> 
> library(ggplot2)
> X <- 10*runif(100)
> Y <- 2*X + rnorm(100, sd=2)
> fit <- lm(Y~X)
> Y.p <- predict(fit, newdata=data.frame(X=X))
> DAT <- data.frame(X=X)
> 
> ## without a newline
> p <- ggplot(data=DAT, aes(x=X)) + geom_point(aes(y=Y)) + geom_line(aes(y=Y.p))
> p <- p + labs(caption=expression(paste(P,"(",FDP,">", alpha,") ",
>                          "for 'FDR' and 'Auto' FDP control method, vs '", m,
>                          "' at levels of 'eff size' (col) and '", p[1], "' (row)")))
> p <- p + theme(plot.caption = element_text(hjust = 0))
> 
> ## newline, method 1, just add a new component of paste containing "\n" somewhere in the middle
> p <- ggplot(data=DAT, aes(x=X)) + geom_point(aes(y=Y)) + geom_line(aes(y=Y.p))
> p <- p + labs(caption=expression(paste(P,"(",FDP,">", alpha,") ",
>                          "for 'FDR' and 'Auto' FDP control method, vs '", m,
>                          "' at levels of 'eff size' (col) and '", p[1], "' (row)",
>                          "and \n a new line")))
> p <- p + theme(plot.caption = element_text(hjust = 0))
> 
> ## doesn't work because the newline affects only the last component of paste. It looks like new line
> ## works if the line is long enough, but the newline character is being parsed until the individual
> ## arguments to paste are parsed for math symbols but prior to pasting the components together. prior
> ## to pasting all arguments. I can't imagine why this would be the desired behavior. When the value of a
> ## caption argument is expression(paste(s1, s2, s3, ...)) then parsing for a newline character should
> ## occur after the components are pasted together, right?
> 
> ## newline, method 2, enclose paste in another paste and add the new line as the second argument of the
> ## outer paste
> p <- ggplot(data=DAT, aes(x=X)) + geom_point(aes(y=Y)) + geom_line(aes(y=Y.p))
> p <- p + labs(caption=expression(paste(paste(P,"(",FDP,">", alpha,") ",
>                          "for 'FDR' and 'Auto' FDP control method, vs '", m,
>                          "' at levels of 'eff size' (col) and '", p[1], "' (row)"),
>                          "and \n a new line")))
> p <- p + theme(plot.caption = element_text(hjust = 0))
> 
> ## which has the same behavior
> 
> 
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