Strings & Expressions in Plot Titles, Labels etc

Question

I am trying to paste together user a user provided string and a fixed string in a plot title.

A simple case that works, of course:

userTitle <- "user title" # Example 1
fullTitle <- paste(userTitle, ": Results", sep = "")
plot(1:10, main = fullTitle)

But what if the user's title contains an expression? Here's some things I've tried:

# This works, but doesn't include the fixed string # Example 2
userTitle <- expression(italic(Genus)~italic(species)) # EDIT: this was missing
fullTitle <- bquote(.(userTitle))
plot(1:10, main = fullTitle)

Try to add the fixed string. Some things that don't quite work:

fullTitle <- bquote(.(userTitle)~':'~Results) # Example 3
plot(1:10, main = fullTitle) # title missing .(userTitle)

fullTitle <- bquote(paste("Results:", .(userTitle))) # Example 4
plot(1:10, main = fullTitle) # title missing .(userTitle)

But this example, from here works just fine [EDIT: link was to wrong question].

x<- 232323
plot(1:10, main = bquote(paste(ARL[1], " curve for ", S^2, "; x=",.(x))))

My Example 4 looks pretty much exactly this last one, but doesn't behave the same. There are so many combos of bquote, expression, substitute and I've looked at a lot of answers, but I am likely missing something really small. Any advice on how to get the user string and fixed string together if the user string contains an expression in this case? Thanks.

Answer 1

I can do it with a formula:

userTitle <- italic(Genus)~italic(species) 
plot(1, 1., main=substitute( userTitle*": Results" , 
                              list(userTitle=userTitle) ) )

And now with an expression:

userTitle <- expression( italic(Genus)~italic(species) )
plot( 1, 1, main= bquote(.(eval(userTitle))*":"~Results) )