[R] italics letter in roman string

[Gabor Grothendieck]

Sorry, legend= was omitted:

plot(1:10)
legend("topleft", legend = This ~ study ~ italic(n) == 3293)

On 3/18/07, Chabot Denis <chabotd at globetrotter.net> wrote:
> Thank you Marc, Jim and Gabor,
>
> I like the solution with "expression", nice and simple. Gabor, your
> solution did not work, probably just a matter of putting the text
> inside an expression?
>
> However it would be nice if the help system pointed to it. A search
> on "italics" brought me nothing, one on "italic" gave me 4 hits, none
> useful. And reading the help on plotmath, I found no mention of italic
> (). Where can we suggest additions to the help system?
>
> I must plead guilty to have forgotten a RSiteSearch before posting. I
> just did and I think I might have figured out something out there.
> But your answers were nice and to the point!
>
> Cheers,
>
> Denis
> Le 07-03-17 à 23:30, Marc Schwartz a écrit :
>
> > On Sat, 2007-03-17 at 21:56 -0500, Marc Schwartz wrote:
> >> On Sat, 2007-03-17 at 22:01 -0400, Chabot Denis wrote:
> >>> Hi,
> >>>
> >>> As part of the legend to a plot, I need to have the "n" in italics
> >>> because it is a requirement of the journal I aim to publish in:
> >>> "This study, n = 3293"
> >>>
> >>> Presently I have:
> >>> legend(20, 105, "This study, n = 3293", pch=1,  col=rgb(0,0,0,0.5),
> >>>                  pt.cex=0.3, cex=0.8, bty="n")
> >>>
> >>> I suppose I could leave a blank in place of the "n", then issue a
> >>> text call where I'd use font=3 for a single letter, "n". But it will
> >>> be tricky to find the exact location to use.
> >>>
> >>> Is there a way to switch to font=3 just for one letter within a
> >>> string?
> >>>
> >>> Thanks in advance,
> >>>
> >>> Denis Chabot
> >>
> >> Denis,
> >>
> >> Try something like this:
> >>
> >> plot(20, 100)
> >>
> >> leg <- legend(20, 105, "This study,    = 3293", pch = 1,
> >>               col=rgb(0,0,0,0.5), pt.cex = 0.3, cex = 0.8,
> >>               bty = "n")
> >>
> >> text(leg$text$x + strwidth("This study, ", cex = 0.8),
> >>      leg$text$y, "n", font = 3, cex = 0.8, adj = c(0, 0.5))
> >>
> >>
> >> Note that legend returns a list structure, which contains the x and y
> >> coordinates of the start of the text strings that are plotted. So
> >> I get
> >> that information for your line of text.
> >>
> >> Next, I use strwidth() to calculate, in user coordinates, the
> >> length of
> >> the characters preceding the 'n', including spaces.  We add that
> >> distance to the x coordinate returned in the legend call.
> >>
> >> I also use the 'adj' argument in the text() call, so that it is in
> >> synch
> >> with the same parameters in legend() for alignment with the other
> >> letters.
> >>
> >> See ?strwidth for more information.
> >>
> >> You may have to tweak the horizontal spacing of the 'n' a bit,
> >> depending
> >> upon the rest of your graph.
> >
> > Denis,
> >
> > I thought of another approach, using plotmath.
> >
> > First, create a text expression, specifying that the 'n' should be
> > italicized. Then use that expression in the legend() call.
> >
> > txt <- expression(paste("This study, ", italic(n), " = 3293"))
> >
> > plot(20, 100)
> >
> > legend(20, 105, txt, pch = 1, col=rgb(0,0,0,0.5),
> >        pt.cex = 0.3, cex = 0.8, bty = "n")
> >
> >
> > That's easier that the first solution.  See ?plotmath
> >
> > HTH,
> >
> > Marc Schwartz
> >
> >
>
>