Include text control characters in plotmath expressions

Question

Is there any way to get control characters for text strings, e.g. "\n" for newline evaluated inside a plotmath expression, or vice versa. In the following example, I would like to combine:

some character text
text control character (newline)
substitute a variable name
include a plotmath expression

After reading this question I can get most of the way there with substitute, but the newline character is not evaluated. I am now going round in circles and confusing myself with plotmath, parse, bquote and substitute. In the help page for plotmath it says

Control characters (e.g. \n) are not interpreted in character strings in plotmath, unlike normal plotting.

Does this mean it really is impossible?

lab = "some data"
form = "Exponential"
x = 1:10
y = x^2


plot( x , y , type = "b" )
title( main = substitute( paste( "Plot of " , phi , " of: "  , lab , "\nFunctional form: " , form ) , list(lab = lab , form = form ) ) , adj = 0 )

enter image description here

agstudy · Accepted Answer · 2013-03-08 18:05:56Z

12

As you have figured plotmath does not support newlines within, but you can use mtext with bquote, to write each line. For example I create a list of lines :

Lines <- list(bquote(paste( "Plot of " , phi , " of: "  , .(lab))),
              bquote(paste("Functional form: " , .(form)))

mtext(do.call(expression, Lines),side=3,line=1:0)

enter image description here

answered Mar 8, 2013 at 18:05

agstudy

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1 Comment

Simon O'Hanlon Over a year ago

Your solution works just perfectly! Thank you so much for wading through the quagmire of bquote and math/text expressions for me! +1

Community · Accepted Answer · 2017-05-23 10:27:11Z

5

For the sake of completeness, here's another solution using unicode and no expressions (adapted from here and here):

plot(x, y, type="b")
title(main=paste("Plot of \u03A6 of:", lab, "\nFunctional form:", form), adj=0)

enter image description here

edited May 23, 2017 at 10:27

CommunityBot

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answered Mar 9, 2013 at 8:11

plannapus

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3 Comments

Simon O'Hanlon Over a year ago

+1 Thanks. This is a nice straightforward solution. I didn't even know it was possible to include unicode characters like this. If it were possible to split credit for accepted answers here I would. Thanks!

plannapus Over a year ago

As a bit of warning though, some platform/devices don't render all unicode character properly, so it is a good thing that you have agstudy and baptiste solutions as well to fall back on when it happens. See this blog post for some additional tips.

Simon O'Hanlon Over a year ago

Ah, thank you for the heads up. You will have probably saved me some additional future headaches when I can't recreate your solution. Thanks again, and thanks for the link.

baptiste · Accepted Answer · 2013-03-09 08:39:29Z

4

if you use grid graphics, then the following grob can be useful to space the lines according to their height,

library(devtools)
source_gist(2732693)
grid.expr(as.expression(Lines))

(using agstudy's Lines)

answered Mar 9, 2013 at 8:39

baptiste

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