Specifying text in a base R plot() with formatting such as italics / bold font / newline usually involves one or more of the following functions:
paste()
expression()
atop()
substitute()
italic()
Is there an intuitive explanation for the differences between these functions and when best to apply them?
What you're referring to is the plotmath syntax.
To start off, let's make it clear that for a plotmath expression to be interpreted as such, you tell R it's an "expression" and that is why you need expression().
So any time you want to use special symbols or formatting, like italic() and atop(), it's actually a part of plotmath and so you need to wrap it in an expression. eg:
plot(0, main = expression(atop(over,italic(under))))
If you've tried out ?italic or ?atop, you've probably noticed it takes you straight to the plotmath manual page, where a bunch of other functions are listed.
What about substitute() ? Well in my previous example, you'll notice I used strings directly to write 'over' and 'under', without putting them within quotes. This is because of the special expression() environment.
So if you need to put whatever is inside a variable in your text (rather than the variable name) then you put your expression inside a substitute() and give it the arguments. eg:
plot(0, main = substitute(atop(oo,italic(under))), list(oo='over2')))
Note that we don't put substitute around the expression block but replace it entirely.
Finally, where does paste() come in all this ? Well, paste is the glue (pun intended) with any text not dealt with by plotmath.
So if you need text before or after math symbols (or formatted text), you paste() things together within the expression (or substitute) environment. eg :
plot(0, main = substitute(paste("b4", atop(oo,italic(under)), aft),
list(oo='over', aft = 'after3')))
As before, if you want to paste the content of a variable, you need substitute.
And Voilà that's most of the plotmath you'll ever need!
For any other symbols, or functions, have look at ?plotmath
In the output of the following code,
curve((1+exp(-1*x))^-1,
xlim=c(-10,10),ylim=c(0,1),
main="Logistic function",xlab=expression ("x"[t-d]),
ylab=expression ("G"("x"[t-d],gamma,c)))
In the y-axis label, how to place a semi-colon in between immediately before the gamma instead of a comma?
In this case you just need to think of the semicolon as text rather than a special character you can do
ylab=expression ("G"("x"[t-d]~";"~gamma,c))
or you can use * rather than ~ if you want less space.
In my data.frame I would like to add two variables, "A" and "B", whose values contain respectively an n with the i subscript and an n with the s subscript.
As I have understood so far, it's not possible to specify an expression for the values of a variable, and hence to add special characters it's necessary to use unicode symbols. Some of this unicodes work in R, as for example the greek letter "mu", identified with the unicode \U00B5, or numeric subscripts, as you can see in this reprex in your R console:
x <- data.frame("A" = c("\U00B5"),
"B" = c("B\U2082"))
print(x)
These unicodes work also if I decide to put this variable in a ggplot() object, because I will display the correct symbol ("mu" for example) on the axis text or the facets.
The problem is that when I do the same for the subscripts of i (unicode: \U1D62) and s (unicode: \u209B), R doesn't recognise the unicode and prints the whole string inside the variable name.
Do you know how I can resolve this issue and if this unicode works on every operating system?
Thanks
Is there a reason you can't use the expression() function? It seems this would solve your problem (at least concerning greek letters).
Here is the site i used to learn how to input greek letters into my R/ggplot-legends.
https://stats.idre.ucla.edu/r/codefragments/greek_letters/
Altough it is not exactly the answer you look for, i still hope it helps!
If you are on Windows 10 recently updated with as of April 2018 Update:
Use the Windows key + '.' (e.g. hold together Windows Key plus period) in your text editor. This brings up Microsoft Emoji keyboard.
Select the Greek letters variable for your script.
The R Console will not accept the Greek letters as variables directly but only the from the editor script. Some of the Greek letters don't translate to English (like "µ" or "ß".) You can paste and copy them from ls() output to access. You may be able to use some math symbols as well for variable names. I can't however, get this to work with source(). That must be a text encoding problem.
I want to put Capitalomega with index DE and k label:
and then ı want to show on the y axis label? How to do them?
Generally you can use tex symbols in Veusz. Therefore, you can write \Omega_{DE} and \Omega_{k} for your request. See details here (Sec. 2.4 Text).
Veusz understands a limited set of LaTeX-like formatting for text. There are some differences (for example, "10^23" puts the 2 and 3 into superscript), but it is fairly similar. You should also leave out the dollar signs. Veusz supports superscripts ("^"), subscripts ("_"), brackets for grouping attributes are "{" and "}".
Supported LaTeX symbols include: \AA, \Alpha, \Beta, \Chi, \Delta, \Epsilon, \Eta, \Gamma, \Iota, \Kappa, \Lambda, \Mu, \Nu, \Omega, \Omicron, \Phi, \Pi, \Psi, \Rho, \Sigma, \Tau, \Theta, \Upsilon, \Xi, \Zeta, \alpha, \approx, \ast, \asymp, \beta, \bowtie, \bullet, \cap, \chi, \circ, \cup, \dagger, \dashv, \ddagger, \deg, \delta, \diamond, \divide, \doteq, \downarrow, \epsilon, \equiv, \eta, \gamma, \ge, \gg, \in, \infty, \int, \iota, \kappa, \lambda, \le, \leftarrow, \lhd, \ll, \models, \mp, \mu, \neq, \ni, \nu, \odot, \omega, \omicron, \ominus, \oplus, \oslash, \otimes, \parallel, \perp, \phi, \pi, \pm, \prec, \preceq, \propto, \psi, \rhd, \rho, \rightarrow, \sigma, \sim, \simeq, \sqrt, \sqsubset, \sqsubseteq, \sqsupset, \sqsupseteq, \star, \stigma, \subset, \subseteq, \succ, \succeq, \supset, \supseteq, \tau, \theta, \times, \umid, \unlhd, \unrhd, \uparrow, \uplus, \upsilon, \vdash, \vee, \wedge, \xi, \zeta. Please request additional characters if they are required (and exist in the unicode character set). Special symbols can be included directly from a character map.
Other LaTeX commands are supported. "\" breaks a line. This can be used for simple tables. For example "{a\b} {c\d}" shows "a c" over "b d". The command "\frac{a}{b}" shows a vertical fraction a/b.
Also supported are commands to change font. The command "\font{name}{text}" changes the font text is written in to name. This may be useful if a symbol is missing from the current font, e.g. "\font{symbol}{g}" should produce a gamma. You can increase, decrease, or set the size of the font with "\size{+2}{text}", "\size{-2}{text}", or "\size{20}{text}". Numbers are in points.
Various font attributes can be changed: for example, "\italic{some italic text}" (or use "\textit" or "\emph"), "\bold{some bold text}" (or use "\textbf") and "\underline{some underlined text}".
Example text could include "Area / \pi (10^{-23} cm^{-2})", or "\pi\bold{g}".
Veusz plots these symbols with Qt's unicode support. You can also include special characters directly, by copying and pasting from a character map application. If your current font does not contain these symbols then you may get a box character.
In addition to the answer OmG posted, you can also directly enter the character (via a character map application or copy and paste), as Veusz supports unicode characters.
I want to write \sigma^2_i using unicode I can get two-thirds of the way there with:
"\u03C3\U00B2"
I can't for the life of me figure out how to add subscript. According to this site where I got the unicode for superscript 2 the correct unicode for subscript i is "\u1D62", but in R this does not print subscript i.
I know that for text in plots you can use expression, but this is not for a plot, so expression does not work.
Any help would be appreciated.
edit: it appears that using cat evaluates unicode in cases when just printing doesn't necessarily evaluate the unicode. I still don't understand why the unicode characters are inconsistent. Per this website the unicode character for subscript k is "\u2096", but cat("\u2096") prints a thick |