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rexpressionsubscriptsuperscript

Using a string variable in expression for R for subscript/superscript

We can use subscript or superscript in a plot title in R using the following

plot(1,1, main=expression('title'^2))  #superscript

plot(1,1, main=expression('title'[2])) #subscript

However, what if I want to use a string variable in expression. For example,

my_string="'title'^2"

plot(1,1, main=expression(my_string))

Clearly, this doesn't work and the plot title just becomes my_string rather than title^2.

Is it possible to use a string variable inside expression?

Thanks, Brij.

Solution

  • In order to make an expression from a string, you need to parse it. Try this

    my_string <- "'title'^2"
my_title <- parse(text=my_string)
plot(1,1, main=my_title)

    If you just wanted to swap out certain parts of the expression with a string value, you can use something like bquote

    my_string <- "title"
my_title <- bquote(.(my_string)^2)
plot(1,1, main=my_title)