Subscripts in R when adding other text

Question

How would you add a subscript to one particular word of a title in R? For example, suppose the title is \"A_2 and B_2.\" How would you add these two subscripts?

Answer 1

You do not need paste (or quotes for that matter) at all:

expression( A[2]~and~B[2] )

Test:

plot(1,1, main=expression( A[2]~and~B[2] ) )

The syntactic principle is that tildes (which creates a space) and asterisks (non-space plotmath separator) are used to separate items and that no quotes are needed unless you are using a plotmath function name .... such as wanting the word "paste" or "sqrt" to appear in the displayed version of the expression.