[R] expression(), mixed symbols and evaluated objects

[Duncan Murdoch]

On 10/03/2010 8:52 AM, Markus Loecher wrote:
> Is it possible to mix symbols and evaluated objects inside the expression()
> function ?
> The following example shows what I am trying to achieve:
>
> for (m in 1:3) {
>     plot(1:10); #just a place holder for the real plots
>     title(expression(y = m * lambda));
> }
>
> I want to actually evaluate the variable m but keep lambda as a symbol in
> the title.
> I tried to wrap an eval() around various subparts of the expression but to
> no avail.
>
> Going further, I ideally would like to mix text into the expression as well.
>
> Any help would be appreciated.
Use bquote.  It returns an expression after evaluating only the parts 
wrapped in ".()".  For example,

for (m in 1:3) {
    plot(1:10); #just a place holder for the real plots
    title(bquote(y == .(m) * lambda));
}

Duncan Murdoch