[R] Substitute in legend

[Uwe Ligges]

Peter Dalgaard BSA wrote:

> partha_bagchi at hgsi.com writes:
> 
> 
>>I tried to use substitute in legend as follows:
>>
>>pval <- 0.04
>>plot(0)
>>legend(1,0.5,substitute(hat(theta) == p, list(p = pval)))
>>
>>For some reason the legend is repeated 3 times. 
>>
>>Any suggestions or is this a bug?
> 
> 
> It's a bug. The code is looking at length(legend), but that is not the
> number of legends when mode "call" objects are concerned. A workaround
> is 
> 
> legend(1,0.5,as.expression(substitute(hat(theta) == p, list(p = pval))))

Or more general:

  do.call("expression",
    list(substitute(hat(theta) == p, list(p = pval))))

This way you can include several substitute() calls within that list, to 
allow an expression of length > 1 which is frequently required for legends.


I think it is not really a bug, because this is documented,
but inserting
  if(is.call(legend))
    legend <- as.expression(legend)
would not break anything, AFAICS.

Uwe Ligges