[R] Changes in expression in R 2.0.1

[Uwe Ligges]

Ale. .iberna wrote:
> Hello!
> 
> 
> 
> plot(1:10,main=expression(1 <= "m" <= 5))
> 
> The above command works perfectly in R 1.9.1 but returns an error in R 2.0.1
> 
> 
> 
> This is documented in NEWS for R 2.0.0 (or ONEWS in R 2.0.1) and it is said:
> 
> o   R no longer accepts associative use of relational operators.
>      That is, 3 < 2 < 1 (which used to evalute as TRUE!) now causes
>      a syntax error.  If this breaks existing code, just add
>      parentheses -- or braces in the case of plotmath.
> 
> 
> 
> It is true that the following command does not give en error, however, I do 
> not what the extra brackets in the plot:
> 
> plot(1:10,main=expression(1 <= ("m" <= 5)))
> 
> 
> 
> Is it possible to have this thing plotted with the same look as in R 1.9.1?
> I apologize if the instruction are in NEWS, since I am not sure how to 
> interpret exactly this section (especially : "just add parentheses -- or 
> braces in the case of plotmath".

A good dictionary should tell you that {} rather than () is meant with 
"braces":

   plot(1:10,main=expression(1 <= {"m" <= 5}))

You have to group it syntactically, that's all.

Uwe Ligges


> 
> 
> Thank you in advance for any replies!
> 
> Ales Ziberna
>