[R] Trouble with expression() in R-win 2.0.1

[Deepayan Sarkar]

On Friday 25 March 2005 20:26, Ronnen Levinson wrote:
>    Hi.
>    The following statement works fine in R-win 1.8.0, but yields a
> syntax error in R-win 2.0.1 (and possibly in other versions after
> 1.8.0):
>
>      plot(c(1,2),main=expression(a==b==c))
>
>    I  note  that  the  following workaround executes successfully in
> both versions of R...
>
>      plot(c(1,2),main=expression(a*"="*b*"="*c))
>
>    ...but  I don't really understand why the first version works in
> 1.8.0 and not in 2.0.1.

The relevant NEWS entry says:

    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.

i.e., you want

plot(c(1,2),main=expression(a=={b==c}))

Deepayan