[R] if syntax

Adaikalavan Ramasamy ramasamy at cancer.org.uk
Sun Jun 20 18:22:34 CEST 2004


This has been discussed several times on this list. Note that line 2 of
paragraph 2 of help("if") says the following :

" In particular, you should not have a newline between '}' and 'else' to
avoid a syntax error in entering a 'if ... else' construct at the
keyboard or via 'source'. "


On Sun, 2004-06-20 at 17:00, ivo_welch-Rstat at mailblocks.com wrote:
> I ran into an interesting oddity of R,
>     if (0) { print(1); }
>     else  { print(2); }
>  is a syntax error, while
>     if (0) { print(1); } else  { print(2); }
> or
>     if (0) { print(1);
>     } else  { print(2); }
>   is not.  I presume it has to do with the duality of the newline 
> functioning as an end of command (;) character, though it still seems a 
> bit odd, and it took me a while to figure out what was wrong.  I 
> eventually figured out that to resolve this ambiguity, I would guess 
> that ifelse() would be a preferred function.
> 
> I wanted to look up the internal R documentation for if via "?if", but 
> this does not work.  making the latter work would be a good idea.
> 
> regards,  /iaw
> ---
> ivo welch
> professor of finance and economics
> brown / nber / yale
> 
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