[Rd] "+" operator on characters revisited
spencer.graves at structuremonitoring.com
Sun Jan 23 18:10:39 CET 2011
On 1/23/2011 8:50 AM, peter dalgaard wrote:
> On Jan 22, 2011, at 21:08 , Vitalie S. wrote:
>> The only definite argument occurred in the thread against "+" operator
>> was the lack of commutativity (as if one have to prove algebraic
>> theorems in R).
> I think the real killer was associativity, combined with coercion rules:
> Is "x"+1+2 supposed to be equal to "x12" or "x3"?
Excellent: This seems like a good reason to follow Python:
Allow "a+b" with a character vector "a" only if "b" is also a character
vector (or factor?).
This example raises another question: If we allow "a+b" for "a"
and "b" both character vectors (and give an error if one is numeric),
what do we do with factors? If "a" is a factor, return a factor?
More information about the R-devel