[Rd] Perl question

Dirk Eddelbuettel edd@debian.org
Fri Feb 21 21:02:03 2003

> I'm working on the installer code, but I don't know Perl well enough.
> What is a good Perl equivalent of the R statement
>  if ( s %in% c('string1', 'string2', 'string3') )  ...
> I can do it with 
>  if (s == "string1" || s == "string2" || s == "string3")  ...

You probably wanted 'eq' instead of '=='.  The reg.exp. version is

    if (s =~ m/(string1|string2|string3)/o) {  ...

where the trailing o makes it supposedly less expensive (regexp 
only compiled once, see man perlop).

> but I've got a feeling there's a better way to do it using associative
> arrays.  

You could use grep and map on assoc. arrays, but IMHO the above is easier.

> The real example will have about a dozen fixed strings that I want to
> search a few thousand times.

That may be worth profiling / timing.

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