[R] Fast multiple match function

William Dunlap wdunlap at tibco.com
Tue Apr 7 00:49:28 CEST 2015

split() might help, but you should give a more complete
explanation of your problem.

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Mon, Apr 6, 2015 at 1:56 PM, Keshav Dhandhania <kshav.91 at gmail.com>

> Hi,
> I know that one can find all occurrences of x in a vector v by doing
> > which(x == v).
> However, if I need to do this again and again, where v is remaining the
> same, then this is quite inefficient. In my particular case, I need to do
> this millions of times, and length(v) = 100 million.
> Does anyone have suggestion on how to go about it?
> I know of a package called fmatch that does the above for the match
> function. But they don't handle multiple matches.
> Thanks
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