Re: [Rd] Argument recycling in substring()

From: Hadley Wickham <>
Date: Fri, 04 Jun 2010 06:15:16 -0500

> According to its man page substring() "expands (its) arguments
> cyclically to the length of the longest _provided_ none are of
> zero length".
> So, as expected, I get an error here:
>  > substring("abcd", first=2L, last=integer(0))
>  Error in substring("abcd", first = 2L, last = integer(0)) :
>    invalid substring argument(s)
> But I don't get one here:
>  > substring(character(0), first=1:2, last=3L)
>  character(0)
> which is unexpected.

If you want a set of string functions that strive to be simple and consistent you might want to look at the stringr package. And since it's a new package, I'm very keen to remove any inconsistencies.


Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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