From Nathan.Weeks at ARS.USDA.GOV  Wed Jun 28 19:11:01 2017
From: Nathan.Weeks at ARS.USDA.GOV (Weeks, Nathan)
Date: Wed, 28 Jun 2017 17:11:01 +0000
Subject: [Rd] regexec() bug in R 3.4.0
Message-ID: <25769b0b70394202831721536dac853f@DM2PR0204MB0122.001f.mgd2.msft.net>

Hi,

In R 3.4.0, the "Pattern Matching and Replacement" documentation that describes regexec(), gregexpr(), etc. states that the "text" argument to regexec is a character vector, "or an object which can be coerced by as.character to a character vector":

     regexec(pattern, text, ignore.case = FALSE, perl = FALSE,
             fixed = FALSE, useBytes = FALSE)

     x, text: a character vector where matches are sought, or an object
         which can be coerced by as.character to a character vector.
         Long vectors are supported.

However, in R 3.4.0, this coercion doesn't seem to automatically occur for the text argument of regexec(), whereas it does for gregexpr(), regexpr(), etc:

============================================================
$ R --vanilla

R version 3.4.0 (2017-04-21) -- "You Stupid Darkness"
Copyright (C) 2017 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

...
> text <- as.factor("foobar")
> regexec("foo", text)
Error in regexec("foo", text) : invalid 'text' argument
> regexec("foo", as.character(text))                                                                                                             [[1]]                                                                                                                                            [1] 1
attr(,"match.length")
[1] 3
attr(,"useBytes")
[1] TRUE

> gregexpr("foo", text)                                                                                                                          [[1]]
[1] 1
attr(,"match.length")
[1] 3
attr(,"useBytes")
[1] TRUE
============================================================

Is this a documentation issue, a bug in regexec(), or am I misunderstanding how it's supposed to behave?

Thanks,

--
Nathan Weeks
IT Specialist
USDA-ARS Corn Insects and Crop Genetics Research Unit
Crop Genome Informatics Laboratory
Iowa State University







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[Rd] regexec() bug in R 3.4.0
Weeks, Nathan