>>>>> "David" == David Forrest <[EMAIL PROTECTED]>
>>>>> on Tue, 22 Mar 2005 15:02:20 -0600 (CST) writes:
David> According to help(sub), the ^ should match the
David> zero-length string at the beginning of a string:
yes, indeed.
David> sub('^','var',1:3) # "1" "2" "3"
David> sub('$','var',1:3) # "1var" "2var" "3var"
David> # This generates what I expected from the first case:
David> sub('^.','var',11:13) # "var1" "var2" "var3"
there are even more fishy things here:
1) In your cases, the integer 'x' argument is auto-coerced to
character, however that fails as soon as 'perl = TRUE' is used.
> sub('^','v_', 1:3, perl=TRUE)
Error in sub.perl(pattern, replacement, x, ignore.case) :
invalid argument
{one can argue that this is not a bug, since the help file asks
for 'x' to be a character vector; OTOH, we have
as.character(.) magic in many other places, i.e. quite
naturally here;
at least perl=TRUE and perl=FALSE should behave consistently.}
2) The 'perl=TRUE' case behaves even more problematically here:
> sub('^','v_', LETTERS[1:3], perl=TRUE)
[1] "A\0e" "B\0J" "C\0S"
> sub('^','v_', LETTERS[1:3], perl=TRUE)
[1] "A\0J" "B\0P" "C\0J"
> sub('^','v_', LETTERS[1:3], perl=TRUE)
[1] "A\0\0" "B\0\0" "C\0m"
>
i.e., the result is random nonsense.
Note that this happens both for R-patched (2.0.1) and R-devel (2.1.0 alpha).
==> "forwarded" as bug report to R-bugs
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