Hi Martin,
I assume you want to check whether a particular character string
contains a digit. In this case you should use the following pattern:
"[[:digit:]]" instead of "[:digit:]".
From ?regex:
"A character class is a list of characters enclosed between [ and ]
which matches any single character in that list; unless the first
character of the list is the caret ^, when it matches any character not
in the list. ... Certain named classes of characters are predefined...
For example, [[:alnum:]] means [0-9A-Za-z]"
So if you use simply "[:digit:]" as a pattern, it means: a character
string which contains any of the following characters: ':', 'd', 'i',
'g', 't'. Your second test case contains 'd', whereas the first case
contains neither of the above characters.
HTH,
Denes
On 07/02/2018 02:52 PM, Martin Møller Skarbiniks Pedersen wrote:
Hi,
Have I found a bug in R? Or misunderstood something about grep() ?
Case 1 gives the expected output
Case 2 does not gives the expected output.
I expected integer(0) also for this case.
case 1:
grep("[:digit:]", "**ABAAbabaabackabaloneaban")
integer(0)
case 2:
grep("[:digit:]", "**ABAAbabaabackabaloneaband")
[1] 1
Regards
Martin
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