valuetype: pattern matching using valuetype
Description
Pattern matching in quanteda using the valuetype argument.Arguments
valuetype
how to interpret keyword expressions: "glob" for
"glob"-style wildcard expressions; "regex" for regular expressions;
or "fixed" for exact matching. See valuetype for details. Details
Pattern matching in in quanteda uses "glob"-style pattern
matching as the default, because this is simpler than regular expression
matching while addressing most users' needs. It is also has the advantage
of being identical to fixed pattern matching when the wildcard characters
(`*` and `?`) are not used. Finally, most dictionary formats use
glob matching.
"glob"- "glob"-style wildcard expressions, the quanteda default.
The implementation used in quanteda uses `*` to match any number of any
characters including none, and `?` to match any single character. See also
glob2rx and References below.
"regex"- Regular expression matching.
"fixed"- Fixed (literal) pattern matching.