a data.frame. Default is data(XenaData).
The input of this option can only be data(XenaData) or its subset.
pattern
character string containing a regular expression
(or character string for fixed = TRUE) to be matched
in the given character vector. Coerced by
as.character to a character string if possible. If a
character vector of length 2 or more is supplied, the first element
is used with a warning. Missing values are allowed except for
regexpr, gregexpr and regexec.
ignore.case
if FALSE, the pattern matching is case
sensitive and if TRUE, case is ignored during matching.