Pattern matching on data frame rows

greprows() searches for pattern matches within a data frames columns and returns the related rows or row indices.

grepvrows() is identical to greprows() except with the default value = TRUE.

greplrows() returns a logical vector (match or not for each row of dat).

Usage

greprows(
  dat,
  pattern,
  cols = NULL,
  value = FALSE,
  ignore.case = FALSE,
  perl = FALSE,
  fixed = FALSE,
  invert = FALSE
)

greplrows(
  dat,
  pattern,
  cols = NULL,
  ignore.case = FALSE,
  perl = FALSE,
  fixed = FALSE,
  invert = FALSE
)

grepvrows(
  dat,
  pattern,
  cols = NULL,
  value = TRUE,
  ignore.case = FALSE,
  perl = FALSE,
  fixed = FALSE,
  invert = FALSE
)

Arguments

dat

Data frame

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.

cols

[character]

Character vector of columns to search.

If NULL (default) all character and factor columns will be searched.

value

[logical]

Should a data frame of rows be returned.

If FALSE (defauly) row indices will be returned instead of the rows themselves.

ignore.case

if FALSE, the pattern matching is case sensitive and if TRUE, case is ignored during matching.

perl

logical. Should Perl-compatible regexps be used?

fixed

logical. If TRUE, pattern is a string to be matched as is. Overrides all conflicting arguments.

invert

logical. If TRUE return indices or values for elements that do not match.

Value

A data frame of the corresponding rows or, if value = FALSE, the corresponding row numbers.

See also

grep()

Examples

dat <- data.frame(
    first = letters,
    second = factor(rev(LETTERS)),
    third = "Q"
)
greprows(dat, "A|b")
#> [1]  2 26
greprows(dat, "A|b", ignore.case = TRUE)
#> [1]  1  2 25 26
greprows(dat, "c", value = FALSE)
#> [1] 3