utility - Helper for find_in_files()

Internal helper used by find_in_files() to search text that is already in memory, such as the output of readLines().

Usage

grep_lines(
  pattern,
  x,
  ignore.case = TRUE,
  ignorecomments = FALSE,
  value = TRUE
)

Arguments

pattern

regular expression to look for

x

character vector to search, typically one element per line

ignore.case

logical passed to grepl()

ignorecomments

if TRUE, lines beginning with # are excluded

value

if TRUE, return matching lines; otherwise return a logical vector

Value

Character vector of matching lines if value = TRUE, otherwise a logical vector the same length as x. Returned values are named with line numbers where applicable.

Details

Search an in-memory character vector line by line

This is somewhat like grepv() but with these options: option to return numbers of the elements or line numbers as names of the output vector option to ignore commented-out lines of code (if searching with in lines of code) option to return just the matching part of the element or line instead of the whole line if desired.

use grepl to find all members of character vector z where the character string "h" appears in the string but the string does not start with zero or more spaces followed by the character "#"

See also

find_in_files() grepn() grepns() grepls()

Examples

EJAM:::grep_lines("x",  c("x", "y", "has any x x xxxxx"))

xx = c("   ej", "ej", "#ej", "   #ej", "asdf#ej",
  "   asdf#ej", "#   ej", "#   xej", "x#  ej", "  x#ej")

 cbind(xx, EJAM:::grep_lines("ej", xx, ignorecomments = TRUE,  value = FALSE))
 cbind(xx, EJAM:::grep_lines("ej", xx, ignorecomments = FALSE, value = FALSE))

 cbind(  EJAM:::grep_lines("ej", xx, ignorecomments = TRUE,    value = TRUE))
 cbind(  EJAM:::grep_lines("ej", xx, ignorecomments = FALSE,   value = TRUE))