R Utilities: Vector Based Versions of grep

These functions slightly extend the usage of grep but it is extended to a vector argument.

grep.vec(pattern.vec, x, operator="AND", ...)

grepvec( pattern.vec, x, operator="AND", value=FALSE, ...)

grep_leading( pattern, x, value=FALSE )

grepvec_leading( patternvec, x, value=FALSE )

Arguments

pattern.vec: String which should be looked for in vector x
x: A character vector
operator: An optional string. The default argument "AND" searches all entries in x which contain all elements of pattern.vec. If operator is different from the default, then the "OR" logic applies, i.e. the functions searches for vector entries which contain at least one of the strings in pattern.vec.
pattern: String
patternvec: Vector of strings
value: Logical indicating whether indices or values are requested
...: Arguments to be passed to base::grep (e.g., fixed=TRUE)

Examples

#############################################################################
# EXAMPLE 1: Toy example
#############################################################################

vec <- c("abcd", "bcde", "aedf", "cdf" )
# search for entries in vec with contain 'a' and 'f'
#  -> operator="AND"
grep.vec( pattern.vec=c("a","f"), x=vec )
  ##   $x
  ##   [1] "aedf"
  ##   $index.x
  ##   [1] 3

grepvec( pattern.vec=c("a","f"), x=vec, value=TRUE)
grepvec( pattern.vec=c("a","f"), x=vec, value=FALSE)

# search for entries in vec which contain 'a' or 'f'
grep.vec( pattern.vec=c("a","f"), x=vec, operator="OR")
  ##   $x
  ##   [1] "abcd" "aedf" "cdf"
  ##   $index.x
  ##   [1] 1 3 4