Piecewise pattern matching and replacement

psub calls gsub for each pattern / replacement pair. Where a pattern is not found, a warning is issued and nothing is replaced for that pattern / replacement pair. Unlike gsub, the first argument is the vector where matches are sought, meaning that it can be easily used in a pipeline.

Usage

psub(x, pattern, replacement, exact = TRUE, ...)

Arguments

x: A character vector.
pattern: A vector of patterns to replace.
replacement: A character vector of the same length as pattern with the corresponding replacements.
exact: A logical to denote whether pattern is to be an exact match (the default). When FALSE, pattern is treated as a regular expression.
...: Other arguments to gsub.

Value

A character vector of the same length as x with matched patterns replaced.

Details

The default behaviour is to look for an exact match of pattern. This means that only those elements in x that fully match pattern are replaced. See examples for how this works in practice.

Examples

# Capitalise some letters
psub(letters[1:7], c("a", "c", "e"), c("A", "C", "E"))
#> [1] "A" "b" "C" "d" "E" "f" "g"

# By default exact matches are sought
psub("ace", c("a", "c", "e"), c("A", "C", "E"))
#> Warning: "a" not found in `x`.
#> Warning: "c" not found in `x`.
#> Warning: "e" not found in `x`.
#> [1] "ace"

# Use exact = FALSE to replace a regular expression
psub("ace", c("a", "c", "e"), c("A", "C", "E"), exact = FALSE)
#> [1] "ACE"

# Replace selected values in a vector
psub(c("one", "two", "three"), c("one", "three"), c("ONE", "THREE"))
#> [1] "ONE"   "two"   "THREE"