R: Change Wildcard or Globbing Pattern into Regular Expression

glob2rx {utils} | R Documentation

## Change Wildcard or Globbing Pattern into Regular Expression

### Description

Change wildcard aka globbing patterns into the corresponding regular expressions (`regexp`).

### Usage

    glob2rx(pattern, trim.head = FALSE, trim.tail = TRUE)

### Arguments

`pattern` | character vector
`trim.head` | logical specifying if leading `"^.*"` should be trimmed from the result.
`trim.tail` | logical specifying if trailing `".*$"` should be trimmed from the result.

### Details

This takes a wildcard as used by most shells and returns an equivalent regular expression. `?` is mapped to `.` (match a single character), `*` to `.*` (match any string, including an empty one), and the pattern is anchored (it must start at the beginning and end at the end). Optionally, the resulting regexp is simplified.

Note that now even `(`, `[` and `{` can be used in `pattern`, but `glob2rx()` may not work correctly with arbitrary characters in `pattern`.

### Value

A character vector of the same length as the input `pattern` where each wildcard is translated to the corresponding regular expression.

### Author(s)

Martin Maechler, Unix/sed based version, 1991; current: 2004

### See Also

`regexp` about regular expression, `sub`, etc about substitutions using regexps.

### Examples

    stopifnot(glob2rx("abc.*") == "^abc\\.",
              glob2rx("a?b.*") == "^a.b\\.",
              glob2rx("a?b.*", trim.tail = FALSE) == "^a.b\\..*$",
              glob2rx("*.doc") == "^.*\\.doc$",
              glob2rx("*.doc", trim.head = TRUE) == "\\.doc$",
              glob2rx("*.t*")  == "^.*\\.t",
              glob2rx("*.t??") == "^.*\\.t..$",
              glob2rx("*[*")  == "^.*\\["
    )

[Package utils version 3.1.2 Index]