R: Text before or after nth occurrence of pattern.

str_after_nth {filesstrings}

R Documentation

Text before or after nth occurrence of pattern.

Description

Extract the part of a string which is before or after the nth occurrence of a specified pattern, vectorized over the string. n can be negatively indexed. See 'Arguments'.

Usage

str_after_nth(strings, pattern, n)

str_after_first(strings, pattern)

str_after_last(strings, pattern)

str_before_nth(strings, pattern, n)

str_before_first(strings, pattern)

str_before_last(strings, pattern)

Arguments

`strings`	A character vector.
`pattern`	A character vector. Pattern(s) specified like the pattern(s) in the stringr package (e.g. look at `stringr::str_locate()`). If this has length >1 its length must be the same as that of `string`.
`n`	A natural number to identify the nth occurrence (defaults to first (`n = 1`)). This can be negatively indexed, so if you wish to select the last occurrence, you need `n = -1`, for the second-last, you need `n = -2` and so on.

Details

str_after_first(...) is just str_after_nth(..., n = 1).
str_after_last(...) is just str_after_nth(..., n = -1).
str_before_first(...) is just str_before_nth(..., n = 1).
str_before_last(...) is just str_before_nth(..., n = -1).

Value

A character vector of the desired strings.

Examples

string <- "ab..cd..de..fg..h"
str_after_nth(string, "\\.\\.", 3)
str_before_nth(string, "e", 1)
str_before_nth(string, "\\.", -3)
str_before_nth(string, ".", -3)
str_before_nth(rep(string, 2), fixed("."), -3)

[Package filesstrings version 2.5.0 Index]