character-utils: Some utility functions to operate on strings

In Bioconductor/S4Vectors: Foundation of vector-like and list-like containers in Bioconductor

Some utility functions to operate on strings

Description

Some low-level string utilities to operate on ordinary character vectors. For more advanced string manipulations, see the Biostrings package.

Usage

unstrsplit(x, sep="")

## more to come...

Arguments

x	A list-like object where each list element is a character vector, or a character vector (identity).
sep	A single string containing the separator.

Details

unstrsplit(x, sep) is equivalent to (but much faster than) sapply(x, paste0, collapse=sep). It performs the reverse transformation of strsplit( , fixed=TRUE), that is, if x is a character vector with no NAs and sep a single string, then unstrsplit(strsplit(x, split=sep, fixed=TRUE), sep) is identical to x. A notable exception to this though is when strsplit finds a match at the end of a string, in which case the last element of the output (which should normally be an empty string) is not returned (see ?strsplit for the details).

Value

A character vector with one string per list element in x.

Author(s)

Hervé Pagès

See Also

• The strsplit function in the base package.

Examples

x <- list(A=c("abc", "XY"), B=NULL, C=letters[1:4])
unstrsplit(x)
unstrsplit(x, sep=",")
unstrsplit(x, sep=" => ")

data(islands)
x <- names(islands)
y <- strsplit(x, split=" ", fixed=TRUE)
x2 <- unstrsplit(y, sep=" ")
stopifnot(identical(x, x2))

## But...
names(x) <- x
y <- strsplit(x, split="in", fixed=TRUE)
x2 <- unstrsplit(y, sep="in")
y[x != x2]
## In other words: strsplit() behavior sucks :-/

Bioconductor/S4Vectors documentation built on Nov. 17, 2024, 6:55 p.m.