lcSuffix: Compute the longest common prefix or suffix of a string

Description

These functions find the longest common prefix or suffix among the strings in a character vector.

Usage

lcPrefix(x, ignore.case=FALSE)
lcPrefixC(x, ignore.case=FALSE)
lcSuffix(x, ignore.case=FALSE)

Arguments

a character vector.

ignore.case

A logical value indicating whether or not to ignore the case in making comparisons.

Value

The common prefix or suffix.

Details

Computing the longest common suffix is helpful for truncating names of objects, like microarrays, that often have a common suffix, such as .CEL.

There are some potential problems with the approach used if multibyte character encodings are being used.

lcPrefixC is a faster implementation in C. It only handles ascii characters.

Examples

Run this code

s1 <- c("ABC.CEL", "DEF.CEL")
lcSuffix(s1)

s2 <- c("ABC.123", "ABC.456")
lcPrefix(s2)


CHK <- stopifnot

CHK(".CEL" == lcSuffix(s1))
CHK("bc" == lcSuffix(c("abc", "333abc", "bc")))
CHK("c" == lcSuffix(c("c", "abc", "xxxc")))
CHK("" == lcSuffix(c("c", "abc", "xxx")))

CHK("ABC." == lcPrefix(s2))
CHK("ab" == lcPrefix(c("abcd", "abcd123", "ab", "abc", "abc333333")))
CHK("a" == lcPrefix(c("abcd", "abcd123", "ax")))
CHK("a" == lcPrefix(c("a", "abcd123", "ax")))
CHK("" == lcPrefix(c("a", "abc", "xxx")))

CHK("ab" == lcPrefixC(c("abcd", "abcd123", "ab", "abc", "abc333333")))
CHK("a" == lcPrefixC(c("abcd", "abcd123", "ax")))
CHK("a" == lcPrefixC(c("a", "abcd123", "ax")))
CHK("" == lcPrefixC(c("a", "abc", "xxx")))