R: Abbreviate Strings

abbreviate {base} | R Documentation

## Abbreviate Strings

### Description

Abbreviate strings to at least `minlength` characters, such that they remain unique (if they were), unless `strict=TRUE`.

### Usage

    abbreviate(names.arg, minlength = 4, use.classes = TRUE,
               dot = FALSE, strict = FALSE,
               method = c("left.kept", "both.sides"))

### Arguments

`names.arg` | a character vector of names to be abbreviated, or an object to be coerced to a character vector by `as.character`.
`minlength` | the minimum length of the abbreviations.
`use.classes` | logical (currently ignored by R).
`dot` | logical: should a dot (`"."`) be appended?
`strict` | logical: should `minlength` be observed strictly? Note that setting `strict=TRUE` may return non-unique strings.
`method` | a string specifying the method used with default `"left.kept"`, see ‘Details’ below.

### Details

The algorithm (`method = "left.kept"`) used is similar to that of S. For a single string it works as follows. First all spaces at the beginning of the string are stripped. Then (if necessary) any other spaces are stripped. Next, lower case vowels are removed (starting at the right) followed by lower case consonants. Finally if the abbreviation is still longer than `minlength` upper case letters are stripped.

Characters are always stripped from the end of the word first. If an element of `names.arg` contains more than one word (words are separated by space) then at least one letter from each word will be retained.

Missing (`NA`) values are unaltered.

If `use.classes` is `FALSE` then the only distinction is to be between letters and space. This has NOT been implemented.

### Value

A character vector containing abbreviations for the strings in its first argument. Duplicates in the original `names.arg` will be given identical abbreviations. If any non-duplicated elements have the same `minlength` abbreviations then, if `method = "both.sides"` the basic internal `abbreviate()` algorithm is applied to the characterwise reversed strings; if there are still duplicated abbreviations and if `strict=FALSE` as by default, `minlength` is incremented by one and new abbreviations are found for those elements only. This process is repeated until all unique elements of `names.arg` have unique abbreviations.

The character version of `names.arg` is attached to the returned value as a names argument: no other attributes are retained.

### Warning

This is really only suitable for English, and does not work correctly with non-ASCII characters in multibyte locales. It will warn if used with non-ASCII characters.

### See Also

`substr`.

### Examples

    x <- c("abcd", "efgh", "abce")
    abbreviate(x, 2)
    abbreviate(x, 2, strict=TRUE)# >> 1st and 3rd are == "ab"

    (st.abb <- abbreviate(state.name, 2))
    table(nchar(st.abb))# out of 50, 3 need 4 letters :
    as <- abbreviate(state.name, 3, strict=TRUE)
    as[which(as == "Mss")]

    ## method="both.sides" helps:  no 4-letters, and only 4 3-letters:
    st.ab2 <- abbreviate(state.name, 2, method="both")
    table(nchar(st.ab2))
    ## Compare the two methods:
    cbind(st.abb, st.ab2)

[Package base version 2.15.1 Index]