abbreviate

R Base 3.6.2

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

Syntax

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

Arguments

Parameter	Description
`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: should lowercase characters be removed first?
`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 character string specifying the method used with default "left.kept", see ‘Details’ below. Partial matches allowed.
`named`	logical: should names (with original vector) be returned.

Return Value

A character vector containing abbreviations for the character 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

Details

The default algorithm (method = "left.kept") used is similar to that of S. For a single string it works as follows. First spaces at the ends of the string are stripped. Then (if necessary) any other spaces are stripped. Next, lower case vowels are removed followed by lower case consonants. Finally if the abbreviation is still longer than minlength upper case letters and symbols are stripped. Characters are always stripped from the end of the strings first. If an element of names.arg contains more than one word (words are separated by spaces) 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.

Examples

Example

# NOT RUN {
x <- c("abcd", "efgh", "abce")
abbreviate(x, 2)
abbreviate(x, 2, strict = TRUE) # >> 1st and 3rd are == "ab"

(st.abb <- abbreviate(state.name, 2))
stopifnot(identical(unname(st.abb),
           abbreviate(state.name, 2, named=FALSE)))
table(nchar(st.abb)) # out of 50, 3 need 4 letters :
as <- abbreviate(state.name, 3, strict = TRUE)
as[which(as == "Mss")]
# }
# NOT RUN {
## and without distinguishing vowels:
st.abb2 <- abbreviate(state.name, 2, FALSE)
cbind(st.abb, st.abb2)[st.abb2 != st.abb, ]

## 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)
# }