\HeaderA{abbreviate}{Abbreviate Strings}{abbreviate}
\keyword{character}{abbreviate}
\begin{Description}\relax
Abbreviate strings to at least \code{minlength} characters,
such that they remain \emph{unique} (if they were).
\end{Description}
\begin{Usage}
\begin{verbatim}
abbreviate(names.arg, minlength = 4, use.classes = TRUE,
           dot = FALSE)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{names.arg}] a vector of names to be abbreviated.
\item[\code{minlength}] the minimum length of the abbreviations.
\item[\code{use.classes}] logical (currently ignored by \R).
\item[\code{dot}] logical; should a dot (\code{"."}) be appended?
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The algorithm used is similar to that of S.
First spaces at the beginning of the word are stripped.
Then any other spaces are stripped.
Next lower case vowels are removed followed by lower case consonants.
Finally if the abbreviation is still longer than \code{minlength}
upper case letters are stripped.

Letters are always stripped from the end of the word first.
If an element of \code{names.arg} contains more than one word (words
are separated by space) then at least one letter from each word will be
retained.
If a single string is passed it is abbreviated in the same manner as a
vector of strings.

Missing (\code{NA}) values are not abbreviated.

If \code{use.classes} is \code{FALSE} then the only distinction is to
be between letters and space.  This has NOT been implemented.
\end{Details}
\begin{Value}
A character vector containing abbreviations for the strings in its
first argument.  Duplicates in the original \code{names.arg} will be
given identical abbreviations.  If any non-duplicated elements have
the same \code{minlength} abbreviations then \code{minlength} is
incremented by one and new abbreviations are found for those elements
only.  This process is repeated until all unique elements of
\code{names.arg} have unique abbreviations.

The character version of \code{names.arg} is attached to the returned
value as a names argument.
\end{Value}
\begin{Section}{Warning}
This is really only suitable for English, and does not work correctly with
non-ASCII characters in UTF-8 locales.  It will warns if used with
non-ASCII characters.
\end{Section}
\begin{SeeAlso}\relax
\code{\LinkA{substr}{substr}}.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
x <- c("abcd", "efgh", "abce")
abbreviate(x, 2)

(st.abb <- abbreviate(state.name, 2))
table(nchar(st.abb))# out of 50, 3 need 4 letters
\end{ExampleCode}
\end{Examples}

