help.search               package:base               R Documentation

Search the Help System

Description:

     Allows for searching the help system for documentation matching a
     given regular expression in the (file) name, alias, title, or
     keyword entries (or any combination thereof).  Topics and titles
     of the matched help entries are nicely displayed.

Usage:

     help.search(pattern, fields = c("alias", "title"),
                 apropos, keyword, whatis, ignore.case = TRUE,
                 package = NULL, lib.loc = NULL,
                 help.db = getOption("help.db"),
                 verbose = getOption("verbose"),
                 rebuild = FALSE)

Arguments:

 pattern: a character string containing a regular expression to be
          matched in the specified fields.  If this is given, the
          arguments `apropos', `keyword', and `whatis' are ignored.

  fields: a character vector specifying the fields of the help data
          bases to be searched.  The entries must be abbreviations of
          `"name"', `"alias"', `"title"', and `"keyword"',
          corresponding to the help page's (file) name, the topics it
          provides documentation for, its title, and the keywords it
          can be classified to.

 apropos: a character string containing a regular expression to be
          matched in the help page topics and title.

 keyword: a character string containing a regular expression to be
          matched in the help page keywords.

  whatis: a character string containing a regular expression to be
          matched in the help page topics.

ignore.case: a logical.  If `TRUE', case is ignored during matching; if
          `FALSE', pattern matching is case sensitive.

 package: a character vector with the names of packages to search
          through, or `NULL' in which case all available packages in
          the specified library trees `lib.loc' are searched.

 lib.loc: a character vector describing the location of R library trees
          to search through, or `NULL'.  The default value of `NULL'
          corresponds to all libraries currently known.

 help.db: a character string giving the file path to a previously built
          and saved help data base, or `NULL'.

 verbose: logical; if `TRUE', the search process is traced.

 rebuild: a logical indicating whether the help data base should be
          rebuilt.

Details:

     Upon installation of a package, the Perl script `Rd2contents.pl'
     creates a `CONTENTS' data base which contains the information on
     name, aliases, title and keywords (as well as the URL of the HTML
     version of the help file) in Debian Control Format.  This is the
     data base searched by `help.search()'.

     The arguments `apropos' and `whatis' play a role similar to the
     Unix commands with the same names.

     If possible, the help data base is saved to the file `help.db' in
     the `.R' subdirectory of the user's home directory or the current
     working directory.

     Note that currently, the aliases in the matching help files are
     not displayed.

Value:

     The results are returned in an object of class `"hsearch"', which
     has a print method for nicely displaying the results of the query.
     This mechanism is experimental, and may change in future versions
     of R.

See Also:

     `help'; `help.start' for starting the hypertext (currently HTML)
     version of R's online documentation, which offers a similar search
     mechanism.

     `apropos' uses regexps and has nice examples.

Examples:

     help.search("linear models")    # In case you forgot how to fit linear
                                     # models

     help.search("print")            # All help pages with topics or title
                                     # matching `print'
     help.search(apropos = "print")  # The same

     help.search(keyword = "hplot")  # All help pages documenting high-level
                                     # plots.

     ## Help pages with documented topics starting with `try'.
     help.search("\\btry", fields = "alias")
     ## Do not use `^' or `$' when matching aliases or keywords.

