Help Search Utilities

Description

Utilities for searching the help system.

Usage

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hsearch_db(package = NULL, lib.loc = NULL,
           types = getOption("help.search.types"), 
           verbose = getOption("verbose"),
           rebuild = FALSE, use_UTF8 = FALSE)
hsearch_db_concepts(db = hsearch_db())
hsearch_db_keywords(db = hsearch_db())

Arguments

package

a character vector with the names of packages to search through, or NULL in which case all available packages in the library trees specified by 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.

types

a character vector listing the types of documentation to search. See help.search for details.

verbose

a logical controlling the verbosity of building the help search database. See help.search for details.

rebuild

a logical indicating whether the help search database should be rebuilt. See help.search for details.

use_UTF8

logical: should results be given in UTF-8 encoding?

db

a help search database as obtained by calls to hsearch_db().

Details

hsearch_db() builds and caches the help search database for subsequent use by help.search. (In fact, re-builds only when forced (rebuild = TRUE) or “necessary”.)

The format of the help search database is still experimental, and may change in future versions. Currently, it consists of four tables: one with base information about all documentation objects found, including their names and titles and unique ids; three more tables contain the individual aliases, concepts and keywords together with the ids of the documentation objects they belong to. Separating out the latter three tables accounts for the fact that a single documentation object may provide several of these entries, and allows for efficient searching.

See the details in help.search for how searchable entries are interpreted according to help type.

hsearch_db_concepts() and hsearch_db_keywords() extract all concepts or keywords, respectively, from a help search database, and return these in a data frame together with their total frequencies and the numbers of packages they are used in, with entries sorted in decreasing total frequency.

Examples

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db <- hsearch_db()
## Total numbers of documentation objects, aliases, keywords and
## concepts (using the current format):
sapply(db, NROW)
## Can also be obtained from print method:
db
## 10 most frequent concepts:
head(hsearch_db_concepts(), 10)
## 10 most frequent keywords:
head(hsearch_db_keywords(), 10)

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