Build and Query R or Package News Information

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Description

Build and query the news data base for R or add-on packages.

Usage

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news(query, package = "R", lib.loc = NULL, format = NULL,
     reader = NULL, db = NULL)

## S3 method for class 'news_db'
print(x, doBrowse = interactive(),
      browser = getOption("browser"), ...)

Arguments

query

an expression for selecting news entries

package

a character string giving the name of an installed add-on package, or "R".

lib.loc

a character vector of directory names of R libraries, or NULL. The default value of NULL corresponds to all libraries currently known.

format

Not yet used.

reader

Not yet used.

db, x

a news db obtained from news().

doBrowse

logical specifying that the news should be opened in the browser (by browseURL, accessible as via help.start) instead of printed to the console.

browser

the browser to be used, see browseURL.

...

potentially further arguments passed to print().

Details

If package is "R" (default), a news db is built with the news since the 3.0.0 release of R (corresponding to R's top-level ‘NEWS’ file). Otherwise, if the given add-on package can be found in the given libraries, it is attempted to read its news in structured form from files ‘inst/NEWS.Rd’, ‘NEWS’ or ‘inst/NEWS’ (in that order).

File ‘inst/NEWS.Rd’ should be an Rd file given the entries as Rd \itemize lists, grouped according to version using section elements with names starting with a suitable prefix (e.g. “Changes in version” followed by a space and the version number, and optionally followed by a space and a parenthesized ISO 8601 (%Y-%m-%d, see strptime) format date, and possibly further grouped according to categories using \subsection elements named as the categories. At the very end of \section{..}, the date may also be specified as (%Y-%m-%d, <note>), i.e., including parentheses.

The plain text ‘NEWS’ files in add-on packages use a variety of different formats; the default news reader should be capable to extract individual news entries from a majority of packages from the standard repositories, which use (slight variations of) the following format:

  • Entries are grouped according to version, with version header “Changes in version” at the beginning of a line, followed by a version number, optionally followed by an ISO 8601 format date, possibly parenthesized.

  • Entries may be grouped according to category, with a category header (different from a version header) starting at the beginning of a line.

  • Entries are written as itemize-type lists, using one of o, *, - or + as item tag. Entries must be indented, and ideally use a common indentation for the item texts.

Additional formats and readers may be supported in the future.

Package tools provides an (internal) utility function news2Rd to convert plain text ‘NEWS’ files to Rd. For ‘NEWS’ files in a format which can successfully be handled by the default reader, package maintainers can use tools:::news2Rd(dir, "NEWS.Rd"), possibly with additional argument codify = TRUE, with dir a character string specifying the path to a package's root directory. Upon success, the ‘NEWS.Rd’ file can further be improved and then be moved to the ‘inst’ subdirectory of the package source directory.

The news db built is a character data frame inheriting from "news_db" with variables Version, Category, Date and Text, where the last contains the entry texts read, and the other variables may be NA if they were missing or could not be determined.

Using query, one can select news entries from the db. If missing or NULL, the complete db is returned. Otherwise, query should be an expression involving (a subset of) the variables Version, Category, Date and Text, and when evaluated within the db returning a logical vector with length the number of entries in the db. The entries for which evaluation gave TRUE are selected. When evaluating, Version and Date are coerced to numeric_version and Date objects, respectively, so that the comparison operators for these classes can be employed.

Value

A data frame inheriting from class "news_db", with attributes "package" (and "subset" if the query lead to proper subsetting).

Examples

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## Build a db of all R news entries.
db <- news()

## Bug fixes with PR number in 3.0.1.
db3 <- news(Version == "3.0.1" & grepl("^BUG", Category) & grepl("PR#", Text),
            db = db)


## News from a date range ('Matrix' is there in a regular R installation):
if(length(iM <- find.package("Matrix", quiet=TRUE)) && nzchar(iM)) {
   dM <- news(package="Matrix")
   stopifnot(identical(dM, news(db=dM)))
   dM2014 <- news("2014-01-01" <= Date & Date <= "2014-12-31", db = dM)
   stopifnot(paste0("1.1-", 2:4) %in% dM2014[,"Version"])
}

## Which categories have been in use? % R-core maybe should standardize a bit more
sort(table(db[, "Category"]), decreasing = TRUE)
## Entries with version >= 3.0.0 (including "3.0.0 patched"):
table(news(Version >= "3.0.0", db = db)$Version)

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