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% File src/library/tools/man/Rdiff.Rd
% Part of the R package, https://www.R-project.org
% Copyright 2010-2022 R Core Team
% Distributed under GPL 2 or later

\name{Rdiff}
\alias{Rdiff}
\title{Difference R Output Files}
\description{
  Given two \R output files, compute differences ignoring headers,
  footers and some other differences.
}
\usage{
Rdiff(from, to, useDiff = FALSE, forEx = FALSE,
      nullPointers = TRUE, Log = FALSE)
}
\arguments{
  \item{from, to}{filepaths to be compared}
  \item{useDiff}{should \command{diff} be used to compare results?
    Overidden to false if the command is not available.}
  \item{forEx}{logical: extra pruning for \file{-Ex.Rout} files to
    exclude the header.}
  \item{nullPointers}{logical: should the displayed addresses of
    pointers be set to \code{0x00000000} before comparison?}
  \item{Log}{logical: should the returned value include a log of
    differences found?}
}
\details{
  
  The \R startup banner and any timing information from \command{R CMD
    BATCH} are removed from both files, together with lines about
  loading packages.  UTF-8 fancy quotes (see \code{\link{sQuote}}) and
  on Windows, Windows' so-called \sQuote{smart quotes}, are mapped to
  a simple quote.  Addresses of environments, compiled bytecode and
  other exotic types expressed as hex addresses
  (e.g., \code{<environment: 0x12345678>}) are mapped to
  \code{0x00000000}.  The files are then compared line-by-line.  If
  there are the same number of lines and \code{useDiff} is false, a
  simple \command{diff -b} -like display of differences is printed
  (which ignores trailing spaces and differences in numbers of
  consecutive spaces), otherwise \command{diff -bw} is called on the
  edited files.  (This tries to ignore all differences in whitespace:
  note that flag \option{-w} is not required by POSIX but is supported
  by GNU, Solaris and FreeBSD versions -- macOS uses an old GNU version.)

  This can compare uncompressed PDF files, ignoring differences in
  creation and modification dates.  However, non-ASCII text may not be
  handled in UTF-8 locales, and it does not check if the PDF files really
  are uncompressed.  This is unlikely to be supported in future versions
  of \R.

  Mainly for use in examples and tests, text from marker
  \samp{> ## IGNORE_RDIFF_BEGIN} up to (but not including)
  \samp{> ## IGNORE_RDIFF_END} is ignored.
}
\value{
  If \code{Log} is true, a list with components \code{status} (see
  below) and \code{out}, a character vector of descriptions of
  differences, possibly of zero length.

  Otherwise, a status indicator (invisibly), \code{0L} if and only if no
  differences were found.
}

\seealso{
  The shell script run as \command{R CMD Rdiff}, which uses
  \code{useDiff = TRUE}.
}

\keyword{utilities}