R for Windows FAQ
Frequently Asked Questions on R for Windows
Version for rw1063
Brian Ripley
Table of Contents
*****************
1 Introduction
2 Installation and Usage
2.1 Where can I find the latest version?
2.2 How do I install R for Windows?
2.3 How do I run it?
2.4 How do I UNinstall R?
2.5 What's the best way to upgrade?
2.6 There seems to be a limit on the memory it uses!
2.7 How can I keep workspaces for different projects in different directories?
2.8 How do I print from R?
2.9 Can I use `R BATCH'?
2.10 Can I use rw1063 with ESS and (X)emacs?
2.11 What are HOME and working directories?
2.12 How do I set environment variables?
2.13 R can't find my file, but I know it is there!
2.14 Does R use the Registry?
2.15 Entering certain characters crashes Rgui.
2.16 The internet download functions fail.
2.17 Other strange crashes.
3 Packages
3.1 Can I install packages (libraries) in this version?
3.2 I don't have permission to write to the `rw1063\library' directory.
3.3 The packages I installed do not appear in the HTML help system.
3.4 My functions are not found by the HTML help search system.
3.5 Loading a package fails.
3.6 Package TclTk does not work.
3.7 Hyperlinks in Compiled HTML sometimes do not work.
3.8 `update.packages()' fails
4 Windows Features
4.1 What should I expect to behave differently from the Unix version of R?
4.2 I hear about some nifty features: please tell me about them!
4.3 Circles appear as ovals on screen
4.4 How do I move focus to a graphics window or the console?
5 Workspaces
5.1 My workspace gets saved in a strange place: how do I stop this?
5.2 How do I store my workspace in a different place?
5.3 Can I load workspaces saved under Unix/GNU-Linux?
6 The R Console and Fonts
6.1 I would like to be able to use Japanese fonts
6.2 I don't see characters with accents at the R console, for example in ?text.
6.3 When using Rgui the output to the console seems to be delayed.
6.4 Long lines in the console or pager are truncated.
7 Building from Source
7.1 How can I compile R from source?
7.2 Can I use a fast BLAS?
7.3 How do I include compiled C code?
7.4 How do I debug code that I have compiled and dyn.load-ed?
7.5 How do I include C++ code?
7.6 The output from my C code disappears. Why?
7.7 The output from my Fortran code disappears. Why?
7.8 The console freezes when my compiled code is running.
1 Introduction
**************
This FAQ is for the Windows port of R: it describes features specific to
that version. The main R FAQ can be found at
`http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html'.
The information here applies only to recent versions of R for Windows,
(`1.4.0' or later); the current version is often called something like
`rw1063' (although not officially).
2 Installation and Usage
************************
2.1 Where can I find the latest version?
========================================
Go to any CRAN site (see `http://cran.r-project.org/mirrors.html' for a
list), navigate to the `bin/windows/base' directory and collect the
files you need. There are two versions of the distribution.
1) `rw1063.exe' is about 19Mb and gives a complete installation.
2) Directory `miniR' contains `miniR.exe' and eight files
`miniR-?.bin'. You can put `miniR.exe' and `miniR-1.bin' on one floppy
and the remaining `miniR-?.bin' on a floppy each. This is a small
installation, containing the text and compiled HTML versions of the
help files and the _An Introduction to R_ and _Data Import/Export_
manuals in PDF.
2.2 How do I install R for Windows?
===================================
First, you need Windows 95/98/ME/NT4/2000/XP: Windows 3.11+win32s will
not work. Your file system must allow long file names (as is likely
except perhaps for some network-mounted systems).
If you want to build packages from sources, we recommend that you choose
an installation path not containing spaces. (Using a path with spaces
in will probably work, but is little-tested.)
To use `rw1063.exe' or `miniR.exe'. Just double-click on the icon and
follow the instructions. If you installed R this way you can uninstall
it from the Control Panel or Start Menu (unless you supressed making a
group for R).
Choose a working directory for R. If you installed manually, make a
shortcut to `rw1063\bin\Rgui.exe' on your desktop or somewhere on the
Start menu file tree. Right-click the shortcut, select Properties...
and change the `Start in' field to your working directory.
You may also want to add command-line arguments at the end of the Target
field, for example `--sdi --max-mem-size=40M'. You can also set
environment variables at the end of the Target field, for example
`R_LIBS=p:/myRlib'.
2.3 How do I run it?
====================
Just double-click on the shortcut you prepared at installation.
If you want to set up another project, make a new shortcut or use the
existing one and change the `Start in' field of the Properties.
You may if you prefer run R from the command line of any shell you use,
for example an `MS-DOS window' (Windows 9x/ME), a `Command Prompt'
(Windows 2000/XP) or a port of a Unix shell such as `tcsh' or `bash'.
(The command line can be anything you would put in the Target field of
a shortcut, and the starting directory will be the currect working
directory of the shell.)
2.4 How do I UNinstall R?
=========================
Normally you can do this from the R group on the Start Menu or from the
`Add/Remove Programs' in the Control Panel. If it does not appear
there or if you want to remove an old version, run `unins000.exe' in
the top-level installation directory. (As from version 1.6.2 there will
be a separate uninstall item in the R group for each installed version
of R.)
Uninstalling R only removes files from the initial installation, not for
example packages you have installed.
If all else fails, you can just delete the whole directory in which R
was installed.
2.5 What's the best way to upgrade?
===================================
That's a matter of taste. For most people the best thing to do is to
uninstall R (see the previous Q), install the new version, copy any
installed packages to the library folder in the new installation, run
`update.packages()' (from the menu, if you prefer) and then delete
anything left of the old installation. Different versions of R are
quite deliberately installed in parallel folders so you can keep old
versions around if you prefer.
2.6 There seems to be a limit on the memory it uses!
====================================================
Indeed there is. It is set by the command-line flag `--max-mem-size'
(*note How do I install R for Windows?::) and defaults to the smaller
of the amount of physical RAM in the machine and 1Gb. It can be set to
any amount over 10M. (R will not run in less.) Be aware though that
Windows has (in most versions) a maximum amount of user virtual memory
of 2Gb, and parts of this can be reserved by processes but not used.
Because of the way the memory manager works, it is possible that there
will be free memory but R will not be able to make use of it.
Use `?Memory' and `?memory.size' for information about memory usage.
The limit can be raised by calling `memory.limit' within a running R
session.
We have found that starting R with too large a value of
`--max-mem-size' may fail: the limit seemed to be about 1.7Gb on
Windows 2000 Professional.
R can be compiled to use a different memory manager which might be
better at using large amounts of memory, but is substantially slower
(making R several times slower on some tasks).
2.7 How can I keep workspaces for different projects in different directories?
==============================================================================
Create a separate shortcut for each project: see Q2.3. All the paths to
files used by R are relative to the starting directory, so setting the
`Start in' field automatically helps separate projects.
Alternatively, start R by double-clicking on a saved `.RData' file in
the directory for the project you want to use, or drag-and-drop a file
with extension `.RData' onto an R shortcut. In either case, the
working directory will be set to that containing the file.
2.8 How do I print from R?
==========================
It depends what you want to print.
* You can print the graphics window from its menu or by using
`dev.print' with suitable arguments (see its help page: most likely
`dev.print(win.graph)' will work).
* You can print from the R console or pager by `File | Print'.
(This will print the selection if there is one, otherwise the whole
console or pager contents.)
* You can print help files from the pager or HTML browser.
* If you have configured `RHOME\bin\helpPRINT.bat' and have LaTeX
installed you can print help files by `help(fn_name,
offline=TRUE)'.
2.9 Can I use `R BATCH'?
========================
Yes, if you have Perl and the files for making source packages (from
`rw1063.exe') installed. The Windows analogue is `Rcmd BATCH': use
`Rcmd BATCH --help' for full details.
Otherwise you can set up a batch file using `Rterm.exe'. A sample
batch file might contain (as one line)
path_to_R\bin\Rterm.exe --no-restore --no-save < %1 > %1.out
2.10 Can I use rw1063 with ESS and (X)emacs?
============================================
Yes. Recent versions of ESS (e.g. 5.1.20) come with support for this
version of R, and there is support for interrupting the R process from
ESS (by `C-c C-c').
For help with ESS, please send email to <ESS-help@stat.ethz.ch>, not
the R mailing lists.
2.11 What are HOME and working directories?
===========================================
Several places in the documentation use these terms.
The working directory is the directory from which `Rgui' or `Rterm' was
launched, unless a shortcut was used when it is given by the `Start in'
field of the shortcut's properties. You can find this from R code by
the call `getwd()'.
The home directory is set as follows:
If environment variable `R_USER' is set, its value is used.
Otherwise if environment variable `HOME' is set, its value is used.
Otherwise if environment variables `HOMEDRIVE' and `HOMEPATH' are set,
the value is `${HOMEDRIVE}${HOMEPATH}'.
If all of these fail, the current working directory is used.
You can find this from R code by `Sys.getenv("R_USER")'.
2.12 How do I set environment variables?
========================================
Environment variables can be set in R in three different ways.
1. On the command line as name=value pairs. For example in the
shortcut to `RGui' you could have
path_to_R\bin\Rgui.exe HOME=p:/ R_LIBS=p:/myRlib
2. In an environment file `.Renviron' in the working directory or
your home directory, for example containing the line
R_LIBS=p:/myRlib
See `?Startup' for more details of environment files.
3. For all applications via Windows. How you set an environment
variable is system specific: in Windows 9x you can set them in
`autoexec.bat' or in an MS-DOS window from which you launch `Rgui'
/ `Rterm'. Under Windows NT/2000/XP you can use the control panel
or the properties of `My Computer'. Under Windows ME you can use
the System Configuration Utility (under Programs, Accessories,
System Tools on the Start menu). You may have to log out or
reboot for such changes to take effect.
The order of precedence for environmental variables is the order in
which these options are listed, that is the command line then
`.Renviron' then the inherited environment.
2.13 R can't find my file, but I know it is there!
==================================================
How did you specify it? Backslashes have to be doubled in R character
strings, so for example one needs
`"d:\\rw1063\\library\\xgobi\\scripts\\xgobi.bat"'. Make life easier
for yourself by using forward slashes as path separators: they do work
under Windows.
Another possible source of grief is spaces in folder names. We have
tried to make R work on paths with spaces in, but lots of people writing
packages for Unix do not bother. So it is worth trying the alternative
short name (something like `PROGRA~1'; you can get it as the `MS-DOS
name' from the Properties of the file on most versions of Windows, and
from `dir /X' in a `Command Prompt' window on 2000/XP).
2.14 Does R use the Registry?
=============================
Not itself.
The installers set some entries to allow uninstallation. In addition
they set a Registry key `LOCAL_MACHINE\Software\R-core\R' giving the
version and install path. Again, this is not used by R itself, but it
will be used by the DCOM interface
(`http://cran.r-project.org/other-software.html'). Finally, a file
association for extension `.RData' is set in the Registry.
You can add the Registry entries by running `RSetReg.exe' in the `bin'
folder, and remove them by running this with argument `/U'. Note that
the settings are all per machine and not per user, and that this
neither sets up nor removes the file associations.
2.15 Entering certain characters crashes Rgui.
==============================================
This used to happen occasionally, and all the occurrences we have
solved have been traced to faulty versions of `msvcrt.dll'. We have
installed a workaround as from `rw1051' that seems to avoid this.
If it still happens, try extracting the one to be found in the
self-extracting archive
`ftp://ftp.microsoft.com/softlib/mslfiles/msvcrt.exe' and put it in the
`rw1063\bin' directory. Removing `msvcrt.dll' from that directory
reverts to the standard behaviour. It seems that on some versions of
Windows (but not 2000/XP) you also need to put the `rw1063\bin'
directory early in your path.
This fix has solved other problems too, for example incorrect results in
the date-time functions. However, you are probably better off
re-installing Windows.
2.16 The internet download functions fail.
==========================================
for example `update.packages' and the menu items on the Packages menu.
We have had several reports of this, although they do work for us on
_all_ of our machines. There are two known possible fixes.
(a) Use the alternative `internet2.dll' by starting R with the flag
`--internet2' (*note How do I install R for Windows?::) which uses the
Internet Explorer internals (and so needs Internet Explorer 4 or later
installed).
(b) A proxy needs to be set up: see `?download.file'.
2.17 Other strange crashes.
===========================
Some users have found that `Rgui.exe' fails to start, exiting with a
"Floating- point invalid operation" or other low level error. This
error may also happen in the middle of a session. In some cases where
we have tracked this down, it was due to bugs in the video driver on
the system in question: it makes changes to the floating point control
word which are incompatible with R. (Good practice would restore the
control word to the state it was in when the driver code was called.)
For example, one user reported that the virtual screen manager JSP2
caused this crash.
These errors are essentially impossible for us to fix or work around.
The only solution we know of is for the user to replace the buggy
driver that is causing the error.
3 Packages
**********
3.1 Can I install packages (libraries) in this version?
=======================================================
Yes, but you will need a lot of tools to do so, unless the author or the
maintainers of the `bin/windows/contrib' section on CRAN have been kind
enough to provide a pre-compiled version for Windows as a `.zip' file.
You can install pre-compiled packages either from CRAN or from a local
`.zip' file by using `install.packages': see its help page. There are
menu items on the `Packages' menu to provide a point-and-click
interface to package installation.
Note that the pre-compiled versions on CRAN are unsupported: see
`http://cran.r-project.org/bin/windows/contrib/ReadMe'.
If there is not a pre-compiled version or that is not up-to-date or you
prefer compiling from source, make sure you installed the necessary
files from `rw1063.exe'. Then read the file `readme.packages'. You
will need to collect and install several tools to use this: you can
download them via the portal at
`http://www.stats.ox.ac.uk/pub/Rtools/'. Once you have done so, just
run `Rcmd INSTALL pkgname'. To check the package (including running
all the examples on its help pages and in its test suite, if any) use
`Rcmd check pkgname': see the _`Writing R Extensions'_ manual.
Note that this is rather so tricky; please do ensure that you have
followed the instructions *exactly*. At least 90% of the questions
asked are because people have not done so.
3.2 I don't have permission to write to the `rw1063\library' directory.
=======================================================================
You can install packages anywhere and use the environment variable
`R_LIBS' (*note How do I set environment variables?::) to point to the
library location(s).
Suppose your packages are installed in `p:\myRlib'. Then you can EITHER
set the environment variable R_LIBS to p:\myRlib
OR use a package by, e.g.
library(MASS, lib.loc="p:/myRlib")
3.3 The packages I installed do not appear in the HTML help system.
===================================================================
The HTML search only works for packages installed in `rw1063\library'.
To update the HTML indices after you have installed a pre-compiled
package, run at the R prompt.
> link.html.help()
This is done automatically when installing from the Packages menu or by
`install.packages()', and when `help.start' is run, provided you have
write permission in `rw1063\library'.
3.4 My functions are not found by the HTML help search system.
==============================================================
The following conditions need to hold for functions in a package you
installed.
* the package is installed in `rw1063\library'.
* the package contains a `CONTENTS' file in its top-level directory.
* you updated the indices as described in the answer to Q3.3 after
installing the package.
If those all hold true, this works for us.
If the help search system does not work _at all_, this probably
indicates that Java support is either not installed or not enabled in
your browser. Recent versions of browsers have made Java support
optional: for example it is optional in Netscape 6/7 and in Opera, and
may not be installed for IE6 on Windows XP.
3.5 Loading a package fails.
============================
Is the package compiled for this version of R? Many of the packages
need to be compiled for a fairly recent version. (As from version
1.5.0, R will warn if a package is used that was built under a _later_
version.)
You can tell the version the package was compiled for by looking at the
`Built:' line in its `DESCRIPTION' file or at the `Version' tab of its
DLL (if it has one) in the `libs' directory. (Right-click on the DLL
in Windows Explorer and select `Version' tab of the `Properties', or
use the `DLL.version' function inside R.) If there is no `Built:' line
or version tab, the package was compiled too long ago.
3.6 Package TclTk does not work.
================================
For package `tcltk' to work (try `demo(tkdensity)' or `demo(tkttest)'
after `library(tcltk)') you need to have Tcl installed. Download
ActiveTcl 8.3.x from
`http://aspn.activestate.com/ASPN/Downloads/ActiveTcl/' and install it.
(Most of the installers that ActiveTcl uses will put the `bin'
directory containing the Tcl and Tk DLLs in your path, but you should
check. From R, run `Sys.getenv("PATH")' to do so.) Note that you do
need 8.3.x and not 8.4.0: follow the links to 8.4.0 and you will find
8.3.x available there. (If you build R from the sources yourself you
can configure it to use 8.4.0.)
You then need to set the environment variable `TCL_LIBRARY' (*note How
do I set environment variables?::), to something like `c:/Program
Files/Tcl/lib/tcl8.3'. (The startup code for the package will warn you
if this is unset. NB: do not quote the path, even if as here it
contains spaces. If you forget, you can set the variable inside R by
something like
Sys.putenv("TCL_LIBRARY"="c:/Program Files/Tcl/lib/tcl8.3")
.) Similarly, you can set the path if needed by something like
Sys.putenv(PATH=paste(Sys.getenv("PATH"), "c:/Tcl/bin", sep = ";"))
3.7 Hyperlinks in Compiled HTML sometimes do not work.
======================================================
They may well not work between packages installed in different
libraries. This is solved under Unix using symbolic links which Windows
does not implement.
3.8 `update.packages()' fails
=============================
You may not be able to update a package which is in use: Windows `locks'
the package's DLL when it is loaded. So use `update.packages()' (or
the menu equivalent) in a new session.
If you put `library(foo)' in your `.Rprofile' you will need to start R
with `--vanilla' to be able to update package `foo'.
4 Windows Features
******************
4.1 What should I expect to behave differently from the Unix version of R?
==========================================================================
* R commands can be interrupted by <Esc> in `Rgui.exe' and
<Ctrl-break> or <Ctrl-C> in `Rterm.exe': <Ctrl-C> is used for
copying in the GUI version.
* Command-line editing is always available, but is simpler than the
readline-based editing on Unix. For `Rgui.exe', the menu item
`Help | Console' will give details. For `Rterm.exe' see file
`README.rterm'.
* Using `help.start()' does not automatically send help requests to
the browser: use `options(htmlhelp=TRUE)' to turn this on.
* The HTML help system can only access packages installed in the
standard library.
* Paths to files (e.g. in `source()') can be specified with either
"/" or "\\".
* `system()' is slightly different: see its help page and that of
`shell()'.
4.2 I hear about some nifty features: please tell me about them!
================================================================
You have read the `README.rw1063'? There are file menus on the R
console, pager and graphics windows. You can source and save from
those menus, and copy the graphics to `png', `jpeg', `bmp',
`postscript', `PDF' or `metafile'. There are right-click menus giving
shortcuts to menu items, and optionally toolbars with buttons giving
shortcuts to frequent operations.
If you resize the R console the `options(width=)' is automatically set
to the console width (unless disabled in the configuration file).
The graphics has a history mechanism. As `README.rw1063' says:
`The History menu allows the recording of plots. When plots have
been recorded they can be reviewed by <PgUp> and <PgDn>, saved and
replaced. Recording can be turned on automatically (the Recording
item on the list) or individual plots can be added (Add or the
<INS> key). The whole plot history can be saved to or retrieved
from an R variable in the global environment.
There is only one graphics history shared by all the windows
devices.'
The R console and graphics windows have configuration files stored in
the `RHOME\etc' directory called `Rconsole' and `Rdevga'; you can keep
personal copies in your `HOME' directory. They contain comments which
should suffice for you to edit them to your preferences. For more
details see `?Rconsole'. There is a Preferences editor invoked from
the `Edit' menu which can be used to edit the file `Rconsole'.
4.3 Circles appear as ovals on screen
=====================================
The graphics system asks Windows for the number of pixels per inch in
the X and Y directions, and uses that to size graphics (which in R are
in units of inches). Sometimes the answer is a complete invention, and
in any case Windows will not know exactly how the horizontal and
vertical size have been set on a CRT. You can specify correct values
either in the call to `windows' or as options: see `?windows'.
(Typically these are of the order of 80.)
On one of our systems, the screen height is reported as 240mm, and the
width as 300mm in 1280 x 1024 mode and 320mm in 1280 x 960 and 1600 x
1200 modes. In fact it is a 21" monitor and 400mm x 300mm!
4.4 How do I move focus to a graphics window or the console?
============================================================
You may want to do this from within a function, for example when calling
`identify' or `readline'. Use the function `bringToTop()'. With its
default argument it brings the active graphics window to the top and
gives it focus. With argument `-1' it brings the console to the top
and gives it focus.
This works for `Rgui.exe' in MDI and SDI modes, and can be used for
graphics windows from `Rterm.exe' (although Windows may not always act
on it).
5 Workspaces
************
5.1 My workspace gets saved in a strange place: how do I stop this?
===================================================================
Have you changed the working directory?: see Q5.2.
5.2 How do I store my workspace in a different place?
=====================================================
Use the `File | Change Dir...' menu item to select a new working
directory: this defaults to the last directory you loaded a file from.
The workspace is saved in the working directory. You can also save a
snapshot of the workspace from the `Save Workspace...' menu item.
From the command line you can change the working directory by the
function `setwd': see its help page.
5.3 Can I load workspaces saved under Unix/GNU-Linux?
=====================================================
Yes. All ports of R use the same format for workspaces, so they are
interchangeable (for the same 1.x.? version of R, at least).
6 The R Console and Fonts
*************************
6.1 I would like to be able to use Japanese fonts
=================================================
for example, in the console and to annotate graphs.
We believe this is possible by setting suitable fonts in the Rconsole
and Rdevga configuration files (see Q4.2). You can specify additional
fonts in Rdevga, and use them by
par(font=, font.lab=, font.main=, font.sub=)
Nineteen fonts are specified (as 1 to 19) by default: you can add to
these (up to 13 more) or replace them.
6.2 I don't see characters with accents at the R console, for example in ?text.
===============================================================================
You need to specify a font in Rconsole (see Q4.2) that supports Latin1
encoding. The default, `Courier New', does on our systems, as does
`FixedSys'. This may be a problem in other locales, especially for
non-Western European languages.
Support for these characters within `Rterm' depends on the environment
(the terminal window and shell, including locale settings) within which
it is run as well as the font used by the terminal window.
6.3 When using Rgui the output to the console seems to be delayed.
==================================================================
This is deliberate: the console output is buffered and re-written in
chunks to be faster and less distracting. You can turn buffering off or
on from the `Misc' menu or the right-click menu: <Ctrl-W> toggles the
setting.
If you are sourcing R code or writing from a function, there is another
option. A call to the R function `flush.console()' will write out the
buffer and so update the console.
6.4 Long lines in the console or pager are truncated.
=====================================================
They only *seem* to be truncated: that $ at the end indicates you can
scroll the window to see the rest of the line. Use the horizontal
scrollbar or the <CTRL + left/right arrow> keys to scroll horizontally.
7 Building from Source
**********************
7.1 How can I compile R from source?
====================================
Get the R sources. Suppose you want to compile R-1.6.2. Start in a
directory whose path does not contain spaces, and run
tar zxvf R-1.6.2.tgz
cd R-1.6.2
cd src\gnuwin32
Now read the `INSTALL' file and set up all the tools needed. Then you
can just use `make', sit back and wait. (A complete build takes about
5 minutes on a 1GHz PIII with a fast local disc.)
You may need to compile under a case-honouring file system: we found
that a `samba'-mounted file system (which maps all file names to lower
case) did not work.
7.2 Can I use a fast BLAS?
==========================
Fast BLAS (Basic Linear Algebra Subprograms,
`http://www.netlib.org/blas/faq.html') routines are used to speed up
numerical linear algebra. There is support in the R sources for the
`tuned' BLAS called ATLAS (`http://math-atlas.sourceforge.net'). The
savings can be appreciable: on a 366MHz PIIM and a 1000 x 1000 matrix
`La.svd' took 182 sec with the standard BLAS and 59 sec with ATLAS.
Because ATLAS is tuned to a particular chip we can't use it generally:
the optimal routines for a PIII or an Athlon XP are quite different and
neither will not run at all on a PII.
BLAS support is supplied by the single DLL `R_HOME\bin\Rblas.dll', and
you can add a fast BLAS just by replacing that. Replacements for some
of the more common chips are available on CRAN in directory
`bin/windows/contrib/ATLAS'.
If you are building R from source, in the file `MkRules' there are
macros `USE_ATLAS' and `ATLAS_PATH'. Set `USE_ATLAS = YES' and
`ATLAS_PATH' to where the ATLAS libraries are located. You will need
to make the libraries yourself: none of the binaries we have seen are
compiled for the correct compiler.
7.3 How do I include compiled C code?
=====================================
We strongly encourage you to do this _via_ building an R package: see
the _`Writing R Extensions'_ manual. In any event you should install
the parts of the R system for building R packages (in `rw1063.exe'),
and get and install the tools (including Perl) and compilers mentioned
in the file `readme.packages' contained therein. Then you can use
...\bin\Rcmd SHLIB foo.c bar.f
to make `foo.dll'. Use `...\bin\Rcmd SHLIB --help' for further
options, or see `?SHLIB'.
If you want to use Visual C++, Borland C++ or other compilers, see the
appropriate section in `readme.packages'.
7.4 How do I debug code that I have compiled and dyn.load-ed?
=============================================================
You will need a suitable version of `gdb': we normally use that from
the Cygwin distribution. Debugging under Windows is often a fraught
process, and sometimes does not work at all. If all you need is a
_just-in-time_ debugger to catch crashes, consider `Dr. Mingw' from
`http://mefriss1.swan.ac.uk/~jfonseca/gnu-win32/software/drmingw/'.
That will be able to pinpoint the error, most effectively if you build a
version of R with debugging information as described below.
First, build a version of the R system with debugging information by
make clean
make DEBUG=T
and make a debug version of your package by
make pkgclean-mypkg
make DEBUG=T pkg-mypkg
Then you can debug by
gdb /path/to/rw1063/bin/Rgui.exe
However, note
* `gdb' will only be able to find the source code if we run in the
location where the source was compiled (`rw1063/src/gnuwin32' for
the main system, `rw1063/src/library/mypkg/src' for a package),
unless told otherwise by the `directory' command. It is most
convenient to set a list of code locations via `directory' commands
in the file `.gdbinit' in the directory from which `gdb' is run.
* It is only possible to set breakpoints in a DLL after the DLL has
been loaded. So a way to examine the function `tukeyline' in
package `eda' might be
gdb ../../../../bin/Rgui.exe
(gdb) break WinMain
(gdb) run
[ stops with R.dll loaded ]
(gdb) break R_ReadConsole
(gdb) continue
[ stops with console running ]
(gdb) continue
Rconsole> library(eda)
(gdb) break tukeyline
(gdb) clear R_ReadConsole
(gdb) continue
Fortran symbols need an underline appended.
* Windows has little support for signals, so the usual idea of
running a program under a debugger and sending it a signal to
interrupt it and drop control back to the debugger does not work
with a `mingw' version of `gdb'. It does often work with the
`cygwin' version.
7.5 How do I include C++ code?
==============================
You need to do two things:
(a) Write a wrapper to export the symbols you want to call from R as
`extern "C"'.
(b) Include the C++ libraries in the link to make the DLL. Suppose
`X.cc' contains your C++ code, and `X_main.cc' is the wrapper, as in
the example in _`Writing R Extensions'_. Then build the DLL by (`gcc')
...\bin\Rcmd SHLIB X.cc X_main.cc
or (VC++, which requires extension `.cpp')
cl /MT /c X.cpp X_main.cpp
link /dll /out:X.dll /export:X_main X.obj X_main.obj
or (Borland C++, which also requires extension `.cpp')
bcc32 -u- -WDE X.cpp X_main.cpp
and call the entry point(s) in `X_R', such as `X_main'. Construction
of static variables will occur when the DLL is loaded, and destruction
when the DLL is unloaded, usually when R terminates.
Note that you will not see the messages from this example in the GUI
console: see the next section.
This example is in package `cxx_0.0-x.tar.gz' in the
`src/contrib/Devel' section on CRAN, and that can be compiled as a
package in the usual way on Windows.
7.6 The output from my C code disappears. Why?
===============================================
The `Rgui.exe' console is a Windows application: writing to `stdout' or
`stderr' will not produce output in the console. (This will work with
`Rterm.exe'.) Use `Rprintf' or `REprintf' instead. These are declared
in header file `R_ext/PrtUtil.h'.
Note that output from the console is delayed (*note The output to the
console seems to be delayed::), so that you will not normally see any
output before returning to the R prompt.
7.7 The output from my Fortran code disappears. Why?
=====================================================
Writing to Fortran output writes to a file, not the `Rgui' console.
Use one of the subroutines `dblepr', `intpr' or `realpr' documented in
the _`Writing R Extensions'_ manual.
Note that output from the console is delayed (*note The output to the
console seems to be delayed::), so that you will not normally see any
output before returning to the R prompt even when using the `xxxpr'
subroutines.
7.8 The console freezes when my compiled code is running.
=========================================================
The console, pagers and graphics window all run in the same thread as
the R engine. To allow the console etc to respond to Windows events,
call `R_ProcessEvents()' periodically from your compiled code. If you
want output to be updated on the console, call `R_FlushConsole()' and
then `R_ProcessEvents()'.
Last edited 2002 December 24 by Professor B. D. Ripley
<ripley@stats.ox.ac.uk>