FcaStone: software for FCA file format conversion and interoperability

• Introduction
• FcaStone and FcaFlint
• Examples of lattices generated with the software
• Downloading the software
• Installation on Unix, Linux, Mac OS X
• Installation on Windows
• Installation of Graphviz
• Supported Formats
• How to format the labels in the lattice diagrams
• Running the command/man page
• More details on using FcaStone with other tools
• Troubleshooting/FAQ

FcaStone can

• convert between commonly used FCA file formats (cxt, cex, csc, slf, bin.xml, and csx).
• convert between FCA file formats and comma separated value (csv) files as exported from and imported into databases and spreadsheets.
• convert formal contexts into the xfig format or into Bernhard Ganter's latex format.
• convert concept lattices into graph formats (dot, gxl, gml, ...) for use by graph editors (yEd, jgraph, ...) or into vector graphics formats (fig, svg, ...) for use by vector graphics editors (Xfig, Dia, Inkscape, ...).
• convert formal contexts into lattice diagrams (using Graphviz's layout).
• serve as a component of a server-side script for generating lattices on webpages.

Cautions:

• this software is in an alpha release state, i.e. for developer testing. Not everything will work. What to do if you find a bug.
• The emphasis of FcaStone is on converting file formats, not on fast algorithms for lattice construction which are already provided by other FCA software. FcaStone will take several seconds to compute a lattice with 100 concepts.

• Converting lattices between different formats in a manner that preserves the graph layout of the lattice. (This would also mean that other FCA software such as Galicia or Colibri could be called from FcaStone in order to obtain layouts and efficiency.)
• Database connectivity.
• Convert into other knowledge representation formats (conceptual structures, semantic web), if they are suitable for representing lattices.

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FcaStone can be downloaded as a zip archive which contains the fcastone and fcaflint executable scripts, the licence and readme files.

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2a) If you have administrator privileges, you should copy the file to a shared bin directory (eg /usr/local/bin) and change the file permission to executable:

sudo mv fcastone /usr/local/bin
sudo chmod 755 /usr/local/bin/fcastone

b) If you do not have administrator privileges, then you should move the file to a bin directory that you have access to and that is in your path (or create a bin directory under your home directory if it does not already exist).

mkdir ~/bin
mv fcastone ~/bin
chmod 755 ~/bin/fcastone

If this bin directory is not in your path, then you need to add it to your PATH variable (see here for further information on changing the Unix PATH variable).

3) If you are getting a "command not found" error right after installation, you'll need to run something like "rehash" or, alternatively, you could logout/login at this point. Also, check the location of perl (for example by typing "which perl"). Perl is expected to be installed in /usr/bin. If necessary, edit the first line of the fcastone executable so that it contains the correct location of your perl installation.

Installation on Windows

Information about installing Perl can be found here. I have tested installing ActivePerl, which is freely available and can be downloaded as an msi file. The default installation sets the PATH variable so that it can find the Perl executable. This website contains a short tutorial on installing ActivePerl and on how to use the DOS prompt.

2) In order to avoid having to type long path names, it is probably easiest to move the fcastone file into a directory which also contains the FCA files that are to be used. The fcastone file can be changed to executable format, or it can be executed by preceding it with perl, i.e., "perl fcastone ...". It might be useful to rename fcastone to fcastone.pl, so that Windows knows the filetype.

Linux, Mac OS X and Windows: Installation of Graphviz

The table below shows which features require Graphviz and which don't.

Note for use on a webserver: unfortunately, it may be impossible to install Graphviz on a webserver on a commercially hosted account (unless you can find a statically compiled version of the dot executable which can be copied to the webserver), because service providers don't usually give out administrator passwords. It should be possible, however, to install Graphviz on a virtual private server (because such accounts come with administrator privileges).

FcaStone passes the data straight to Graphviz. This means that only those output file formats are available which are supported by the local Graphviz installation. If the labels in the lattice diagrams are not readable, then there is a problem with Graphviz's ability to find the local fonts (see Graphviz's documentation). If one of the formats does not work, try another (eg. gif instead of jpg). The file fcaStoneDotErrors.log shows the errors and warnings produced by Graphviz. The name of this file can be changed or it can be suppressed by editing the line that starts with "my $errorslocation = " in fcastone.

If Graphviz is installed in a location that is not in the main Shell path, it is useful to uncomment the line in fcastone that starts with "# $dotlocation = " and edit it to point to the location of dot.

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Many tools for image conversion exist elsewhere. Depending on the local Graphviz installation, more options may be available (eg. running "dot -Tdia -o outputfilename inputFileInDotFormat" on Linux will produce output suitable for the Dia program). Programs such as ps2eps, fig2dev, ImageMagick's "convert", etc provide further options for file conversions.

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Two lattice designs are available (see some examples). Using the -b option, each node is represented as a box. The objects are listed in the bottom half, the attributes in the top half. The advantage of this format is that the labels never overlap because Graphviz will adjust the box sizes depending on the label sizes. The disadvantage is that this is not the standard FCA way of representing lattices. The other design (which is default) is more similar to traditional FCA lattices, with the disadvantage that labels can overlap. The -t option only applies to the second design. These design choices are based on what can be stored in the dot format. The gml output of FcaStone just places the labels across the nodes, which is not satisfactory. Therefore, gml output should only be used if the lattice is afterwards manually edited.

In general, automatically generated lattices will probably never be as perfect as hand drawn ones. If perfect lattice pictures are desired, then traditional FCA tools should be used. FcaStone's facility for lattice generation is more aimed at applications in which the lattices cannot be hand drawn (such as automatically generated ones on webpages) and don't need to be perfect (for example, because they are just used to provide a rough sketch of what the lattice looks like).

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fcastone waters.cxt waters.cex
fcastone -g waters.cxt waters.fig

Use on a website (Perl, explanation below):

#!/usr/local/bin/perl
use CGI;
print "Content-type: image/gif\n\n";
$fcacontent = "object1,attr1\n object1,attr2\n";
open (PIPE, "| fcastone -w -b format.csv format.gif");
print PIPE $fcacontent;
close PIPE;

Use on a website (PHP, explanation below):

<?php
header("Content-type: text/html");
$fcacontent = "object1,attr1\n object1,attr2\n";
$descriptorspec = array(0 => array("pipe", "r"),1 => array("pipe", "w") );
$process = proc_open('/usr/local/bin/fcastone -w -b format.csv format.cxt',$descriptors\
pec,$pipes);

if (is_resource($process)) {

fwrite($pipes[0],  "$fcacontent");
fclose($pipes[0]);
while (! feof($pipes[1])) {$retval .= fgets($pipes[1]);}
echo $retval;
fclose($pipes[1]);
$return_value = proc_close($process);
}
?>

In these examples, format.csv and format.gif are just strings that indicate which formats are used for input and output; they are not filenames. The variable $fcacontent contains a context in csv format. SECURITY WARNING: any form variables that are piped into a program must be carefully checked for insecure data because otherwise a hacker might be able to execute any command on the server. For further explanations of this risk, do a websearch on "user submitted data" "security".

Also, see the troubleshooting comments below.

fcaStoneDotErrors.log
(This file is created in the current directory and contains any errors or warnings produced by running Graphviz's dot.)

This version is an alpha release of the software. I am sure there are still many bugs in the software. If you find a bug, please, send me an email (see http://www.upriss.org.uk for my current email address). Please, include the following in your email: 1) the command-line that you used, 2) the name of the operating system of your computer, 3) a short description of the problem, 4) the input file as an attachment.

This program was written by Uta Priss (http://www.upriss.org.uk). More information on FCA can be found at (http://www.upriss.org.uk/fca/).

The algorithm for calculating the concepts is an implementation of Bernhard Ganter's algorithm described in "Two basic algorithms in concept analysis." Technische Hochschule Darmstadt, FB4-Preprint, 831, 1984. (It's slow because it's implemented using strings - the algorithm itself is fine.)