DragonFly On-Line Manual Pages

XGVis(1)               DragonFly General Commands Manual              XGVis(1)

NAME
       xgvis - interactive multidimensional scaling using xgobi for display

SYNOPSIS
       xgvis [ -dims n ] [ -stepsize x ] fname

DESCRIPTION
       xgvis is an interactive multidimensional scaling (MDS) program that
       consists of a control panel to manipulate the parameters of the MDS
       stress function and an xgobi window for data display.  It can be used
       either for visualization of dissimilarity data, for dimension
       reduction, or for graph layout.  Graph layout is usually done in 2D,
       but xgvis allows layouts in arbitrary dimensions, 3D being the default.
       It permits missing values, which can be used to implement
       multidimensional unfolding.

       It is used as follows:

         o Start up with a user-supplied or random starting configuration.

         o Initiate MDS optimization.  As the optimization algorithm does its
           work, observe both the changing stress values and the animated
           point configuration.

         o Examine the optimized configuration with 3D rotations and grand
           tours and drill-down operations such as labeling and linked
           brushing.

         o Enhance the configuration with glyphs, colors and lines for
           interpretation.

         o Modifiy the dissimilarities, the stress function, and/or the
           configuration by

             - transforming the dissimilarities

             - choosing weights or cutting extreme dissimilarities

             - restricting MDS to subsets

             - hand editing the existing configuration or

             - selecting a new random configuration

OPTIONS
       -dims n

         Specify n, the dimensionality of the embedding space.  By default,
         its value is 3.

       -stepsize x

         Specify the initial stepsize; its default value is 0.1.

FILES
       XGVis uses a set of input files with a common root (which we'll call
       fname in the man page) and a suffix.  First, each set must contain a
       file with the suffix .edges, .dat or .dist.

       fname.dist
         Distance matrix: an n x n matrix, with entries separated by white
         space and one row per line.

       fname.edges
         Line segments: specifications for the pattern of line segments which
         connect pairs of points.  The file must contain at least two numbers
         per line.  The first two numbers represent the row numbers of the two
         points that should be connected.  (This is exactly like the structure
         of a fname.lines file in xgobi.)  In addition, if a third number is
         present, it is taken to be an edge weight.

         If this line is present and the distance matrix is absent, then the
         distance matrix is computed from it, with each edge representing a
         distance of one.

       fname.dat
       fname.pos
         Starting positions:  an n x p matrix, with entries separated by white
         space and one row per line.

         If this file is present and a distance file is absent, the distance
         matrix is computed from it.

       fname.lines

         Line segments: specifications for the pattern of line segments which
         connect pairs of points.  If this file is present, then the edges
         file is used to create the distance matrix but the lines file is used
         to draw the edges.

       Many additional files can be specified.  See the xgobi man page for
       descriptions of fname.col (variable labels), fname.row (case labels),
       fname.colors (glyph colors), and fname.linecolors (line colors), in
       particular.

AUTHORS
       Andreas Buja (andreas@research.att.com)
       Deborah Swayne (dfs@research.att.com)

CONTACT
       Deborah Swayne (dfs@research.att.com)

SEE ALSO
       Sample data files are included in the XGVis distribution.

       For papers and further pointers, check the following web page:
       http://www.research.att.com/areas/stat/xgobi/

BUGS
       Probably too numerous to mention, but you do the authors a favor if you
       report the ones you notice.

                               20 November 1998                       XGVis(1)