Networks / Pajek
	Package for Large Network Analysis

How to
visualize genealogies with Pajek

 I would like to use Pajek for laying out an old family tree, people
 around 1530, in GEDCOM format.
 I need a special layout because there used to be a lot of 2nd, 3rd
 or 4th weddings and other "incidents".

 I have donwloaded pajek and wanted to play with it but couldn't find
 the right options to use to layout a standard GEDCOM file.
 When I download the "Oldham.ged" file for testing, Pajek recognize
 the format and generates FAMS number in the "vector" line.  From that,
 all I can do is generate a circular layout with the "draw" button
 (I need to increase the number of vertices in the option menu first.)

 Could you provide me with a simple sequence of operations I should
 perform to layout the family graph nicely?
 --
  Jean-Daniel Fekete

Let us take the Oldham.ged as an example. Download it and read into Pajek. We shall represent the genelogy as a p-graph. For details on p-graphs see the Douglas White's P-graphs page.

Options/Read-write/Gedcom-Pgraph ON
Options/Max vertices to draw 10000
read Ged file ... using network read buttun
Info/general/network

The network has 17804 vertices and 17661 arcs. Usually several (weakly connected) components exist in large genealogies. They can (should?) be analysed separately.

Net/Components/Weak 2
Info/partition

There are 153 nontrivial weak components (clusters); cluster 18 has 1117 vertices. Let's extract it and produce an initial layout using macro LAYERS.

Operations/Extract from network/Partition 18 18
Macro/Play .../pajek/macro/genea/layers.mcr
Draw/Draw partition
Layers/Resolution/Low
Layers/Optimize .../Complete
Move/Fix/y

Now we can manually edit the obtained picture. Press right mouse button and select a subregion to edit. To return to the complete picture select the option Redraw.

p-graphs usually contain a lot of subtrees. The interesting cases (marriages between relatives) are in the biconnected parts - you can identify them using

Components/Bi-components

or, simply by removing the subtrees by

Net/Transform/Reduction/Degree/All 2 Yes

We get a network on 840 vertices. Again there can be several components.

Net/Components/Weak 2
Info/partition

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