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+Title: Graphing the Norwegian company ownership structure
+Tags: english, offentlig innsyn
+Date: 2015-06-15 13:50
+
+<p>It is a bit work to figure out the ownership structure of companies
+in Norway.  The information is publicly available, but one need to
+recursively look up ownership in all owners to figure out the complete
+ownership graph of a given set of companies.  To save me the work in
+the future, I wrote a script to do this automatically, outputting the
+ownership structure using the Graphviz/dotty format.  The data source
+is web scraping from <a href="http://www.proff.no/">Proff</a>, because
+I failed to find a useful source directly from the official keepers of
+the ownership data, <a href="http://www.brreg.no/">Brønnøysundsregistrene</a>.</p>
+
+<p>To get a owner ship graph, fetch the code from git and run it using
+the organisation number.  I'm using the Norwegian newspaper Dagbladet
+as an example here, as its ownership structure is very simple:</p>
+
+<pre>
+% time ./bin/eierskap-dotty 958033540 > dagbladet.dot
+
+real    0m2.841s
+user    0m0.184s
+sys     0m0.036s
+%
+</pre>
+
+<p>The script accept several organisation numbers on the command line,
+allowing a cluster of companies to be graphed in the same image.  The
+resulting dot file for the example above look like this.  The edges
+are labeled with the ownership percentage, and the nodes uses the
+organisation number as their name and the name as the label:</p>
+
+<pre>
+digraph ownership {
+rankdir = LR;
+"Aller Holding A/s" -> "910119877" [label="100%"]
+"910119877" -> "998689015" [label="100%"]
+"998689015" -> "958033540" [label="99%"]
+"974530600" -> "958033540" [label="1%"]
+"958033540" [label="AS DAGBLADET"]
+"998689015" [label="Berner Media Holding AS"]
+"974530600" [label="Dagbladets Stiftelse"]
+"910119877" [label="Aller Media AS"]
+}
+</pre>
+
+<p>To view the ownership graph, run "<tt>dotty dagbladet.dot</tt>" or
+convert it to a PNG using "<tt>dot -T png dagbladet.dot >
+dagbladet.png</tt>".  This is the result can be seen below:</p>
+
+<img src="http://people.skolelinux.org/pere/blog/images/2015-06-15-ownership-graphs-norway-dagbladet.png" width="80%">
+
+<p>Note that I suspect the "Aller Holding A/S" entry to be incorrect
+data in the official ownership register, as that name is not
+registered in the official company register for Norway.  The ownership
+register is sensitive to typos and there seem to be no strict checking
+of the ownership information.</p>
+
+<p>Let me know if you improve the script or find better data sources.
+The code is licensed according to GPL 2 or newer.</p>

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