Subjects by keywords.

Each library buys books, journals or access to the e-version of these, files, databases, etc. In each library, there is a specific focus on a particular field of interest or -more often- multiple fields of interest. In the library of the Peace Palace 'documents' are acquired in the field of international law. Of course it is possible to recognize a large number of sub fields within this vast subject: international criminal law, human rights, diplomacy and so on.

For the users of the library, it is important to know which of these areas are covered and whether therefore it is worthwhile to use that library when you yourself are dealing with such a subject. One of the tools the library is using, is a system of sending regular 'alerts'. Interested scholars, students and other interested parties can be informed about the most recent acquisitions, once a week. There are around 1.000 subscribers to this service. They receive a weekly overview, based on a single criterion. The consequence of using a single general criterion is of course that the outcome may be huge. Especially topics like 'European Union' or 'Public International Law' may contain quite a lot of bibliographical references.

But what if you have a way of presenting the acquisitions in one month, not on the basis of one single general criterion, but where combinations of keywords assigned to each title play a role? What if relationships between those keywords can be visualized on the website in stead of emailed to a subscriber? In an attempt to make that possible I created a clickable map, which can be found on http://www.ppl.nl/september.

To create this map I used the visualization tool 'Gephi', which is especially strong in showing the links between the building blocks of the map. So I consider, for this purpose, the keywords as building blocks. On above mentioned web address, the acquisitions from the month of September are recorded, not in the form of boring title lists, but in the form of assigned keywords and relationships between those keywords. It is still all about numbers, as the strength of a relation is determined by the amount of occurrences of keyword pairs.

Of course in a batch of thousands of titles some areas in the map should be indicated by large blobs of tightly connected keywords. These blobs refer to the core businesses of the library. At the edges of the map, smaller subareas appear. In other words, large areas of the map show acquisitions that are always extremely important to the library. They can be recognized, because the largest circles in the map appear over there, surrounded by a large amount of closely packed smaller circles.


Subtopics are located outside the center of the map and can be considered as subjects which are farther away from the core business. So the area in the upper right is characterized by the keyword 'History', especially the history of the First World War. Typical related keywords are: 'Military History', 'Massacres', 'Ethnic Minorities', 'Russian Empire', etc. In the bottom left there is an area that relates to commerce, trade, international commercial arbitration, etc.

It must be stressed that subareas differ each month. It all depends on what is going on in the world. Highlighted in the last couple of months of this year is of course the commemoration of the start of the First World War. But other current events can also lead to a temporary increase in attention, such as transboundary pollution of the environment, disease outbreak, cyber warfare, sporting events, etc.

Clicking on a circle produces an 'Information Pane' where additional information can be found on that keyword, like how many times it occurs, but also the related keywords -those that are used in combination with the clicked keyword- are mentioned. So, with a few clicks it is easy to get a good impression about different topics and topic areas.

Finally, you are invited to use the map by hovering over the various items and view the information in the right pane. Are you looking for a specific topic? You can search by using the Search box in the left panel or zoom in on a specific group or cluster by 'Group Selector'.