Monday, January 4, 2010

Dealing with very large dataset in Sipina

The ability to handle large databases is a crucial problem in the data mining context. We want to handle a large dataset in order to detect the hidden information. Most of the free data mining tools have problems with large dataset because they load all the instances and variables into memory. Thus, the limitation of these tools is the available memory.

To overcome this limitation, we should design solutions that allow to copy all or part of the data on disk, and perform treatments by loading into memory only what is necessary at each step of the algorithm (the instances and/or the variables). If the solution is theoretically simple, it is difficult in practice. Indeed, the processing time should remain reasonable even if we increase the disk access. It is very difficult to implement a strategy that is effective regardless of the learning algorithm used (supervised learning, clustering, factorial analysis, etc.). They handle the data in very different way: some of them use intensively matrix operations; the others search mainly the co-occurrence between attribute-value pairs, etc.

In this tutorial, we present a specific solution in the induction tree context. The solution is integrated into SIPINA (as optional) because its internal data structure is especially intended to the decision tree induction. Developing an approach which takes advantages of the specificities of the learning algorithm was easy in this context. We show that it is then possible to handle a very large dataset (41 variables and 9,634,198 observations) and to use all the functionalities of the tool (interactive construction of the tree, local descriptive statistics on nodes, etc.).

To fully appreciate the solution proposed by Sipina, we compare its behavior to generalist data mining tools such as Tanagra 1.4.33 or Knime 2.03.

Keywords: very large dataset, decision tree, sampling, sipina, knime
Components: ID3
Lien : en_Sipina_Large_Dataset.pdf
Données :
Références :
Tanagra, « Decision tree and large dataset ».
Tanagra, « Local sampling for decision tree learning »