Data stream classification with artificial endocrine system

Due to concept drifts, maintaining an up-to-date model is a challenging task for most of the current classification approaches used in data stream mining. Both the incremental classifiers and the ensemble classifiers spend most of their time in updating their temporary models and at the same time, a big sample buffer for training a classifier is necessary for most of them. These two drawbacks constrain further application in classifying a data stream. In this paper, we present a hormone based nearest neighbor classification algorithm for data stream classification, in which the classifier is updated every time a new record arrives. The records could be seen as locations in the feature space, and each location can accommodate only one endocrine cell. The classifier consists of endocrine cells on the boundaries of different classes. Every time a new record arrives, the cell that resides in the most unfit location will move to the new arrived record. In this way, the changing boundaries between different classes are recorded by the locations where endocrine cells reside in. The main advantages of the proposed method are the saving of the sample buffer and the improving of the classification accuracy. It is very important for conditions where the hardware resources are very expensive or the main memory is limited. Experiments on synthetic and real life data sets show that the proposed algorithm is able to classify data streams with less memory space and classification error.