Efficient handling of high-dimensional feature spaces by randomized classifier ensembles

Handling massive datasets is a difficult problem not only due to prohibitively large numbers of entries but in some cases also due to the very high dimensionality of the data. Often, severe feature selection is performed to limit the number of attributes to a manageable size, which unfortunately can lead to a loss of useful information. Feature space reduction may well be necessary for many stand-alone classifiers, but recent advances in the area of ensemble classifier techniques indicate that overall accurate classifier aggregates can be learned even if each individual classifier operates on incomplete "feature view" training data, i.e., such where certain input attributes are excluded. In fact, by using only small random subsets of features to build individual component classifiers, surprisingly accurate and robust models can be created. In this work we demonstrate how these types of architectures effectively reduce the feature space for submodels and groups of sub-models, which lends itself to efficient sequential and/or parallel implementations. Experiments with a randomized version of Adaboost are used to support our arguments, using the text classification task as an example.