The concept of weight pruning has shown success in neural network model compression with marginal loss in classification performance. However, similar concepts have not been well recognized in improving unsupervised learning. To the best of our knowledge, this paper proposes one of the first studies on weight pruning in unsupervised autoencoder models using non-imaging data points. We adapt the weight pruning concept to investigate the dynamic behavior of weights while reconstructing data using an autoencoder and propose a deterministic model perturbation algorithm based on the weight statistics. The model perturbation at periodic intervals resets a percentage of weight values using a binary weight mask. Experiments across eight non-imaging data sets ranging from gene sequence to swarm behavior data show that only a few periodic perturbations of weights improve the data reconstruction accuracy of autoencoders and additionally introduce model compression. All data sets yield a small portion of (<5%) weights that are substantially higher than the mean weight value. These weights are found to be much more informative than a substantial portion (>90%) of the weights with negative values. In general, the perturbation of low or negative weight values at periodic intervals has improved the data reconstruction loss for most data sets when compared to the case without perturbation. The proposed approach may help explain and correct the dynamic behavior of neural network models in a deterministic way for data reconstruction and obtaining a more accurate representation of latent variables using autoencoders.
Keywords: activation function; autoencoder; data reconstruction; model compression; weight masking; weight pruning.