Tuesday, February 16, 2016

Compressive PCA on Graphs

Another matrix factorization on graphs:

Compressive PCA on Graphs by Nauman Shahid, Nathanael Perraudin, Gilles Puy, Pierre Vandergheynst

Randomized algorithms reduce the complexity of low-rank recovery methods only w.r.t dimension p of a big dataset YRp×n. However, the case of large n is cumbersome to tackle without sacrificing the recovery. The recently introduced Fast Robust PCA on Graphs (FRPCAG) approximates a recovery method for matrices which are low-rank on graphs constructed between their rows and columns. In this paper we provide a novel framework, Compressive PCA on Graphs (CPCA) for an approximate recovery of such data matrices from sampled measurements. We introduce a RIP condition for low-rank matrices on graphs which enables efficient sampling of the rows and columns to perform FRPCAG on the sampled matrix. Several efficient, parallel and parameter-free decoders are presented along with their theoretical analysis for the low-rank recovery and clustering applications of PCA. On a single core machine, CPCA gains a speed up of p/k over FRPCAG, where k is much less than p is the subspace dimension. Numerically, CPCA can efficiently cluster 70,000 MNIST digits in less than a minute and recover a low-rank matrix of size 10304 X 1000 in 15 secs, which is 6 and 100 times faster than FRPCAG and exact recovery.

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