[2014/11/30: Updated the L1-norm vs L2-norm loss function via a programmatic validated diagram. Thanks readers for the pointing out the confusing diagram. Next time I will not draw mspaint but actually plot it out.] While practicing machine learning, you may have come upon a choice of the mysterious L1 vs L2. Usually the two decisions are : 1) L1-norm vs L2-norm loss function; and 2) L1-regulariza