# http://es.stackoverflow.com/q/21370/127
import numpy as np

A=np.array([[ 0.,   0.1,   0.2,   0.3,   0.45],
   		   [ 1.2,   1.4,   1.6,   2.8,   3.92],
		   [ 2.1,   1.8,   2.4,   2.2,   4.7 ],
   		   [ 3.2,   3.4,   5.1,   6.2,   5.22]])
   
print A

A[A<=2] = 0
print A