Compute histogram using divisions in bins.
Count the number of times values from array a fall into numerical ranges defined by bins. Range x is given by bins[x] <= range_x < bins[x+1] where x =0,N and N is the length of the bins array. The last range is given by bins[N] <= range_N < infinity. Values less than bins are not included in the histogram.
a : array_like of rank 1
bins : array_like of rank 1
histogram2 : ndarray of rank 1