What does np.r_ do (numpy)?

Question

Following code is taken from numpy function base on github

sa = sort(a[i:i+block])
n += np.r_[sa.searchsorted(bins[:-1], \'left\'),
           sa.searchsorted(bin         


        

Answer 1

What it does is row-wise merging. This post has some nice example:

>>>V = array([1,2,3,4,5,6 ])
>>>Y = array([7,8,9,10,11,12])
>>>np.r_[V[0:2],Y[0],V[3],Y[1:3],V[4:],Y[4:]]
array([ 1,  2,  7,  4,  8,  9,  5,  6, 11, 12])

Read more about it in this , and in the documentation of numpy.