access rows and columns of numpy array code example

Example 1: get column or row of matrix array numpy python

test = numpy.array([[1, 2], [3, 4], [5, 6]])
column = test[:,0]
# column == array([1, 3, 5])
row = test[1,:]
# row == array([3, 4])

Example 2: how to get the first few lines of an ndarray

In [11]: a[:,:2]
Out[11]: 
array([[-0.57098887, -0.4274751 ],
       [-0.22279713, -0.51723555],
       [ 0.67492385, -0.69294472],
       [ 0.41086611,  0.26374238]])