Q:

collapse a list of ndarray to a matrix

I have a list containing objects of type numpy.ndarray, all list elements has same .shape value. 
How can I collapse this into a matrix? 

A:

Sounds like you're looking for numpy.vstack() or numpy.hstack(), depending on whether you want the arrays to become the rows or the columns of the matrix. 
From the manual:
>>> a = np.array([1, 2, 3])
>>> b = np.array([2, 3, 4])
>>> np.vstack((a,b))
array([[1, 2, 3],
       [2, 3, 4]])

A:

I am not sure if you mean this:
>>> alist = [np.array([item, item+1]) for item in range(5)]
>>> alist
[array([0, 1]), array([1, 2]), array([2, 3]), array([3, 4]), array([4, 5])]

>>> np.array(alist)
array([[ 0,  1],
       [ 1,  2],
       [ 2,  3],
       [ 3,  4],
       [ 4,  5]])
>>> 

or actually you want a matrix:
>>> np.matrix(alist)
matrix([[ 0,  1],
        [ 1,  2],
        [ 2,  3],
        [ 3,  4],
        [ 4,  5]])

