Stack columns in numpy 2-dim array to get 1-dim array

Question

How to stack all columns in a 2-dimensional Numpy array into a 1-dimensional array.

I.e. I have:

x = np.array([[1, 3, 5],[2, 4, 6]])

And I want to get:

np.array([1, 2, 3, 4, 5, 6])

Is there a way to achieve this without a loop or list comprehension?

Answer 1

You can use ravel:

x = np.array([[1, 3, 5],[2, 4, 6]])

res = x.ravel('F')  # or x.T.ravel()

# array([1, 2, 3, 4, 5, 6])

Answer 2

Using flatten with 'F'

x.flatten('F')
Out[114]: array([1, 2, 3, 4, 5, 6])