Flatten numpy array without double for loop

Question

I have a 2-d matrix. For the purposes of this example, let\'s say it is a random matrix

>>> a = np.random.randn(5, 7)
>>> a
array([[-0.3727         


        

Answer 1

Use np.meshgrid to create 2D meshes corresponding to X and Y labels and then stack them as columns alongwith the 2D input array a, like so -

X,Y = np.meshgrid(label_x,label_y)
out = np.column_stack((Y.ravel(),X.ravel(),a.ravel()))