I have a program that generating 2D arrays with different number of rows and appending them to list. I need to combine that list into one 3D array of 2D arrays.

A = np.zeros(15).reshape(3,5)
B = np.zeros(20).reshape(4,5)
C = np.zeros(25).reshape(5,5)
lst = [A, B, C][array([[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.]]), array([[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.]]), array([[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.],[0., 0., 0., 0., 0.]])]

Needs 3D array that looks like this

[[[0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.]] [[0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.]][[0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.][0. 0. 0. 0. 0.]]]

Use the tolist method:

lst = [A.tolist(), B.tolist(), C.tolist()]

Or more generic:

lst_of_arrays = [A, B, C] # Could be initialized differently
lst = [ar.tolist() for ar in lst_of_arrays ]