Python How to make array in array?
You can't make that array. Arrays is numpy are similar to matrices in math. They have to be mrows, each having n columns. Use a list of lists, or list of np.arrays
I have a numpy array Z1, Z2, Z3:
    Z1 = [1,2,3]
    Z2 = [4,5]
    Z3 = [6,7,8,9]
I want new numpy array Z that have Z1, Z2, Z3 as array like:
    Z = [[1,2,3],[4,5],[6,7,8,9]
    print(type(Z),type(Z[0]))
    >>> <class 'numpy.ndarray'> <class 'numpy.ndarray'>
I used np.append, hstack, vstack, insert, concatenate ...but all I failed.
There is only 2 case:
    Z = [1,2,3,4,5,6,7,8,9]
or ERROR
so I made a list Z first, and append list Z1, Z2, Z3 and then convert list Z into numpy array Z.
BUT
    Z = [[1,2,3],[4,5],[6,7,8,9]]
    print(type(Z),type(Z[0]))
    >>> <class 'numpy.ndarray'> <class 'list'> 
I want to do not use 'while' or 'for'. Help me please..