init empty numpy array with shape code example

Example 1: numpy empty array

import numpy as np

n = 2
X = np.empty(shape=[0, n])

for i in range(5):
    for j  in range(2):
        X = np.append(X, [[i, j]], axis=0)

print X

Example 2: declare empty array of complex type python

numpy.empty(shape, dtype=float, order='C')

Example 3: create empty numpy array without shape

a = []
    for x in y:
        a.append(x)
    a = np.array(a)