-- coding: utf-8 --

import numpy as np

①

a = np.arange(20).reshape(4, 5) a[:, [0, 1]] = a[:, [1, 0]] a[[0, 1], :] = a[[1, 0], :]

②

b = np.zeros((8, 8), dtype=int) b[1::2, ::2] = 1 b[::2, 1::2] = 1

③

c = np.zeros((10, 10), dtype=int) c[0, :] = 1 c[-1, :] = 1 c[:, 0] = 1 c[:, -1] = 1

④

d = np.random.randint(1, 10, size=(5, 5)) d = d[d[:, 2].argsort()]

⑤

e = np.array([1, 2, 3, 4, 5]) e = np.hstack((e[:, np.newaxis], np.zeros((5, 3), dtype=int))) e = e.reshape(-1) e = e[:-3]

print(a) print(b) print(c) print(d) print(e)