numpy数组取值 [:3] 和 [:,3]区别

a = np.array([[random.randint(10, 99) for i in range(5)] for j in range(5)])
print(a, '\n\n')
print(a[:3])
print('\n\n', a[:, 3])

[[90 78 57 85 76]
 [10 10 68 73 82]
 [22 92 97 23 91]
 [66 10 61 33 52]
 [32 91 87 53 93]] 

-------------------------------------------
[[90 78 57 85 76]
 [10 10 68 73 82]
 [22 92 97 23 91]]

-------------------------------------------
 [85 73 23 33 53]