Question

我有一个两个numpy 1-D阵列： a 和 b 。

a 的形状（10，） b 具有形状（16，）。

我想让 a 具有形状（10,1）和 b 以使形状（16,1）与矩阵相乘，如下所示：np。 matmul（a，bT）。

如果成功，则应该产生（10,16）2-D阵列。有谁知道怎么做？

Answer 1

IIUC：

In [47]: a = np.arange(10)

In [48]: b = np.arange(16)

In [49]: a[:,None] * b
Out[49]:
array([[  0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
       [  0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,  15],
       [  0,   2,   4,   6,   8,  10,  12,  14,  16,  18,  20,  22,  24,  26,  28,  30],
       [  0,   3,   6,   9,  12,  15,  18,  21,  24,  27,  30,  33,  36,  39,  42,  45],
       [  0,   4,   8,  12,  16,  20,  24,  28,  32,  36,  40,  44,  48,  52,  56,  60],
       [  0,   5,  10,  15,  20,  25,  30,  35,  40,  45,  50,  55,  60,  65,  70,  75],
       [  0,   6,  12,  18,  24,  30,  36,  42,  48,  54,  60,  66,  72,  78,  84,  90],
       [  0,   7,  14,  21,  28,  35,  42,  49,  56,  63,  70,  77,  84,  91,  98, 105],
       [  0,   8,  16,  24,  32,  40,  48,  56,  64,  72,  80,  88,  96, 104, 112, 120],
       [  0,   9,  18,  27,  36,  45,  54,  63,  72,  81,  90,  99, 108, 117, 126, 135]])

Answer 2

您需要明确使用reshape。 b.T和b.transpose()对1D数组没有任何意义：

a = np.arange(10)
b = np.arange(16)
c = a.reshape(10, 1) @ b.reshape(1, 16)

正如预期的那样，

c.shape现在为(10, 16)。

Answer 3

您可以使用reshape方法。

import numpy as np

a = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]).reshape((10, 1))
b = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]).reshape((16, 1))
c = np.matmul(a, b.T)
print(c.shape)

矩阵乘以两个1-D numpy数组

3 个答案: