python
1# リスト 4-5-(1)
2import numpy as np
3import matplotlib.pyplot as plt
4from mpl_toolkits.mplot3d import axes3d
5%matplotlib inline
6
7# ガウス関数  -----------------------------
8def gauss(x, mu, sigma):
9    N, D = x.shape
10    c1 = 1 / (2 * np.pi)**(D / 2)
11    c2 = 1 / (np.linalg.det(sigma)**(1 / 2))
12    inv_sigma = np.linalg.inv(sigma)
13    c3 = x - mu
14    c4 = np.dot(c3, inv_sigma)
15    c5 = np.zeros(N)
16    for d in range(D):
17        c5 = c5 + c4[:, d] * c3[:, d]
18    p = c1 * c2 * np.exp(-c5 / 2)
19    return p
20# リスト 4-5-(2)
21x = np.array([[1, 2], [2, 1], [3, 4]])
22mu = np.array([1, 2])
23sigma = np.array([[1, 0], [0, 1]])
24print(gauss(x, mu, sigma))
25# リスト 4-5-(3)
26X_range0=[-3, 3]
27X_range1=[-3, 3]
28
29# 等高線表示 --------------------------------
30def show_contour_gauss(mu, sig):
31    xn = 40  # 等高線表示の解像度
32    x0 = np.linspace(X_range0[0], X_range0[1], xn)
33    x1 = np.linspace(X_range1[0], X_range1[1], xn)
34    xx0, xx1 = np.meshgrid(x0, x1)
35    x = np.c_[np.reshape(xx0, xn * xn, 1), np.reshape(xx1, xn * xn, 1)]
36    f = gauss(x, mu, sig)
37    f = f.reshape(xn, xn)
38    f = f.T
39    cont = plt.contour(xx0, xx1, f, 15, colors='k')
40    plt.grid(True)
41    
42# ３D 表示 ----------------------------------
43def show3d_gauss(ax, mu, sig):
44    xn = 40  # 等高線表示の解像度
45    x0 = np.linspace(X_range0[0], X_range0[1], xn)
46    x1 = np.linspace(X_range1[0], X_range1[1], xn)
47    xx0, xx1 = np.meshgrid(x0, x1)
48    x = np.c_[np.reshape(xx0, xn * xn, 1), np.reshape(xx1, xn * xn, 1)]
49    f = gauss(x, mu, sig)
50    f = f.reshape(xn, xn)
51    f = f.T
52    ax.plot_surface(xx0, xx1, f, 
53                    rstride=2, cstride=2, alpha=0.3, 
54                    color='blue', edgecolor='black')
55    
56# メイン -----------------------------------
57mu = np.array([1, 0.5])            # (A)
58sigma = np.array([[2, 1], [1, 1]]) # (B)
59Fig = plt.figure(1, figsize=(7, 3))
60Fig.add_subplot(1, 2, 1)
61show_contour_gauss(mu, sigma)
62plt.xlim(X_range0)
63plt.ylim(X_range1)
64plt.xlabel('$x_0$', fontsize=14)
65plt.ylabel('$x_1$', fontsize=14)
66Ax = Fig.add_subplot(1, 2, 2, projection='3d')
67show3d_gauss(Ax, mu, sigma)
68Ax.set_zticks([0.05, 0.10])
69Ax.set_xlabel('$x_0$', fontsize=14)
70Ax.set_ylabel('$x_1$', fontsize=14)
71Ax.view_init(40, -100)
72plt.show()

#-----------------------------------------------

実行すると以下のようなエラーが出てその原因が分かりません。

ValueError Traceback (most recent call last)
<ipython-input-42-074e12a40b6e> in <module>
35 Fig = plt.figure(1, figsize=(7, 3))
36 Fig.add_subplot(1, 2, 1)
---> 37 show_contour_gauss(mu, sigma)
38 plt.xlim(X_range0)
39 plt.ylim(X_range1)

<ipython-input-42-074e12a40b6e> in show_contour_gauss(mu, sig)
9 x1 = np.linspace(X_range1[0], X_range1[1], xn)
10 xx0, xx1 = np.meshgrid(x0, x1)
---> 11 x = np.c_[np.reshape(xx0, xn * xn, 1), np.reshape(xx1, xn * xn, 1)]
12 f = gauss(x, mu, sig)
13 f = f.reshape(xn, xn)

<array_function internals> in reshape(*args, **kwargs)

~\anaconda3\lib\site-packages\numpy\core\fromnumeric.py in reshape(a, newshape, order)
299 [5, 6]])
300 """
--> 301 return _wrapfunc(a, 'reshape', newshape, order=order)
302
303

~\anaconda3\lib\site-packages\numpy\core\fromnumeric.py in _wrapfunc(obj, method, *args, **kwds)
59
60 try:
---> 61 return bound(*args, **kwds)
62 except TypeError:
63 # A TypeError occurs if the object does have such a method in its

ValueError: Non-string object detected for the array ordering. Please pass in 'C', 'F', 'A', or 'K' instead