1. # -*- coding:utf-8 -*-
    2. from matplotlib import pyplot as plt
    3. import numpy as np
    4. import mpl_toolkits.axisartist as axisartist
    7. def sigmoid(x):
    8.     return 1. / (1 + np.exp(-x))
    11. def tanh(x):
    12.     return (np.exp(x) - np.exp(-x)) / (np.exp(x) + np.exp(-x))
    15. def relu(x):
    16.     return np.where(x<0,0,x)
    19. def prelu(x):
    20.     return np.where(x<0,0.5*x,x)
    22. def plot_sigmoid():
    23.     x = np.arange(-10, 10, 0.1)
    24.     y = sigmoid(x)
    25.     fig = plt.figure()
    26.     # ax = fig.add_subplot(111)
    27.     ax = axisartist.Subplot(fig,111)
    28.     ax.spines['top'].set_color('none')
    29.     ax.spines['right'].set_color('none')
    30.     # ax.spines['bottom'].set_color('none')
    31.     # ax.spines['left'].set_color('none')
    32.     ax.axis['bottom'].set_axisline_style("-|>",size=1.5)
    33.     ax.spines['left'].set_position(('data', 0))
    34.     ax.plot(x, y)
    35.     plt.xlim([-10.05, 10.05])
    36.     plt.ylim([-0.02, 1.02])
    37.     plt.tight_layout()
    38.     plt.savefig("sigmoid.png")
    39.     plt.show()
    42. def plot_tanh():
    43.     x = np.arange(-10, 10, 0.1)
    44.     y = tanh(x)
    45.     fig = plt.figure()
    46.     ax = fig.add_subplot(111)
    47.     ax.spines['top'].set_color('none')
    48.     ax.spines['right'].set_color('none')
    49.     # ax.spines['bottom'].set_color('none')
    50.     # ax.spines['left'].set_color('none')
    51.     ax.spines['left'].set_position(('data', 0))
    52.     ax.spines['bottom'].set_position(('data', 0))
    53.     ax.plot(x, y)
    54.     plt.xlim([-10.05, 10.05])
    55.     plt.ylim([-1.02, 1.02])
    56.     ax.set_yticks([-1.0, -0.5, 0.5, 1.0])
    57.     ax.set_xticks([-10, -5, 5, 10])
    58.     plt.tight_layout()
    59.     plt.savefig("tanh.png")
    60.     plt.show()
    63. def plot_relu():
    64.     x = np.arange(-10, 10, 0.1)
    65.     y = relu(x)
    66.     fig = plt.figure()
    67.     ax = fig.add_subplot(111)
    68.     ax.spines['top'].set_color('none')
    69.     ax.spines['right'].set_color('none')
    70.     # ax.spines['bottom'].set_color('none')
    71.     # ax.spines['left'].set_color('none')
    72.     ax.spines['left'].set_position(('data', 0))
    73.     ax.plot(x, y)
    74.     plt.xlim([-10.05, 10.05])
    75.     plt.ylim([0, 10.02])
    76.     ax.set_yticks([2, 4, 6, 8, 10])
    77.     plt.tight_layout()
    78.     plt.savefig("relu.png")
    79.     plt.show()
    82. def plot_prelu():
    83.     x = np.arange(-10, 10, 0.1)
    84.     y = prelu(x)
    85.     fig = plt.figure()
    86.     ax = fig.add_subplot(111)
    87.     ax.spines['top'].set_color('none')
    88.     ax.spines['right'].set_color('none')
    89.     # ax.spines['bottom'].set_color('none')
    90.     # ax.spines['left'].set_color('none')
    91.     ax.spines['left'].set_position(('data', 0))
    92.     ax.spines['bottom'].set_position(('data', 0))
    93.     ax.plot(x, y)
    94.     plt.xticks([])
    95.     plt.yticks([])
    96.     plt.tight_layout()
    97.     plt.savefig("prelu.png")
    98.     plt.show()
    101. if __name__ == "__main__":
    102.     plot_sigmoid()
    103.     plot_tanh()
    104.     plot_relu()
    105.     plot_prelu()