import numpy as np
import matplotlib.pyplot as plt

from utils import sigmoid


# visualize sigmoid function

def sigmoid_visual():
    z = np.arange(-7, 7, 0.1)
    phi_z = sigmoid(z)
    plt.plot(z, phi_z)
    plt.axvline(0.0, color='k')
    plt.ylim(-0.1, 1.1)
    plt.xlabel('z')
    plt.ylabel('$\phi (z)$')

    plt.yticks([0.0, 0.5, 1.0])
    ax = plt.gca()
    ax.yaxis.grid(True)
    plt.tight_layout()
    plt.show()
