import math
import matplotlib.pyplot as plt
import numpy as np
def sigmoid(x):
 a = []
 for i in x:
    a.append(1/(1+math.exp(-i)))
 return a
def tanh(x, derivative=False):
    if (derivative == True):
        return (1 - (x ** 2))
    else:
        return np.tanh(x)
def re(x):
    b = []
    for i in x:
        if i < 0:
            b.append(0)
        else:
            b.append(i)
    return b
def lr(x):
    b = []
    for i in x:
        if i < 0:
            b.append(i / 10)
        else:
            b.append(i)
    return b
x = np.arange(-9., 9., 0.1)
sig = sigmoid(x)
tanh = tanh(x)
relu = re(x)
leaky_relu = lr(x)
line_1, = plt.plot(x,sig, label='Sigmoid')
line_2, = plt.plot(x,tanh, label='Tanh')
line_3, = plt.plot(x,relu, label='ReLU')
line_4, = plt.plot(x,leaky_relu, label='Leaky ReLU')
plt.legend(handles=[line_1, line_2, line_3, line_4])
plt.axhline(y=0, color='k')
plt.axvline(x=0, color='k')
plt.show()