def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he"):
"""
Implements a three-layer neural network: LINEAR->RELU->LINEAR->RELU->LINEAR->SIGMOID.
Arguments:
X -- input data, of shape (2, number of examples)
Y -- true "label" vector (containing 0 for red dots; 1 for blue dots), of shape (1, number of examples)
learning_rate -- learning rate for gradient descent
num_iterations -- number of iterations to run gradient descent
print_cost -- if True, print the cost every 1000 iterations
initialization -- flag to choose which initialization to use ("zeros","random" or "he")
Returns:
parameters -- parameters learnt by the model
"""
grads = {}
costs = [] # to keep track of the loss
m = X.shape[1] # number of examples
layers_dims = [X.shape[0], 10, 5, 1]
# Initialize parameters dictionary.
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
# Loop (gradient descent)
for i in range(0, num_iterations):
# Forward propagation: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID.
a3, cache = forward_propagation(X, parameters)
cost = compute_loss(a3, Y)
grads = backward_propagation(X, Y, cache)
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# plot the loss
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="zeros"):
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
for i in range(0, num_iterations):
a3, cache = forward_propagation(X, parameters)
cost = compute_loss(a3, Y)
grads = backward_propagation(X, Y, cache)
paramters = update_parameters(parameters, grads, learning_rate)
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X, Y, alpha=0.005, loops=5000, init_method='he'):
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
# inintial params
if init_method == 'zeros':
params = init_zeros(layers_dims)
elif init_method == 'random':
params = init_random(layers_dims)
elif init_method == 'he':
params = init_he(layers_dims)
else:
print('Error: unexcepted init_method!')
# start train
for i in range(loops):
a3, cache = init_utils.forward_propagation(X, params)
cost = init_utils.compute_loss(a3, Y)
costs.append(cost)
grads = init_utils.backward_propagation(X, Y, cache)
params = init_utils.update_parameters(params, grads, alpha)
if (i + 1) % 100 == 0:
print(f'No.{i+1} iteration\'s loss: {cost}')
plt.plot(costs)
plt.xlabel('step')
plt.ylabel('loss')
plt.title('loss circle')
plt.show()
return params
def model(X, Y, learning_rate = 0.01, num_iterations = 15000, print_cost = True, initialization = "he"):
"""
Implements a three-layer neural network: LINEAR->RELU->LINEAR->RELU->LINEAR->SIGMOID.
Arguments:
X -- input data, of shape (2, number of examples)
Y -- true "label" vector (containing 0 for red dots; 1 for blue dots), of shape (1, number of examples)
learning_rate -- learning rate for gradient descent
num_iterations -- number of iterations to run gradient descent
print_cost -- if True, print the cost every 1000 iterations
initialization -- flag to choose which initialization to use ("zeros","random" or "he")
Returns:
parameters -- parameters learnt by the model
"""
grads = {}
costs = [] # to keep track of the loss
m = X.shape[1] # number of examples
layers_dims = [X.shape[0], 10, 5, 1]
# Initialize parameters dictionary.
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
# Loop (gradient descent)
for i in range(0, num_iterations):
# Forward propagation: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID.
a3, cache = forward_propagation(X, parameters)
# Loss
cost = compute_loss(a3, Y)
# Backward propagation.
grads = backward_propagation(X, Y, cache)
# Update parameters.
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# plot the loss
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization='he',
is_plot=True):
"""
实现一个三层网络:LINEAR->RELU->LINEAR->RELU->LINEAR->SIGMOID
参数:
X -输入的数据,维度(2,训练/测试的数量)
Y -标签 [0|1],维度(1,训练/测试的数量)
learning_rate -学习速率
num_iterations -迭代次数
print_cost -是否打印成本值,每迭代1000次打印一次
initialization -字符串类型,[zeros|random|he]
is_plot -是否绘制梯度下降的曲线图
返回:
parameters -学习后的参数
"""
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
else:
print("Fault initializtion argument! quit")
exit
for i in range(0, num_iterations):
a3, cache = init_utils.forward_propagation(X, parameters)
cost = init_utils.compute_loss(a3, Y)
grads = init_utils.backward_propagation(X, Y, cache)
parameters = init_utils.update_parameters(parameters, grads,
learning_rate)
if i % 1000 == 0:
costs.append(cost)
if print_cost:
print("number times" + str(i) + " cost is " + str(cost))
if is_plot:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations(per hundreds)')
plt.title('learing_rate:' + str(learning_rate))
plt.show()
return parameters
def model(X, Y, learning_rate = 0.01, num_iterations = 15000, print_cost = True, initialization = "he"):
"""
实现一个 3 层的神经网络: LINEAR->RELU->LINEAR->RELU->LINEAR->SIGMOID.
:param X: 输入数据, of shape (2, number of examples)
:param Y: 正确的标签向量 (containing 0 for red dots; 1 for blue dots), of shape (1, number of examples)
:param learning_rate: 梯度下降的学习率
:param num_iterations: 梯度下降的迭代次数
:param print_cost: if True, print the cost every 1000 iterations
:param initialization: string, 决定要使用的初始化方法 ("zeros","random" or "he")
:return parameters: 神经网络学习到的参数
"""
grads = {}
costs = [] # to keep track of the loss
m = X.shape[1] # number of examples
layers_dims = [X.shape[0], 10, 5, 1]
# 初始化参数字典
if initialization == "zeros": # 0 初始化
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random": # 随机初始化成较大的权重
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he": # 随机初始化成较小的权重，规模依据 paper by He et al., 2015.
parameters = initialize_parameters_he(layers_dims)
# 梯度下降法迭代
for i in range(0, num_iterations):
# 前向传播: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID.
a3, cache = forward_propagation(X, parameters)
# 计算损失值
cost = compute_loss(a3, Y)
# 后向传播
grads = backward_propagation(X, Y, cache)
# 更新参数
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# 绘制成本曲线（cost 值随着迭代的变化）
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization='he'):
"""
Implements a three-layer neural network: LINEAR->RELU->LINEAR->RELU->LINEAR->SIGMOID.
Arguments:
X -- input data, of shape (2, number of examples)
Y -- true "label" vector (containing 0 for red dots; 1 for blue dots), of shape (1, number of examples)
learning_rate -- learning rate for gradient descent
num_iterations -- number of iterations to run gradient descent
print_cost -- if True, print the cost every 1000 iterations
initialization -- flag to choose which initialization to use ("zeros","random" or "he")
Returns:
parameters -- parameters learnt by the model
"""
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
if initialization == 'zeros':
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == 'random':
parameters = initialize_parameters_random(layers_dims)
elif initialization == 'he':
parameters = initialize_parameters_he(layers_dims)
for i in range(num_iterations):
A3, cache = forward_propagation(X, parameters)
cost = compute_loss(A3, Y)
costs.append(cost)
if i % 100 == 0 and print_cost:
print('Cost at iteration {} is {}'.format(i, cost))
grads = backward_propagation(X, Y, cache)
parameters = update_parameters(parameters, grads, learning_rate)
# plot the cost
plt.plot(costs)
plt.xscale('linear')
plt.xlabel('iterations (per hundreds)')
plt.ylabel('Costs')
plt.title('learning rate =' + str(learning_rate))
plt.show()
return parameters
def model(X, Y, learning_rate = 0.01, num_iterations = 15000, print_cost = True, initialization = "he", is_plot = True):
"""
实现一个三层的神经网络：ReLU->ReLU->Sigmoid
:param X:输入数据,维度(2,要训练/测试的数量)
:param Y:标签,维度(1,对应输入数据的数量)
:param learning_rate:学习率
:param num_iterations:迭代次数
:param print_cost:是否打印成本值
:param initialization:权重矩阵初始化方法
:param is_plot:是否绘制梯度下降的曲线图
:return:
parameters:更新之后的参数
"""
parameters = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
# 选择初始化参数类型
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
for i in range(num_iterations):
# 前向传播
A3, cache = init_utils.forward_propagation(X, parameters)
# 计算成本
cost = init_utils.compute_loss(A3, Y)
if i % 1000 == 0:
costs.append(cost)
if print_cost:
print(f'第{i}次迭代,成本值为:{cost}')
# 反向传播
grads = init_utils.backward_propagation(X, Y, cache)
# 更新参数
parameters = init_utils.update_parameters(parameters, grads, learning_rate)
if is_plot:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he",
is_plot=True):
grads = {} # 这表示一个字典
costs = [] # 这表示一个矩阵
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
else:
print("错误的初始化参数！退出程序")
exit
for i in range(0, num_iterations):
a3, cache = init_utils.forward_propagation(X, parameters)
#计算成本
cost = init_utils.compute_loss(a3, Y)
#反向传播
grads = init_utils.backward_propagation(X, Y, cache)
#更新参数
parameters = init_utils.update_parameters(parameters, grads,
learning_rate)
#记录成本
if i % 1000 == 0:
costs.append(cost)
# 打印成本
if print_cost:
print("第" + str(i) + "次迭代，成本为：" + str(cost))
if is_plot:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iteration (per hundreds)')
plt.title("learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he",
is_plot=True):
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
# 初始化参数的类型
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
else:
print("初始化参数错误，程序退出")
exit
# 开始学习
for i in range(0, num_iterations):
# 前向传播
a3, cache = init_utils.forward_propagation(X, parameters)
# 计算损失
cost = init_utils.compute_loss(a3, Y)
# 反向传播
grads = init_utils.backward_propagation(X, Y, cache)
# 更新参数
parameters = init_utils.update_parameters(parameters, grads,
learning_rate)
# 记录成本
if i % 100 == 0:
costs.append(cost)
if print_cost:
print("第" + str(i) + "次迭代，成本值为" + str(cost))
# 绘制成本曲线
if is_plot:
plt.plot(costs)
plt.xlabel('iteration(per 100)')
plt.ylabel('cost J')
plt.title('learning_rate=' + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he"):
grads = {}
costs = [] # To keep track of the loss
m = X.shape[1] # Number of examples
layers_dims = [X.shape[0], 10, 5, 1]
# Initialize parameters dictionary
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
# Loop (gradient descent)
for i in range(0, num_iterations):
# Forward propagation: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID
a3, cache = forward_propagation(X, parameters)
# Loss
cost = compute_loss(a3, Y)
# Backward propagation
grads = backward_propagation(X, Y, cache)
# Update parameters
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# Plot the loss
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he",
is_polt=True):
losses = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
# 选择初始化参数的类型
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
for i in range(num_iterations):
# 前向传播
a3, cache = init_utils.forward_propagation(X, parameters)
# 计算Loss
loss = init_utils.compute_loss(a3, Y)
# 反向传播
gradients = init_utils.backward_propagation(X, Y, cache)
#更新权重
parameters = init_utils.update_parameters(parameters, gradients,
learning_rate)
if i % 1000 == 0:
losses.append(loss)
# 打印成本
if print_cost:
print("第" + str(i) + "次迭代，成本值为：" + str(loss))
# 学习完毕，绘制成本曲线
if is_polt:
plt.plot(losses)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
# 返回学习完毕后的参数
return parameters
def ini_model(X,
Y,
layer_dimension,
initialize_method,
learning_rate,
num_iteration=15000):
if initialize_method == 'zero':
parameters = zero_initialization(layer_dimension)
if initialize_method == 'random':
parameters = random_initialization(layer_dimension)
if initialize_method == 'he':
parameters = he_initialization(layer_dimension)
for i in range(0, num_iteration):
A3, cache = forward_propagation(X, parameters)
grads = backward_propagation(X, Y, cache)
parameters = update_parameters(parameters, grads, learning_rate)
cost = compute_loss(A3, Y)
if i % 1000 == 0:
print(f'cost after iteration {i}:{cost}')
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he"):
costs = [] # to keep track of the loss
layers_dims = [X.shape[0], 10, 5, 1]
parameters = {}
if initialization == "random":
parameters = bad_initialization_relu_act_fn(layers_dims)
elif initialization == "he":
parameters = good_initialization_relu_act_fn(layers_dims)
# Loop (gradient descent)
for i in range(0, num_iterations):
# Forward propagation: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID.
a3, cache = forward_propagation(X, parameters)
# Loss
cost = compute_loss(a3, Y)
# Backward propagation.
grads = backward_propagation(X, Y, cache)
# Update parameters.
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# plot the loss
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
init="he",
is_plot=True):
grads = {}
costs = []
m = X.shape[1]
layer_dims = [X.shape[0], 10, 5, 1]
if init == "zeros":
params = init_params_zeros(layer_dims)
elif init == "random":
params = init_params_random(layer_dims)
elif init == "he":
params = init_params_he(layer_dims)
else:
print("Wrong init option!")
exit
for i in range(0, num_iterations):
a3, cache = init_utils.forward_propagation(X, params)
cost = init_utils.compute_loss(a3, Y)
grads = init_utils.backward_propagation(X, Y, cache)
params = init_utils.update_parameters(params, grads, learning_rate)
if i % 1000 == 0:
costs.append(cost)
if print_cost:
print("Iteration " + str(i) + " Cost:" + str(cost))
if is_plot:
plt.plot(costs)
plt.ylabel("cost")
plt.xlabel("#iterations")
plt.title("Learning rate = " + str(learning_rate))
plt.show()
return params
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he"):
"""
implements a three-layer neural network:
linear -> relu -> linear -> relu -> linear -> sigmoid
arguments:
X -- input data, shape(2,number of examples)
Y -- true label vector
learning_rate -- learning rate for gradient descent
num_iterations -- number of iterations to run gradient descent
print_cost -- true,print the cost every 1000 iterations
returns:
parameters -- parameters learnt by the model
"""
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
#initialize parameters dictionary
if initialization == 'zeros':
print('init zeros')
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == 'random':
print('init random')
parameters = initialize_parameters_random(layers_dims)
elif initialization == 'he':
print('init he')
parameters = initialize_parameters_he(layers_dims)
print("w1 = ", parameters["W1"])
#loop
for i in range(0, num_iterations):
#forward
a3, cache = forward_propagation(X, parameters)
#loss
cost = compute_loss(a3, Y)
#backwawrd
grads = backward_propagation(X, Y, cache)
#update parameters
parameters = update_parameters(parameters, grads, learning_rate)
if print_cost and i % 1000 == 0:
print('cost after iteration{}:{}'.format(i, cost))
costs.append(cost)
plt.figure("2")
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations(per hundreds)')
plt.title('Learning rate = ' + str(learning_rate))
plt.show()
return parameters
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
# Loop (gradient descent)
for i in range(0, num_iterations):
# Forward propagation: LINEAR -> RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID.
a3, cache = forward_propagation(X, parameters)
# Loss
cost = compute_loss(a3, Y)
# Backward propagation.
grads = backward_propagation(X, Y, cache)
# Update parameters.
parameters = update_parameters(parameters, grads, learning_rate)
# Print the loss every 1000 iterations
if print_cost and i % 1000 == 0:
print("Cost after iteration {}: {}".format(i, cost))
costs.append(cost)
# plot the loss
plt.plot(costs)
plt.ylabel('cost')
def model(X,Y,learning_rate = 0.01,num_iterations = 15000,print_cost = True,initialization='he',is_polt = True):
'''
实现一个三层的神经网络:linear->relu->linear->relu->linear->sigmoid
:param X: 输入的数据,维度为(2,要训练/测试的数量)
:param Y: 标签,[0/1],维度为(1,对应的是输入的数据的标签)
:param learning_rate: 学习速率
:param num_iterations: 迭代的次数
:param print_cost: 是否打印成本值,每次迭代1000次打印一次
:param initialize: 字符串类型,初始化的类型['zero'|'random'|'he']
:param is_plot: 是否绘制梯度下降的曲线图
:return:
parameters -学习后的参数
'''
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0],10,5,1]
#选择初始化参数类型
if initialization == 'zeros':
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == 'random':
parameters = initialize_parameters_random(layers_dims)
elif initialization == 'he':
parameters = initialize_parameters_he(layers_dims)
else:
print('错误的初始化参数!程序退出')
exit
#开始学习
for i in range(0,num_iterations):
#前向传播
a3 ,cache = init_utils.forward_propagation(X,parameters)
#计算成本
cost = init_utils.compute_loss(a3,Y)
#反向传播
grads = init_utils.backward_propagation(X,Y,cache)
#更新参数
parameters = init_utils.update_parameters(parameters,grads,learning_rate)
#记录成本
if i%1000 == 0:
costs.append(cost)
#打印成本
if print_cost:
print('第'+str(i)+'次迭代,成本值为'+str(cost))
#学习完毕,绘制成本曲线
if is_polt:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations(per hundreds)')
plt.title('Learning rate ='+str(learning_rate))
plt.show()
#返回学习完毕后的参数
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization="he",
is_polt=True):
"""
实现一个三层的神经网络：LINEAR ->RELU -> LINEAR -> RELU -> LINEAR -> SIGMOID
参数：
X - 输入的数据，维度为(2, 要训练/测试的数量)
Y - 标签，【0 | 1】，维度为(1，对应的是输入的数据的标签)
learning_rate - 学习速率
num_iterations - 迭代的次数
print_cost - 是否打印成本值，每迭代1000次打印一次
initialization - 字符串类型，初始化的类型【"zeros" | "random" | "he"】
is_polt - 是否绘制梯度下降的曲线图
返回
parameters - 学习后的参数
"""
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
# 选择初始化参数的类型
if initialization == "zeros":
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == "random":
parameters = initialize_parameters_random(layers_dims)
elif initialization == "he":
parameters = initialize_parameters_he(layers_dims)
else:
print("错误的初始化参数！程序退出")
exit()
# 开始学习
for i in range(0, num_iterations):
# 前向传播
a3, cache = init_utils.forward_propagation(X, parameters)
# 计算成本
cost = init_utils.compute_loss(a3, Y)
# 反向传播
grads = init_utils.backward_propagation(X, Y, cache)
# 更新参数
parameters = init_utils.update_parameters(parameters, grads,
learning_rate)
# 记录成本
if i % 1000 == 0:
costs.append(cost)
# 打印成本
if print_cost:
print("第" + str(i) + "次迭代，成本值为：" + str(cost))
# 学习完毕，绘制成本曲线
if is_polt:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations (per hundreds)')
plt.title("Learning rate =" + str(learning_rate))
plt.show()
# 返回学习完毕后的参数
return parameters
def model(X,
Y,
learning_rate=0.01,
num_iterations=15000,
print_cost=True,
initialization='he',
is_polt=True):
'''
实现一个三层的神经网络:linear->relu->linear->relu->linear->sigmoid
:param X: 输入的数据,维度为(2,要训练/测试的数量)
:param Y: 标签,[0/1],维度为(1,对应的是输入的数据的标签)
:param learning_rate: 学习速率
:param num_iterations: 迭代的次数
:param print_cost: 是否打印成本值,每次迭代1000次打印一次
:param initialize: 字符串类型,初始化的类型['zero'|'random'|'he']
:param is_plot: 是否绘制梯度下降的曲线图
:return:
parameters -学习后的参数
'''
grads = {}
costs = []
m = X.shape[1]
layers_dims = [X.shape[0], 10, 5, 1]
#选择初始化参数类型
if initialization == 'zeros':
parameters = initialize_parameters_zeros(layers_dims)
elif initialization == 'random':
parameters = initialize_parameters_random(layers_dims)
elif initialization == 'he':
parameters = initialize_parameters_he(layers_dims)
else:
print('错误的初始化参数!程序退出')
exit
#开始学习
for i in range(0, num_iterations):
#前向传播
a3, cache = init_utils.forward_propagation(X, parameters)
#计算成本
cost = init_utils.compute_loss(a3, Y)
#反向传播
grads = init_utils.backward_propagation(X, Y, cache)
#更新参数
parameters = init_utils.update_parameters(parameters, grads,
learning_rate)
#记录成本
if i % 1000 == 0:
costs.append(cost)
#打印成本
if print_cost:
print('第' + str(i) + '次迭代,成本值为' + str(cost))
#学习完毕,绘制成本曲线
if is_polt:
plt.plot(costs)
plt.ylabel('cost')
plt.xlabel('iterations(per hundreds)')
plt.title('Learning rate =' + str(learning_rate))
plt.show()
#返回学习完毕后的参数
return parameters