Tensorflow学习笔记
  • Introduction
  • Tensorflow基础框架
    • 处理结构
    • 例子2
    • Session 会话控制
    • Variable 变量
    • Placeholder 传入值
    • 激励函数
  • 建造第一个神经网络
    • 添加层 def add_layer()
    • 建造神经网络
    • 结果可视化
    • Optimizer
    • Daterset
  • 可视化好助手Tensorboard
    • Tensorboard可视化好帮手1
    • Tensorboard 可视化好帮手 2
  • 高阶内容
    • Classification 分类学习
    • Dropout 解决 overfitting
    • CNN 卷积神经网络 1
    • CNN 卷积神经网络 2
    • Saver 保存读取
    • RNN LSTM 循环神经网络 (分类例子)
    • RNN LSTM (回归例子)
    • RNN LSTM (回归例子可视化)
    • 自编码Autoencoder(非监督学习)
    • scope 命名方法
    • Batch Normalization 批标准化
    • 用 Tensorflow 可视化梯度下降
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  1. 建造第一个神经网络

Daterset

import tensorflow as tf
import numpy as np
from tensorflow.contrib.data import Dataset
import matplotlib.pyplot as plt

# load your data or create your data in here
npx = np.random.uniform(-1, 1, (1000, 1))                           # x data
npy = np.power(npx, 2) + np.random.normal(0, 0.1, size=npx.shape)   # y data
npx_train, npx_test = np.split(npx, [800])                          # training and test data
npy_train, npy_test = np.split(npy, [800])

# use placeholder, later you may need different data, pass the different data into placeholder
tfx = tf.placeholder(npx_train.dtype, npx_train.shape)
tfy = tf.placeholder(npy_train.dtype, npy_train.shape)

# create dataloader
dataset = tf.data.Dataset.from_tensor_slices((tfx, tfy))
dataset = dataset.shuffle(buffer_size=1000)   # choose data randomly from this buffer
dataset = dataset.batch(32)                   # batch size you will use
dataset = dataset.repeat(3)                   # repeat for 3 epochs
iterator = dataset.make_initializable_iterator()  # later we have to initialize this one

# your network
bx, by = iterator.get_next()                  # use batch to update
l1 = tf.layers.dense(bx, 10, tf.nn.relu)
out = tf.layers.dense(l1, npy.shape[1])
loss = tf.losses.mean_squared_error(by, out)
train = tf.train.GradientDescentOptimizer(0.1).minimize(loss)

sess = tf.Session()
# need to initialize the iterator in this case
sess.run([iterator.initializer, tf.global_variables_initializer()], feed_dict={tfx: npx_train, tfy: npy_train})
train_losses,test_losses=[],[]
for step in range(201):
    try:
        _, trainl = sess.run([train, loss])                       # train

        # if step % 10 == 0:
        testl = sess.run(loss, {bx: npx_test, by: npy_test})    # test
        train_losses.append(trainl)
        test_losses.append(testl)
          # print('step: %i/200' % step, '|train loss:', trainl, '|test loss:', testl)
    except tf.errors.OutOfRangeError:     # if training takes more than 3 epochs, training will be stopped
        print('Finish the last epoch.')
        break
print(step)
plt.plot(list(range(step)),train_losses,color='r',label='train loss')
plt.plot(list(range(step)),test_losses,color='b',label='test loss')
plt.legend(loc='best')
plt.show()
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