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2019 iT 邦幫忙鐵人賽

DAY 21
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今天依然來用莫凡python教學網站來學習,跟著流程做一遍~

把先前的例題用tensorflow的結構重寫一遍,code的下載位置

from __future__ import print_function
import tensorflow as tf
import numpy as np
import matplotlib.pyplot as plt

def add_layer(inputs, in_size, out_size, activation_function=None):
    Weights = tf.Variable(tf.random_normal([in_size, out_size]))
    biases = tf.Variable(tf.zeros([1, out_size]) + 0.1)
    Wx_plus_b = tf.matmul(inputs, Weights) + biases
    if activation_function is None:
        outputs = Wx_plus_b
    else:
        outputs = activation_function(Wx_plus_b)
    return outputs

# Make up some real data
x_data = np.linspace(-1, 1, 300)[:, np.newaxis]
noise = np.random.normal(0, 0.05, x_data.shape)
y_data = np.square(x_data) - 0.5 + noise

##plt.scatter(x_data, y_data)
##plt.show()

# define placeholder for inputs to network
xs = tf.placeholder(tf.float32, [None, 1])
ys = tf.placeholder(tf.float32, [None, 1])
# add hidden layer
l1 = add_layer(xs, 1, 10, activation_function=tf.nn.relu)
# add output layer
prediction = add_layer(l1, 10, 1, activation_function=None)

# the error between prediction and real data
loss = tf.reduce_mean(tf.reduce_sum(tf.square(ys-prediction), reduction_indices=[1]))
train_step = tf.train.GradientDescentOptimizer(0.1).minimize(loss)
# important step
sess = tf.Session()
# tf.initialize_all_variables() no long valid from
# 2017-03-02 if using tensorflow >= 0.12
if int((tf.__version__).split('.')[1]) < 12 and int((tf.__version__).split('.')[0]) < 1:
    init = tf.initialize_all_variables()
else:
    init = tf.global_variables_initializer()
sess.run(init)

接下來先畫圖

# plot the real data
fig = plt.figure()
ax = fig.add_subplot(1,1,1)
ax.scatter(x_data, y_data)
plt.ion()  #讓圖可以繼續畫新的
plt.show()
for i in range(1000):
    # training
    sess.run(train_step, feed_dict={xs: x_data, ys: y_data})
    if i % 50 == 0:
        # to visualize the result and improvement
        try:                                   
            ax.lines.remove(lines[0])  #避免太多線畫一起
        except Exception:     # 一開始還沒劃線先用pass除錯
            pass
        prediction_value = sess.run(prediction, feed_dict={xs: x_data})
        # plot the prediction
        lines = ax.plot(x_data, prediction_value, 'r-', lw=5)
        plt.pause(1)

最後使用terminal來執行輸入 python xxx.py(檔案名稱),就可以跑出如下動圖了

一步一步改修正自己的路線減少誤差~~

https://ithelp.ithome.com.tw/upload/images/20181104/20112303KxF7OmAUxJ.pnghttps://ithelp.ithome.com.tw/upload/images/20181104/20112303lNhCfKek99.pnghttps://ithelp.ithome.com.tw/upload/images/20181104/20112303kaMF73OFTa.png

明天再來練習其他的例子/images/emoticon/emoticon10.gif


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[第二十天]Tensorflow 練習3
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[第22天] Tensorflow 練習5
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Machine Learning 學習筆記30

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