2017-01-15 46 views
0

我一直在遵循tensorflow教程。我導入了MNIST數據集並運行了2層卷積神經網絡的代碼。培訓花了將近45分鐘。我想通過丟棄一些數據來減少訓練數據。我怎麼做? 下面的代碼:分裂MNIST數據張量流

import tensorflow as tf 
import numpy as np 
from tensorflow.examples.tutorials.mnist import input_data 

mnist = input_data.read_data_sets('MNIST_data', one_hot=True) 

def weight_variable(shape): 
    initial = tf.truncated_normal(shape, stddev=0.1) 
    return tf.Variable(initial) 

def bias_variable(shape): 
    initial = tf.constant(0.1, shape=shape) 
    return tf.Variable(initial) 


def conv2d(x, W): 
    return tf.nn.conv2d(x, W, strides=[1, 1, 1, 1], padding='SAME') 

def max_pool_2x2(x): 
    return tf.nn.max_pool(x, ksize=[1, 2, 2, 1],strides=[1, 2, 2, 1], padding='SAME') 

x = tf.placeholder(tf.float32, shape=[None, 784]) 
y_ = tf.placeholder(tf.float32, [None, 10]) 


W_conv1 = weight_variable([5, 5, 1, 32]) 
b_conv1 = bias_variable([32]) 

x_image = tf.reshape(x, [-1,28,28,1]) 

h_conv1 = tf.nn.relu(conv2d(x_image, W_conv1) + b_conv1) 
h_pool1 = max_pool_2x2(h_conv1) 

W_conv2 = weight_variable([5, 5, 32, 64]) 
b_conv2 = bias_variable([64]) 

h_conv2 = tf.nn.relu(conv2d(h_pool1, W_conv2) + b_conv2) 
h_pool2 = max_pool_2x2(h_conv2) 

W_fc1 = weight_variable([7 * 7 * 64, 1024]) 
b_fc1 = bias_variable([1024]) 

h_pool2_flat = tf.reshape(h_pool2, [-1, 7*7*64]) 
h_fc1 = tf.nn.relu(tf.matmul(h_pool2_flat, W_fc1) + b_fc1) 

keep_prob = tf.placeholder(tf.float32) 
h_fc1_drop = tf.nn.dropout(h_fc1, keep_prob) 

W_fc2 = weight_variable([1024, 10]) 
b_fc2 = bias_variable([10]) 

y_conv = tf.matmul(h_fc1_drop, W_fc2) + b_fc2 
cross_entropy = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(y_conv, y_)) 
train_step = tf.train.AdamOptimizer(1e-4).minimize(cross_entropy) 
correct_prediction = tf.equal(tf.argmax(y_conv,1), tf.argmax(y_,1)) 
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32)) 
sess = tf.Session() 
sess.run(tf.initialize_all_variables()) 

for i in range(20000): 
    batch = mnist.train.next_batch(50) 
    if i%100 == 0: 
    train_accuracy = accuracy.eval(session=sess,feed_dict={x:batch[0], y_: batch[1], keep_prob: 1.0}) 
    print("step %d, training accuracy %g"%(i, train_accuracy)) 
    train_step.run(session=sess,feed_dict={x: batch[0], y_: batch[1], keep_prob: 0.5}) 

print("test accuracy %g"%accuracy.eval(session=sess,feed_dict={x: np.split(mnist.test.images,5)[0], y_: np.split(mnist.test.labels,5)[0], keep_prob: 1.0})) 

我砍倒測試數據的大小,因爲它是一個numpy的陣列。我如何對訓練數據做同樣的事情?

+0

您可以在此處找到已解碼的MNIST數據集版本:http://mnist-decoded.000webhostapp.com/ – SomethingSomething

回答

1

削減你的訓練樣本不會以任何好的方式幫助你 - 只要你使用minibatches,它不會直接影響性能。作爲一個更好的選擇,您可以減少時代數量和/或提高學習速度。 在這種情況下減少數據採樣是一個非常糟糕的主意

0

只是一個問題 - 我們正在談論這個代碼`https://www.tensorflow.org/tutorials/mnist/pros/ ???

所以,如果這需要45分鐘,我想你是在CPU上運行 - 你應該考慮使用GPU。我使用Tesla K 80 GPU在Azure VM N系列中測試代碼,並在4分鐘內完成代碼