tensorflow实现KNN识别MNIST

__author__ = 'freedom' 
import tensorflow as tf 
import numpy as np 
 
def loadMNIST(): 
 from tensorflow.examples.tutorials.mnist import input_data 
 mnist = input_data.read_data_sets('MNIST_data',one_hot=True) 
 return mnist 
def KNN(mnist): 
 train_x,train_y = mnist.train.next_batch(5000) 
 test_x,test_y = mnist.train.next_batch(200) 
 
 xtr = tf.placeholder(tf.float32,[None,784]) 
 xte = tf.placeholder(tf.float32,[784]) 
 distance = tf.sqrt(tf.reduce_sum(tf.pow(tf.add(xtr,tf.neg(xte)),2),reduction_indices=1)) 
 
 pred = tf.argmin(distance,0) 
 
 init = tf.initialize_all_variables() 
 
 sess = tf.Session() 
 sess.run(init) 
 
 right = 0 
 for i in range(200): 
  ansIndex = sess.run(pred,{xtr:train_x,xte:test_x[i,:]}) 
  print 'prediction is ',np.argmax(train_y[ansIndex]) 
  print 'true value is ',np.argmax(test_y[i]) 
  if np.argmax(test_y[i]) == np.argmax(train_y[ansIndex]): 
   right += 1.0 
 accracy = right/200.0 
 print accracy 
 
if __name__ == "__main__": 
 mnist = loadMNIST() 
 KNN(mnist)