K近邻算法, TensorFlow示例

In [1]:

    

from __future__ import print_function
import numpy as np
import tensorflow as tf

# Import MNIST data, 准备MNIST数据输入
from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets("/tmp/data/", one_hot=True)


    

    




Extracting MNIST_data/train-images-idx3-ubyte.gz
Extracting MNIST_data/train-labels-idx1-ubyte.gz
Extracting MNIST_data/t10k-images-idx3-ubyte.gz
Extracting MNIST_data/t10k-labels-idx1-ubyte.gz

In [2]:

    

# In this example, we limit mnist data，限制候选比较数据的数目
Xtr, Ytr = mnist.train.next_batch(5000) #5000 for training (nn candidates)
Xte, Yte = mnist.test.next_batch(200) #200 for testing

# tf Graph Input，TensorFlow图模型的输入定义
xtr = tf.placeholder("float", [None, 784])
xte = tf.placeholder("float", [784])

# Nearest Neighbor calculation using L1 Distance，最小近邻算法的L1曼哈顿距离计算
# Calculate L1 Distance
distance = tf.reduce_sum(tf.abs(tf.add(xtr, tf.negative(xte))), reduction_indices=1)
# Prediction: Get min distance index (Nearest neighbor)，最小距离近邻的预测
pred = tf.arg_min(distance, 0)

accuracy = 0.

# Initialize the variables (i.e. assign their default value)，初始化所有参数
init = tf.global_variables_initializer()


    

In [3]:

    

# Start training
with tf.Session() as sess:
    sess.run(init)

    # loop over test data
    for i in range(len(Xte)):
        # Get nearest neighbor
        nn_index = sess.run(pred, feed_dict={xtr: Xtr, xte: Xte[i, :]})
        # Get nearest neighbor class label and compare it to its true label
        print "Test", i, "Prediction:", np.argmax(Ytr[nn_index]), \
            "True Class:", np.argmax(Yte[i])
        # Calculate accuracy
        if np.argmax(Ytr[nn_index]) == np.argmax(Yte[i]):
            accuracy += 1./len(Xte)
    print("Done!")
    print("Accuracy:", accuracy)


    

    




Test 0 Prediction: 7 True Class: 7
Test 1 Prediction: 2 True Class: 2
Test 2 Prediction: 1 True Class: 1
Test 3 Prediction: 0 True Class: 0
Test 4 Prediction: 4 True Class: 4
Test 5 Prediction: 1 True Class: 1
Test 6 Prediction: 4 True Class: 4
Test 7 Prediction: 9 True Class: 9
Test 8 Prediction: 8 True Class: 5
Test 9 Prediction: 9 True Class: 9
Test 10 Prediction: 0 True Class: 0
Test 11 Prediction: 0 True Class: 6
Test 12 Prediction: 9 True Class: 9
Test 13 Prediction: 0 True Class: 0
Test 14 Prediction: 1 True Class: 1
Test 15 Prediction: 5 True Class: 5
Test 16 Prediction: 4 True Class: 9
Test 17 Prediction: 7 True Class: 7
Test 18 Prediction: 3 True Class: 3
Test 19 Prediction: 4 True Class: 4
Test 20 Prediction: 9 True Class: 9
Test 21 Prediction: 6 True Class: 6
Test 22 Prediction: 6 True Class: 6
Test 23 Prediction: 5 True Class: 5
Test 24 Prediction: 4 True Class: 4
Test 25 Prediction: 0 True Class: 0
Test 26 Prediction: 7 True Class: 7
Test 27 Prediction: 4 True Class: 4
Test 28 Prediction: 0 True Class: 0
Test 29 Prediction: 1 True Class: 1
Test 30 Prediction: 3 True Class: 3
Test 31 Prediction: 1 True Class: 1
Test 32 Prediction: 3 True Class: 3
Test 33 Prediction: 4 True Class: 4
Test 34 Prediction: 7 True Class: 7
Test 35 Prediction: 2 True Class: 2
Test 36 Prediction: 7 True Class: 7
Test 37 Prediction: 1 True Class: 1
Test 38 Prediction: 2 True Class: 2
Test 39 Prediction: 1 True Class: 1
Test 40 Prediction: 1 True Class: 1
Test 41 Prediction: 7 True Class: 7
Test 42 Prediction: 4 True Class: 4
Test 43 Prediction: 1 True Class: 2
Test 44 Prediction: 3 True Class: 3
Test 45 Prediction: 5 True Class: 5
Test 46 Prediction: 1 True Class: 1
Test 47 Prediction: 2 True Class: 2
Test 48 Prediction: 4 True Class: 4
Test 49 Prediction: 4 True Class: 4
Test 50 Prediction: 6 True Class: 6
Test 51 Prediction: 3 True Class: 3
Test 52 Prediction: 5 True Class: 5
Test 53 Prediction: 5 True Class: 5
Test 54 Prediction: 6 True Class: 6
Test 55 Prediction: 0 True Class: 0
Test 56 Prediction: 4 True Class: 4
Test 57 Prediction: 1 True Class: 1
Test 58 Prediction: 9 True Class: 9
Test 59 Prediction: 5 True Class: 5
Test 60 Prediction: 7 True Class: 7
Test 61 Prediction: 8 True Class: 8
Test 62 Prediction: 9 True Class: 9
Test 63 Prediction: 3 True Class: 3
Test 64 Prediction: 7 True Class: 7
Test 65 Prediction: 4 True Class: 4
Test 66 Prediction: 6 True Class: 6
Test 67 Prediction: 4 True Class: 4
Test 68 Prediction: 3 True Class: 3
Test 69 Prediction: 0 True Class: 0
Test 70 Prediction: 7 True Class: 7
Test 71 Prediction: 0 True Class: 0
Test 72 Prediction: 2 True Class: 2
Test 73 Prediction: 7 True Class: 9
Test 74 Prediction: 1 True Class: 1
Test 75 Prediction: 7 True Class: 7
Test 76 Prediction: 3 True Class: 3
Test 77 Prediction: 7 True Class: 2
Test 78 Prediction: 9 True Class: 9
Test 79 Prediction: 7 True Class: 7
Test 80 Prediction: 7 True Class: 7
Test 81 Prediction: 6 True Class: 6
Test 82 Prediction: 2 True Class: 2
Test 83 Prediction: 7 True Class: 7
Test 84 Prediction: 8 True Class: 8
Test 85 Prediction: 4 True Class: 4
Test 86 Prediction: 7 True Class: 7
Test 87 Prediction: 3 True Class: 3
Test 88 Prediction: 6 True Class: 6
Test 89 Prediction: 1 True Class: 1
Test 90 Prediction: 3 True Class: 3
Test 91 Prediction: 6 True Class: 6
Test 92 Prediction: 9 True Class: 9
Test 93 Prediction: 3 True Class: 3
Test 94 Prediction: 1 True Class: 1
Test 95 Prediction: 4 True Class: 4
Test 96 Prediction: 1 True Class: 1
Test 97 Prediction: 7 True Class: 7
Test 98 Prediction: 6 True Class: 6
Test 99 Prediction: 9 True Class: 9
Test 100 Prediction: 6 True Class: 6
Test 101 Prediction: 0 True Class: 0
Test 102 Prediction: 5 True Class: 5
Test 103 Prediction: 4 True Class: 4
Test 104 Prediction: 9 True Class: 9
Test 105 Prediction: 9 True Class: 9
Test 106 Prediction: 2 True Class: 2
Test 107 Prediction: 1 True Class: 1
Test 108 Prediction: 9 True Class: 9
Test 109 Prediction: 4 True Class: 4
Test 110 Prediction: 8 True Class: 8
Test 111 Prediction: 7 True Class: 7
Test 112 Prediction: 3 True Class: 3
Test 113 Prediction: 9 True Class: 9
Test 114 Prediction: 7 True Class: 7
Test 115 Prediction: 9 True Class: 4
Test 116 Prediction: 9 True Class: 4
Test 117 Prediction: 4 True Class: 4
Test 118 Prediction: 9 True Class: 9
Test 119 Prediction: 7 True Class: 2
Test 120 Prediction: 5 True Class: 5
Test 121 Prediction: 4 True Class: 4
Test 122 Prediction: 7 True Class: 7
Test 123 Prediction: 6 True Class: 6
Test 124 Prediction: 7 True Class: 7
Test 125 Prediction: 9 True Class: 9
Test 126 Prediction: 0 True Class: 0
Test 127 Prediction: 5 True Class: 5
Test 128 Prediction: 8 True Class: 8
Test 129 Prediction: 5 True Class: 5
Test 130 Prediction: 6 True Class: 6
Test 131 Prediction: 6 True Class: 6
Test 132 Prediction: 5 True Class: 5
Test 133 Prediction: 7 True Class: 7
Test 134 Prediction: 8 True Class: 8
Test 135 Prediction: 1 True Class: 1
Test 136 Prediction: 0 True Class: 0
Test 137 Prediction: 1 True Class: 1
Test 138 Prediction: 6 True Class: 6
Test 139 Prediction: 4 True Class: 4
Test 140 Prediction: 6 True Class: 6
Test 141 Prediction: 7 True Class: 7
Test 142 Prediction: 2 True Class: 3
Test 143 Prediction: 1 True Class: 1
Test 144 Prediction: 7 True Class: 7
Test 145 Prediction: 1 True Class: 1
Test 146 Prediction: 8 True Class: 8
Test 147 Prediction: 2 True Class: 2
Test 148 Prediction: 0 True Class: 0
Test 149 Prediction: 1 True Class: 2
Test 150 Prediction: 9 True Class: 9
Test 151 Prediction: 9 True Class: 9
Test 152 Prediction: 5 True Class: 5
Test 153 Prediction: 5 True Class: 5
Test 154 Prediction: 1 True Class: 1
Test 155 Prediction: 5 True Class: 5
Test 156 Prediction: 6 True Class: 6
Test 157 Prediction: 0 True Class: 0
Test 158 Prediction: 3 True Class: 3
Test 159 Prediction: 4 True Class: 4
Test 160 Prediction: 4 True Class: 4
Test 161 Prediction: 6 True Class: 6
Test 162 Prediction: 5 True Class: 5
Test 163 Prediction: 4 True Class: 4
Test 164 Prediction: 6 True Class: 6
Test 165 Prediction: 5 True Class: 5
Test 166 Prediction: 4 True Class: 4
Test 167 Prediction: 5 True Class: 5
Test 168 Prediction: 1 True Class: 1
Test 169 Prediction: 4 True Class: 4
Test 170 Prediction: 9 True Class: 4
Test 171 Prediction: 7 True Class: 7
Test 172 Prediction: 2 True Class: 2
Test 173 Prediction: 3 True Class: 3
Test 174 Prediction: 2 True Class: 2
Test 175 Prediction: 1 True Class: 7
Test 176 Prediction: 1 True Class: 1
Test 177 Prediction: 8 True Class: 8
Test 178 Prediction: 1 True Class: 1
Test 179 Prediction: 8 True Class: 8
Test 180 Prediction: 1 True Class: 1
Test 181 Prediction: 8 True Class: 8
Test 182 Prediction: 5 True Class: 5
Test 183 Prediction: 0 True Class: 0
Test 184 Prediction: 2 True Class: 8
Test 185 Prediction: 9 True Class: 9
Test 186 Prediction: 2 True Class: 2
Test 187 Prediction: 5 True Class: 5
Test 188 Prediction: 0 True Class: 0
Test 189 Prediction: 1 True Class: 1
Test 190 Prediction: 1 True Class: 1
Test 191 Prediction: 1 True Class: 1
Test 192 Prediction: 0 True Class: 0
Test 193 Prediction: 4 True Class: 9
Test 194 Prediction: 0 True Class: 0
Test 195 Prediction: 1 True Class: 3
Test 196 Prediction: 1 True Class: 1
Test 197 Prediction: 6 True Class: 6
Test 198 Prediction: 4 True Class: 4
Test 199 Prediction: 2 True Class: 2
Done!
Accuracy: 0.92