|
| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "markdown", |
| 5 | + "metadata": {}, |
| 6 | + "source": [ |
| 7 | + "# 动态图和静态图\n", |
| 8 | + "PyTorch 和 TensorFlow、Caffe 等框架最大的区别就是他们拥有不同的计算图表现形式。 TensorFlow 使用静态图,这意味着我们先定义计算图,然后不断使用它,在 PyTorch 中,每次都会重新构建一个新的计算图。\n", |
| 9 | + "\n", |
| 10 | + "对于使用者来说,两种形式的计算图有着非常大的区别,同时静态图和动态图都有他们各自的优点,比如动态图比较方便debug,使用者能够用任何他们喜欢的方式进行debug,同时非常直观,而静态图是通过先定义后运行的方式,之后再次运行的时候就不再需要重新构建计算图,所以速度会比动态图更快。" |
| 11 | + ] |
| 12 | + }, |
| 13 | + { |
| 14 | + "cell_type": "markdown", |
| 15 | + "metadata": {}, |
| 16 | + "source": [ |
| 17 | + "" |
| 18 | + ] |
| 19 | + }, |
| 20 | + { |
| 21 | + "cell_type": "markdown", |
| 22 | + "metadata": {}, |
| 23 | + "source": [ |
| 24 | + "下面我们比较 while 循环语句在 TensorFlow 和 PyTorch 中的定义" |
| 25 | + ] |
| 26 | + }, |
| 27 | + { |
| 28 | + "cell_type": "code", |
| 29 | + "execution_count": 1, |
| 30 | + "metadata": { |
| 31 | + "collapsed": true |
| 32 | + }, |
| 33 | + "outputs": [], |
| 34 | + "source": [ |
| 35 | + "# tensorflow\n", |
| 36 | + "import tensorflow as tf\n", |
| 37 | + "\n", |
| 38 | + "first_counter = tf.constant(0)\n", |
| 39 | + "second_counter = tf.constant(10)" |
| 40 | + ] |
| 41 | + }, |
| 42 | + { |
| 43 | + "cell_type": "code", |
| 44 | + "execution_count": 2, |
| 45 | + "metadata": { |
| 46 | + "collapsed": true |
| 47 | + }, |
| 48 | + "outputs": [], |
| 49 | + "source": [ |
| 50 | + "def cond(first_counter, second_counter, *args):\n", |
| 51 | + " return first_counter < second_counter\n", |
| 52 | + "\n", |
| 53 | + "def body(first_counter, second_counter):\n", |
| 54 | + " first_counter = tf.add(first_counter, 2)\n", |
| 55 | + " second_counter = tf.add(second_counter, 1)\n", |
| 56 | + " return first_counter, second_counter" |
| 57 | + ] |
| 58 | + }, |
| 59 | + { |
| 60 | + "cell_type": "code", |
| 61 | + "execution_count": 3, |
| 62 | + "metadata": { |
| 63 | + "collapsed": false |
| 64 | + }, |
| 65 | + "outputs": [], |
| 66 | + "source": [ |
| 67 | + "c1, c2 = tf.while_loop(cond, body, [first_counter, second_counter])" |
| 68 | + ] |
| 69 | + }, |
| 70 | + { |
| 71 | + "cell_type": "code", |
| 72 | + "execution_count": 4, |
| 73 | + "metadata": { |
| 74 | + "collapsed": true |
| 75 | + }, |
| 76 | + "outputs": [], |
| 77 | + "source": [ |
| 78 | + "with tf.Session() as sess:\n", |
| 79 | + " counter_1_res, counter_2_res = sess.run([c1, c2])" |
| 80 | + ] |
| 81 | + }, |
| 82 | + { |
| 83 | + "cell_type": "code", |
| 84 | + "execution_count": 5, |
| 85 | + "metadata": { |
| 86 | + "collapsed": false |
| 87 | + }, |
| 88 | + "outputs": [ |
| 89 | + { |
| 90 | + "name": "stdout", |
| 91 | + "output_type": "stream", |
| 92 | + "text": [ |
| 93 | + "20\n", |
| 94 | + "20\n" |
| 95 | + ] |
| 96 | + } |
| 97 | + ], |
| 98 | + "source": [ |
| 99 | + "print(counter_1_res)\n", |
| 100 | + "print(counter_2_res)" |
| 101 | + ] |
| 102 | + }, |
| 103 | + { |
| 104 | + "cell_type": "code", |
| 105 | + "execution_count": 6, |
| 106 | + "metadata": { |
| 107 | + "collapsed": true |
| 108 | + }, |
| 109 | + "outputs": [], |
| 110 | + "source": [ |
| 111 | + "# pytorch\n", |
| 112 | + "import torch\n", |
| 113 | + "first_counter = torch.Tensor([0])\n", |
| 114 | + "second_counter = torch.Tensor([10])" |
| 115 | + ] |
| 116 | + }, |
| 117 | + { |
| 118 | + "cell_type": "code", |
| 119 | + "execution_count": 11, |
| 120 | + "metadata": { |
| 121 | + "collapsed": false |
| 122 | + }, |
| 123 | + "outputs": [], |
| 124 | + "source": [ |
| 125 | + "while (first_counter < second_counter)[0]:\n", |
| 126 | + " first_counter += 2\n", |
| 127 | + " second_counter += 1" |
| 128 | + ] |
| 129 | + }, |
| 130 | + { |
| 131 | + "cell_type": "code", |
| 132 | + "execution_count": 12, |
| 133 | + "metadata": { |
| 134 | + "collapsed": false |
| 135 | + }, |
| 136 | + "outputs": [ |
| 137 | + { |
| 138 | + "name": "stdout", |
| 139 | + "output_type": "stream", |
| 140 | + "text": [ |
| 141 | + "\n", |
| 142 | + " 20\n", |
| 143 | + "[torch.FloatTensor of size 1]\n", |
| 144 | + "\n", |
| 145 | + "\n", |
| 146 | + " 20\n", |
| 147 | + "[torch.FloatTensor of size 1]\n", |
| 148 | + "\n" |
| 149 | + ] |
| 150 | + } |
| 151 | + ], |
| 152 | + "source": [ |
| 153 | + "print(first_counter)\n", |
| 154 | + "print(second_counter)" |
| 155 | + ] |
| 156 | + }, |
| 157 | + { |
| 158 | + "cell_type": "markdown", |
| 159 | + "metadata": {}, |
| 160 | + "source": [ |
| 161 | + "上面的例子展示如何使用静态图和动态图构建 while 循环,看起来动态图的方式更加简单且直观,你觉得呢?" |
| 162 | + ] |
| 163 | + } |
| 164 | + ], |
| 165 | + "metadata": { |
| 166 | + "kernelspec": { |
| 167 | + "display_name": "mx", |
| 168 | + "language": "python", |
| 169 | + "name": "mx" |
| 170 | + }, |
| 171 | + "language_info": { |
| 172 | + "codemirror_mode": { |
| 173 | + "name": "ipython", |
| 174 | + "version": 3 |
| 175 | + }, |
| 176 | + "file_extension": ".py", |
| 177 | + "mimetype": "text/x-python", |
| 178 | + "name": "python", |
| 179 | + "nbconvert_exporter": "python", |
| 180 | + "pygments_lexer": "ipython3", |
| 181 | + "version": "3.6.0" |
| 182 | + } |
| 183 | + }, |
| 184 | + "nbformat": 4, |
| 185 | + "nbformat_minor": 2 |
| 186 | +} |
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