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code/13-丢弃法.ipynb

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+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "id": "d5195177",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import torch\n",
+    "from torch import nn\n",
+    "from d2l import torch as d2l\n",
+    "\n",
+    "def dropout_layer (X,dropout):   #X为dropout层的输入，dropout为设置的丢弃概率\n",
+    "    assert 0<=dropout<=1        #丢弃概率介于0，1之间\n",
+    "    if dropout == 1:\n",
+    "       return torch.zeros_like(X) #若丢弃概率为1，则X的全部项均被置0\n",
+    "    if dropout == 0:\n",
+    "       return X                   #若丢弃概率为0，不对X作丢弃操作，直接返回X\n",
+    "    mask=(torch.Tensor(X.shape).uniform_(0,1)>dropout).float() #用uniform函数生成0-1间的随机实数，利用”>\"，将大于dropout的记为1，小于dropout的记为0，实现丢弃操作\n",
+    "    return mask*X/(1-dropout) #将mask与X相乘实现丢弃操作，并除以(1-dropout)，这里不使用选中X中元素置0的原因是相乘操作相比选中操作更快"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "id": "8ff5ba10",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "tensor([[ 0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.],\n",
+      "        [ 8.,  9., 10., 11., 12., 13., 14., 15.]])\n",
+      "tensor([[ 0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.],\n",
+      "        [ 8.,  9., 10., 11., 12., 13., 14., 15.]])\n",
+      "tensor([[ 0.,  0.,  4.,  0.,  0., 10.,  0., 14.],\n",
+      "        [16., 18., 20.,  0.,  0., 26.,  0., 30.]])\n",
+      "tensor([[0., 0., 0., 0., 0., 0., 0., 0.],\n",
+      "        [0., 0., 0., 0., 0., 0., 0., 0.]])\n"
+     ]
+    }
+   ],
+   "source": [
+    "#丢弃法测试\n",
+    "X=torch.arange(16,dtype=torch.float32).reshape((2,8))\n",
+    "print(X)\n",
+    "print(dropout_layer (X,0.))  #丢弃率设置为0\n",
+    "print(dropout_layer (X,0.5)) #丢弃率设置为0.5\n",
+    "print(dropout_layer (X,1))   #丢弃率设置为1"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python [conda env:py36torch040]",
+   "language": "python",
+   "name": "conda-env-py36torch040-py"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.13"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}