pytorch_ipynb/basic-ml/softmax-regression.ipynb

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   "source": [
    "Deep Learning Models -- A collection of various deep learning architectures, models, and tips for TensorFlow and PyTorch in Jupyter Notebooks.\n",
    "- Author: Sebastian Raschka\n",
    "- GitHub Repository: https://github.com/rasbt/deeplearning-models"
   ]
  },
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   "execution_count": 1,
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     "text": [
      "Sebastian Raschka \n",
      "\n",
      "CPython 3.6.8\n",
      "IPython 7.2.0\n",
      "\n",
      "torch 1.0.0\n"
     ]
    }
   ],
   "source": [
    "%load_ext watermark\n",
    "%watermark -a 'Sebastian Raschka' -v -p torch"
   ]
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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- Runs on CPU or GPU (if available)"
   ]
  },
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   "source": [
    "# Model Zoo -- Softmax Regression"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Implementation of softmax regression (multinomial logistic regression)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Imports"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "from torchvision import datasets\n",
    "from torchvision import transforms\n",
    "from torch.utils.data import DataLoader\n",
    "import torch.nn.functional as F\n",
    "import torch"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Settings and Dataset"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Image batch dimensions: torch.Size([256, 1, 28, 28])\n",
      "Image label dimensions: torch.Size([256])\n"
     ]
    }
   ],
   "source": [
    "##########################\n",
    "### SETTINGS\n",
    "##########################\n",
    "\n",
    "# Device\n",
    "device = torch.device(\"cuda:0\" if torch.cuda.is_available() else \"cpu\")\n",
    "\n",
    "# Hyperparameters\n",
    "random_seed = 123\n",
    "learning_rate = 0.1\n",
    "num_epochs = 10\n",
    "batch_size = 256\n",
    "\n",
    "# Architecture\n",
    "num_features = 784\n",
    "num_classes = 10\n",
    "\n",
    "\n",
    "##########################\n",
    "### MNIST DATASET\n",
    "##########################\n",
    "\n",
    "train_dataset = datasets.MNIST(root='data', \n",
    "                               train=True, \n",
    "                               transform=transforms.ToTensor(),  \n",
    "                               download=True)\n",
    "\n",
    "test_dataset = datasets.MNIST(root='data', \n",
    "                              train=False, \n",
    "                              transform=transforms.ToTensor())\n",
    "\n",
    "\n",
    "train_loader = DataLoader(dataset=train_dataset, \n",
    "                          batch_size=batch_size, \n",
    "                          shuffle=True)\n",
    "\n",
    "test_loader = DataLoader(dataset=test_dataset, \n",
    "                         batch_size=batch_size, \n",
    "                         shuffle=False)\n",
    "\n",
    "\n",
    "# Checking the dataset\n",
    "for images, labels in train_loader:  \n",
    "    print('Image batch dimensions:', images.shape)\n",
    "    print('Image label dimensions:', labels.shape)\n",
    "    break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "##########################\n",
    "### MODEL\n",
    "##########################\n",
    "\n",
    "class SoftmaxRegression(torch.nn.Module):\n",
    "\n",
    "    def __init__(self, num_features, num_classes):\n",
    "        super(SoftmaxRegression, self).__init__()\n",
    "        self.linear = torch.nn.Linear(num_features, num_classes)\n",
    "        \n",
    "        self.linear.weight.detach().zero_()\n",
    "        self.linear.bias.detach().zero_()\n",
    "        \n",
    "    def forward(self, x):\n",
    "        logits = self.linear(x)\n",
    "        probas = F.softmax(logits, dim=1)\n",
    "        return logits, probas\n",
    "\n",
    "model = SoftmaxRegression(num_features=num_features,\n",
    "                          num_classes=num_classes)\n",
    "\n",
    "model.to(device)\n",
    "\n",
    "##########################\n",
    "### COST AND OPTIMIZER\n",
    "##########################\n",
    "\n",
    "optimizer = torch.optim.SGD(model.parameters(), lr=learning_rate)  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Epoch: 001/010 | Batch 000/234 | Cost: 2.3026\n",
      "Epoch: 001/010 | Batch 050/234 | Cost: 0.7941\n",
      "Epoch: 001/010 | Batch 100/234 | Cost: 0.5651\n",
      "Epoch: 001/010 | Batch 150/234 | Cost: 0.4603\n",
      "Epoch: 001/010 | Batch 200/234 | Cost: 0.4822\n",
      "Epoch: 001/010 training accuracy: 88.04%\n",
      "Epoch: 002/010 | Batch 000/234 | Cost: 0.4105\n",
      "Epoch: 002/010 | Batch 050/234 | Cost: 0.4415\n",
      "Epoch: 002/010 | Batch 100/234 | Cost: 0.4367\n",
      "Epoch: 002/010 | Batch 150/234 | Cost: 0.4289\n",
      "Epoch: 002/010 | Batch 200/234 | Cost: 0.3926\n",
      "Epoch: 002/010 training accuracy: 89.37%\n",
      "Epoch: 003/010 | Batch 000/234 | Cost: 0.4112\n",
      "Epoch: 003/010 | Batch 050/234 | Cost: 0.3579\n",
      "Epoch: 003/010 | Batch 100/234 | Cost: 0.3013\n",
      "Epoch: 003/010 | Batch 150/234 | Cost: 0.3258\n",
      "Epoch: 003/010 | Batch 200/234 | Cost: 0.4254\n",
      "Epoch: 003/010 training accuracy: 89.98%\n",
      "Epoch: 004/010 | Batch 000/234 | Cost: 0.3988\n",
      "Epoch: 004/010 | Batch 050/234 | Cost: 0.3690\n",
      "Epoch: 004/010 | Batch 100/234 | Cost: 0.3459\n",
      "Epoch: 004/010 | Batch 150/234 | Cost: 0.4030\n",
      "Epoch: 004/010 | Batch 200/234 | Cost: 0.3240\n",
      "Epoch: 004/010 training accuracy: 90.35%\n",
      "Epoch: 005/010 | Batch 000/234 | Cost: 0.3265\n",
      "Epoch: 005/010 | Batch 050/234 | Cost: 0.3673\n",
      "Epoch: 005/010 | Batch 100/234 | Cost: 0.3085\n",
      "Epoch: 005/010 | Batch 150/234 | Cost: 0.3183\n",
      "Epoch: 005/010 | Batch 200/234 | Cost: 0.3316\n",
      "Epoch: 005/010 training accuracy: 90.64%\n",
      "Epoch: 006/010 | Batch 000/234 | Cost: 0.4518\n",
      "Epoch: 006/010 | Batch 050/234 | Cost: 0.3863\n",
      "Epoch: 006/010 | Batch 100/234 | Cost: 0.3620\n",
      "Epoch: 006/010 | Batch 150/234 | Cost: 0.3733\n",
      "Epoch: 006/010 | Batch 200/234 | Cost: 0.3289\n",
      "Epoch: 006/010 training accuracy: 90.86%\n",
      "Epoch: 007/010 | Batch 000/234 | Cost: 0.3450\n",
      "Epoch: 007/010 | Batch 050/234 | Cost: 0.2289\n",
      "Epoch: 007/010 | Batch 100/234 | Cost: 0.3073\n",
      "Epoch: 007/010 | Batch 150/234 | Cost: 0.2750\n",
      "Epoch: 007/010 | Batch 200/234 | Cost: 0.3456\n",
      "Epoch: 007/010 training accuracy: 91.00%\n",
      "Epoch: 008/010 | Batch 000/234 | Cost: 0.4900\n",
      "Epoch: 008/010 | Batch 050/234 | Cost: 0.3479\n",
      "Epoch: 008/010 | Batch 100/234 | Cost: 0.2343\n",
      "Epoch: 008/010 | Batch 150/234 | Cost: 0.3059\n",
      "Epoch: 008/010 | Batch 200/234 | Cost: 0.3684\n",
      "Epoch: 008/010 training accuracy: 91.22%\n",
      "Epoch: 009/010 | Batch 000/234 | Cost: 0.3762\n",
      "Epoch: 009/010 | Batch 050/234 | Cost: 0.2976\n",
      "Epoch: 009/010 | Batch 100/234 | Cost: 0.2690\n",
      "Epoch: 009/010 | Batch 150/234 | Cost: 0.2610\n",
      "Epoch: 009/010 | Batch 200/234 | Cost: 0.3140\n",
      "Epoch: 009/010 training accuracy: 91.34%\n",
      "Epoch: 010/010 | Batch 000/234 | Cost: 0.2790\n",
      "Epoch: 010/010 | Batch 050/234 | Cost: 0.3070\n",
      "Epoch: 010/010 | Batch 100/234 | Cost: 0.3300\n",
      "Epoch: 010/010 | Batch 150/234 | Cost: 0.2520\n",
      "Epoch: 010/010 | Batch 200/234 | Cost: 0.3301\n",
      "Epoch: 010/010 training accuracy: 91.40%\n"
     ]
    }
   ],
   "source": [
    "# Manual seed for deterministic data loader\n",
    "torch.manual_seed(random_seed)\n",
    "\n",
    "\n",
    "def compute_accuracy(model, data_loader):\n",
    "    correct_pred, num_examples = 0, 0\n",
    "    \n",
    "    for features, targets in data_loader:\n",
    "        features = features.view(-1, 28*28).to(device)\n",
    "        targets = targets.to(device)\n",
    "        logits, probas = model(features)\n",
    "        _, predicted_labels = torch.max(probas, 1)\n",
    "        num_examples += targets.size(0)\n",
    "        correct_pred += (predicted_labels == targets).sum()\n",
    "        \n",
    "    return correct_pred.float() / num_examples * 100\n",
    "    \n",
    "\n",
    "for epoch in range(num_epochs):\n",
    "    for batch_idx, (features, targets) in enumerate(train_loader):\n",
    "        \n",
    "        features = features.view(-1, 28*28).to(device)\n",
    "        targets = targets.to(device)\n",
    "            \n",
    "        ### FORWARD AND BACK PROP\n",
    "        logits, probas = model(features)\n",
    "        \n",
    "        # note that the PyTorch implementation of\n",
    "        # CrossEntropyLoss works with logits, not\n",
    "        # probabilities\n",
    "        cost = F.cross_entropy(logits, targets)\n",
    "        optimizer.zero_grad()\n",
    "        cost.backward()\n",
    "        \n",
    "        ### UPDATE MODEL PARAMETERS\n",
    "        optimizer.step()\n",
    "        \n",
    "        ### LOGGING\n",
    "        if not batch_idx % 50:\n",
    "            print ('Epoch: %03d/%03d | Batch %03d/%03d | Cost: %.4f' \n",
    "                   %(epoch+1, num_epochs, batch_idx, \n",
    "                     len(train_dataset)//batch_size, cost))\n",
    "            \n",
    "    with torch.set_grad_enabled(False):\n",
    "        print('Epoch: %03d/%03d training accuracy: %.2f%%' % (\n",
    "              epoch+1, num_epochs, \n",
    "              compute_accuracy(model, train_loader)))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Test accuracy: 91.77%\n"
     ]
    }
   ],
   "source": [
    "print('Test accuracy: %.2f%%' % (compute_accuracy(model, test_loader)))"
   ]
  },
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   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "torch       1.0.0\n",
      "\n"
     ]
    }
   ],
   "source": [
    "%watermark -iv"
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