Laboratoria 4. Sieci neuronowe
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Paweł Skórzewski
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lab/4_Sieci_neuronowe_PyTorch.ipynb
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lab/4_Sieci_neuronowe_PyTorch.ipynb
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"cells": [
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"cell_type": "markdown",
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"slide_type": "-"
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"source": [
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"### AITech — Uczenie maszynowe — laboratoria\n",
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"# 4. Sieci neuronowe (PyTorch)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Przykład implementacji sieci neuronowej do rozpoznawania cyfr ze zbioru MNIST, według https://github.com/pytorch/examples/tree/master/mnist"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"import torch\n",
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"import torch.nn as nn\n",
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"import torch.nn.functional as F\n",
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"import torch.optim as optim\n",
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"from torchvision import datasets, transforms\n",
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"from torch.optim.lr_scheduler import StepLR\n",
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"\n",
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"\n",
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"class Net(nn.Module):\n",
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" \"\"\"W PyTorchu tworzenie sieci neuronowej\n",
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" polega na zdefiniowaniu klasy, która dziedziczy z nn.Module.\n",
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" \"\"\"\n",
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" \n",
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" def __init__(self):\n",
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" super().__init__()\n",
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" \n",
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" # Warstwy splotowe\n",
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" self.conv1 = nn.Conv2d(1, 32, 3, 1)\n",
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" self.conv2 = nn.Conv2d(32, 64, 3, 1)\n",
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" \n",
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" # Warstwy dropout\n",
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" self.dropout1 = nn.Dropout(0.25)\n",
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" self.dropout2 = nn.Dropout(0.5)\n",
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" \n",
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" # Warstwy liniowe\n",
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" self.fc1 = nn.Linear(9216, 128)\n",
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" self.fc2 = nn.Linear(128, 10)\n",
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"\n",
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" def forward(self, x):\n",
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" \"\"\"Definiujemy przechodzenie \"do przodu\" jako kolejne przekształcenia wejścia x\"\"\"\n",
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" x = self.conv1(x)\n",
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" x = F.relu(x)\n",
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" x = self.conv2(x)\n",
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" x = F.relu(x)\n",
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" x = F.max_pool2d(x, 2)\n",
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" x = self.dropout1(x)\n",
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" x = torch.flatten(x, 1)\n",
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" x = self.fc1(x)\n",
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" x = F.relu(x)\n",
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" x = self.dropout2(x)\n",
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" x = self.fc2(x)\n",
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" output = F.log_softmax(x, dim=1)\n",
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" return output\n",
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"\n",
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"\n",
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"def train(model, device, train_loader, optimizer, epoch, log_interval, dry_run):\n",
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" \"\"\"Uczenie modelu\"\"\"\n",
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" model.train()\n",
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" for batch_idx, (data, target) in enumerate(train_loader):\n",
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" data, target = data.to(device), target.to(device) # wrzucenie danych na kartę graficzną (jeśli dotyczy)\n",
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" optimizer.zero_grad() # wyzerowanie gradientu\n",
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" output = model(data) # przejście \"do przodu\"\n",
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" loss = F.nll_loss(output, target) # obliczenie funkcji kosztu\n",
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" loss.backward() # propagacja wsteczna\n",
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" optimizer.step() # krok optymalizatora\n",
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" if batch_idx % log_interval == 0:\n",
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" print('Train Epoch: {} [{}/{} ({:.0f}%)]\\tLoss: {:.6f}'.format(\n",
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" epoch, batch_idx * len(data), len(train_loader.dataset),\n",
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" 100. * batch_idx / len(train_loader), loss.item()))\n",
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" if dry_run:\n",
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" break\n",
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"\n",
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"\n",
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"def test(model, device, test_loader):\n",
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" \"\"\"Testowanie modelu\"\"\"\n",
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" model.eval()\n",
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" test_loss = 0\n",
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" correct = 0\n",
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" with torch.no_grad():\n",
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" for data, target in test_loader:\n",
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" data, target = data.to(device), target.to(device) # wrzucenie danych na kartę graficzną (jeśli dotyczy)\n",
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" output = model(data) # przejście \"do przodu\"\n",
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" test_loss += F.nll_loss(output, target, reduction='sum').item() # suma kosztów z każdego batcha\n",
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" pred = output.argmax(dim=1, keepdim=True) # predykcja na podstawie maks. logarytmu prawdopodobieństwa\n",
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" correct += pred.eq(target.view_as(pred)).sum().item()\n",
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"\n",
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" test_loss /= len(test_loader.dataset) # obliczenie kosztu na zbiorze testowym\n",
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"\n",
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" print('\\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\\n'.format(\n",
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" test_loss, correct, len(test_loader.dataset),\n",
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" 100. * correct / len(test_loader.dataset)))\n",
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"\n",
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"\n",
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"def run(\n",
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" batch_size=64,\n",
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" test_batch_size=1000,\n",
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" epochs=14,\n",
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" lr=1.0,\n",
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" gamma=0.7,\n",
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" no_cuda=False,\n",
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" dry_run=False,\n",
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" seed=1,\n",
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" log_interval=10,\n",
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" save_model=False,\n",
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" ):\n",
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" \"\"\"Main training function.\n",
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" \n",
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" Arguments:\n",
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" batch_size - wielkość batcha podczas uczenia (default: 64),\n",
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" test_batch_size - wielkość batcha podczas testowania (default: 1000)\n",
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" epochs - liczba epok uczenia (default: 14)\n",
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" lr - współczynnik uczenia (learning rate) (default: 1.0)\n",
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" gamma - współczynnik gamma (dla optymalizatora) (default: 0.7)\n",
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" no_cuda - wyłącza uczenie na karcie graficznej (default: False)\n",
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" dry_run - szybko (\"na sucho\") sprawdza pojedyncze przejście (default: False)\n",
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" seed - ziarno generatora liczb pseudolosowych (default: 1)\n",
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" log_interval - interwał logowania stanu uczenia (default: 10)\n",
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" save_model - zapisuje bieżący model (default: False)\n",
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" \"\"\"\n",
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" use_cuda = no_cuda and torch.cuda.is_available()\n",
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"\n",
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" torch.manual_seed(seed)\n",
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"\n",
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" device = torch.device(\"cuda\" if use_cuda else \"cpu\")\n",
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"\n",
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" train_kwargs = {'batch_size': batch_size}\n",
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" test_kwargs = {'batch_size': test_batch_size}\n",
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" if use_cuda:\n",
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" cuda_kwargs = {'num_workers': 1,\n",
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" 'pin_memory': True,\n",
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" 'shuffle': True}\n",
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" train_kwargs.update(cuda_kwargs)\n",
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" test_kwargs.update(cuda_kwargs)\n",
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"\n",
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" transform=transforms.Compose([\n",
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" transforms.ToTensor(),\n",
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" transforms.Normalize((0.1307,), (0.3081,))\n",
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" ])\n",
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" dataset1 = datasets.MNIST('../data', train=True, download=True,\n",
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" transform=transform)\n",
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" dataset2 = datasets.MNIST('../data', train=False,\n",
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" transform=transform)\n",
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" train_loader = torch.utils.data.DataLoader(dataset1,**train_kwargs)\n",
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" test_loader = torch.utils.data.DataLoader(dataset2, **test_kwargs)\n",
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"\n",
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" model = Net().to(device)\n",
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" optimizer = optim.Adadelta(model.parameters(), lr=lr)\n",
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"\n",
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" scheduler = StepLR(optimizer, step_size=1, gamma=gamma)\n",
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" for epoch in range(1, epochs + 1):\n",
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" train(model, device, train_loader, optimizer, epoch, log_interval, dry_run)\n",
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" test(model, device, test_loader)\n",
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" scheduler.step()\n",
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"\n",
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" if save_model:\n",
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" torch.save(model.state_dict(), \"mnist_cnn.pt\")"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"**Uwaga**: uruchomienie tego przykładu długo trwa. Żeby trwało krócej, można zmniejszyć liczbę epok."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"run(epochs=5)"
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]
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}
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],
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"metadata": {
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"celltoolbar": "Slideshow",
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"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.8.3"
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"livereveal": {
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"start_slideshow_at": "selected",
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"nbformat": 4,
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"nbformat_minor": 4
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