Source code for ax.utils.tutorials.cnn_utils

#!/usr/bin/env python3
# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

from itertools import accumulate
from typing import Dict, List, Optional, Tuple

import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.optim as optim
import torchvision
import torchvision.transforms as transforms
from torch.utils.data import DataLoader, Dataset, Subset


[docs]class CNN(nn.Module): """ Convolutional Neural Network. """ def __init__(self): super().__init__() self.conv1 = nn.Conv2d(1, 20, kernel_size=5, stride=1) self.fc1 = nn.Linear(8 * 8 * 20, 64) self.fc2 = nn.Linear(64, 10)
[docs] def forward(self, x): x = F.relu(self.conv1(x)) x = F.max_pool2d(x, 3, 3) x = x.view(-1, 8 * 8 * 20) x = F.relu(self.fc1(x)) x = self.fc2(x) return F.log_softmax(x, dim=-1)
[docs]def load_mnist( downsample_pct: float = 0.5, train_pct: float = 0.8, data_path: str = "./data", batch_size: int = 128, num_workers: int = 0, deterministic_partitions: bool = False, downsample_pct_test: Optional[float] = None, ) -> Tuple[DataLoader, DataLoader, DataLoader]: """ Load MNIST dataset (download if necessary) and split data into training, validation, and test sets. Args: downsample_pct: the proportion of the dataset to use for training, validation, and test train_pct: the proportion of the downsampled data to use for training data_path: Root directory of dataset where `MNIST/processed/training.pt` and `MNIST/processed/test.pt` exist. batch_size: how many samples per batch to load num_workers: number of workers (subprocesses) for loading data deterministic_partitions: whether to partition data in a deterministic fashion downsample_pct_test: the proportion of the dataset to use for test, default to be equal to downsample_pct Returns: DataLoader: training data DataLoader: validation data DataLoader: test data """ # Specify transforms transform = transforms.Compose( [transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,))] ) # Load training set train_valid_set = torchvision.datasets.MNIST( root=data_path, train=True, download=True, transform=transform ) # Load test set test_set = torchvision.datasets.MNIST( root=data_path, train=False, download=True, transform=transform ) return get_partition_data_loaders( train_valid_set=train_valid_set, test_set=test_set, downsample_pct=downsample_pct, train_pct=train_pct, batch_size=batch_size, num_workers=num_workers, deterministic_partitions=deterministic_partitions, downsample_pct_test=downsample_pct_test, )
[docs]def get_partition_data_loaders( train_valid_set: Dataset, test_set: Dataset, downsample_pct: float = 0.5, train_pct: float = 0.8, batch_size: int = 128, num_workers: int = 0, deterministic_partitions: bool = False, downsample_pct_test: Optional[float] = None, ) -> Tuple[DataLoader, DataLoader, DataLoader]: """ Helper function for partitioning training data into training and validation sets, downsampling data, and initializing DataLoaders for each partition. Args: train_valid_set: torch.dataset downsample_pct: the proportion of the dataset to use for training, and validation train_pct: the proportion of the downsampled data to use for training batch_size: how many samples per batch to load num_workers: number of workers (subprocesses) for loading data deterministic_partitions: whether to partition data in a deterministic fashion downsample_pct_test: the proportion of the dataset to use for test, default to be equal to downsample_pct Returns: DataLoader: training data DataLoader: validation data DataLoader: test data """ # Partition into training/validation # pyre-ignore [6] downsampled_num_examples = int(downsample_pct * len(train_valid_set)) n_train_examples = int(train_pct * downsampled_num_examples) n_valid_examples = downsampled_num_examples - n_train_examples train_set, valid_set, _ = split_dataset( dataset=train_valid_set, lengths=[ n_train_examples, n_valid_examples, len(train_valid_set) - downsampled_num_examples, # pyre-ignore [6] ], deterministic_partitions=deterministic_partitions, ) if downsample_pct_test is None: downsample_pct_test = downsample_pct # pyre-ignore [6] downsampled_num_test_examples = int(downsample_pct_test * len(test_set)) test_set, _ = split_dataset( test_set, lengths=[ downsampled_num_test_examples, len(test_set) - downsampled_num_test_examples, # pyre-ignore [6] ], deterministic_partitions=deterministic_partitions, ) train_loader = DataLoader( train_set, batch_size=batch_size, shuffle=True, num_workers=num_workers ) valid_loader = DataLoader( valid_set, batch_size=batch_size, shuffle=False, num_workers=num_workers ) test_loader = DataLoader( test_set, batch_size=batch_size, shuffle=False, num_workers=num_workers ) return train_loader, valid_loader, test_loader
[docs]def split_dataset( dataset: Dataset, lengths: List[int], deterministic_partitions: bool = False ) -> List[Dataset]: """ Split a dataset either randomly or deterministically. Args: dataset: the dataset to split lengths: the lengths of each partition deterministic_partitions: deterministic_partitions: whether to partition data in a deterministic fashion Returns: List[Dataset]: split datasets """ if deterministic_partitions: indices = list(range(sum(lengths))) else: indices = torch.randperm(sum(lengths)).tolist() return [ Subset(dataset, indices[offset - length : offset]) for offset, length in zip(accumulate(lengths), lengths) ]
[docs]def train( net: torch.nn.Module, train_loader: DataLoader, parameters: Dict[str, float], dtype: torch.dtype, device: torch.device, ) -> nn.Module: """ Train CNN on provided data set. Args: net: initialized neural network train_loader: DataLoader containing training set parameters: dictionary containing parameters to be passed to the optimizer. - lr: default (0.001) - momentum: default (0.0) - weight_decay: default (0.0) - num_epochs: default (1) dtype: torch dtype device: torch device Returns: nn.Module: trained CNN. """ # Initialize network net.to(dtype=dtype, device=device) net.train() # Define loss and optimizer criterion = nn.NLLLoss(reduction="sum") optimizer = optim.SGD( net.parameters(), lr=parameters.get("lr", 0.001), momentum=parameters.get("momentum", 0.0), weight_decay=parameters.get("weight_decay", 0.0), ) scheduler = optim.lr_scheduler.StepLR( optimizer, step_size=int(parameters.get("step_size", 30)), gamma=parameters.get("gamma", 1.0), # default is no learning rate decay ) num_epochs = parameters.get("num_epochs", 1) # Train Network # pyre-fixme[6]: Expected `int` for 1st param but got `float`. for _ in range(num_epochs): for inputs, labels in train_loader: # move data to proper dtype and device inputs = inputs.to(dtype=dtype, device=device) labels = labels.to(device=device) # zero the parameter gradients optimizer.zero_grad() # forward + backward + optimize outputs = net(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() scheduler.step() return net
[docs]def evaluate( net: nn.Module, data_loader: DataLoader, dtype: torch.dtype, device: torch.device ) -> float: """ Compute classification accuracy on provided dataset. Args: net: trained model data_loader: DataLoader containing the evaluation set dtype: torch dtype device: torch device Returns: float: classification accuracy """ net.eval() correct = 0 total = 0 with torch.no_grad(): for inputs, labels in data_loader: # move data to proper dtype and device inputs = inputs.to(dtype=dtype, device=device) labels = labels.to(device=device) outputs = net(inputs) _, predicted = torch.max(outputs.data, 1) total += labels.size(0) correct += (predicted == labels).sum().item() return correct / total