lightning/pl_examples/basic_examples/image_classifier.py

127 lines
3.9 KiB
Python

# Copyright The PyTorch Lightning team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from argparse import ArgumentParser
import torch
import pytorch_lightning as pl
from torch.nn import functional as F
from torch.utils.data import DataLoader, random_split
try:
from torchvision.datasets.mnist import MNIST
from torchvision import transforms
except Exception as e:
from tests.base.datasets import MNIST
class Backbone(torch.nn.Module):
def __init__(self, hidden_dim=128):
super().__init__()
self.l1 = torch.nn.Linear(28 * 28, hidden_dim)
self.l2 = torch.nn.Linear(hidden_dim, 10)
def forward(self, x):
x = x.view(x.size(0), -1)
x = torch.relu(self.l1(x))
x = torch.relu(self.l2(x))
return x
class LitClassifier(pl.LightningModule):
def __init__(self, backbone, learning_rate=1e-3):
super().__init__()
self.save_hyperparameters()
self.backbone = backbone
def forward(self, x):
# use forward for inference/predictions
embedding = self.backbone(x)
return embedding
def training_step(self, batch, batch_idx):
x, y = batch
y_hat = self.backbone(x)
loss = F.cross_entropy(y_hat, y)
self.log('train_loss', loss, on_epoch=True)
return loss
def validation_step(self, batch, batch_idx):
x, y = batch
y_hat = self.backbone(x)
loss = F.cross_entropy(y_hat, y)
self.log('valid_loss', loss, on_step=True)
def test_step(self, batch, batch_idx):
x, y = batch
y_hat = self.backbone(x)
loss = F.cross_entropy(y_hat, y)
self.log('test_loss', loss)
def configure_optimizers(self):
# self.hparams available because we called self.save_hyperparameters()
return torch.optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
@staticmethod
def add_model_specific_args(parent_parser):
parser = ArgumentParser(parents=[parent_parser], add_help=False)
parser.add_argument('--learning_rate', type=float, default=0.0001)
return parser
def cli_main():
pl.seed_everything(1234)
# ------------
# args
# ------------
parser = ArgumentParser()
parser.add_argument('--batch_size', default=32, type=int)
parser.add_argument('--hidden_dim', type=int, default=128)
parser = pl.Trainer.add_argparse_args(parser)
parser = LitClassifier.add_model_specific_args(parser)
args = parser.parse_args()
# ------------
# data
# ------------
dataset = MNIST('', train=True, download=True, transform=transforms.ToTensor())
mnist_test = MNIST('', train=False, download=True, transform=transforms.ToTensor())
mnist_train, mnist_val = random_split(dataset, [55000, 5000])
train_loader = DataLoader(mnist_train, batch_size=args.batch_size)
val_loader = DataLoader(mnist_val, batch_size=args.batch_size)
test_loader = DataLoader(mnist_test, batch_size=args.batch_size)
# ------------
# model
# ------------
model = LitClassifier(Backbone(hidden_dim=args.hidden_dim), args.learning_rate)
# ------------
# training
# ------------
trainer = pl.Trainer.from_argparse_args(args)
trainer.fit(model, train_loader, val_loader)
# ------------
# testing
# ------------
result = trainer.test(test_dataloaders=test_loader)
print(result)
if __name__ == '__main__':
cli_main()