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"""Abstract Model class for PyTorch neural networks."""
from abc import ABC, abstractmethod
from glob import glob
from pathlib import Path
import re
import shutil
from typing import Callable, Dict, Optional, Tuple, Type
from loguru import logger
import torch
from torch import nn
from torchsummary import summary
WEIGHT_DIRNAME = Path(__file__).parents[1].resolve() / "weights"
class Model(ABC):
"""Abstract Model class with composition of different parts defining a PyTorch neural network."""
def __init__(
self,
network_fn: Type[nn.Module],
network_args: Dict,
data_loader: Optional[Callable] = None,
data_loader_args: Optional[Dict] = None,
metrics: Optional[Dict] = None,
criterion: Optional[Callable] = None,
criterion_args: Optional[Dict] = None,
optimizer: Optional[Callable] = None,
optimizer_args: Optional[Dict] = None,
lr_scheduler: Optional[Callable] = None,
lr_scheduler_args: Optional[Dict] = None,
device: Optional[str] = None,
) -> None:
"""Base class, to be inherited by model for specific type of data.
Args:
network_fn (Type[nn.Module]): The PyTorch network.
network_args (Dict): Arguments for the network.
data_loader (Optional[Callable]): A function that fetches train and val DataLoader.
data_loader_args (Optional[Dict]): Arguments for the DataLoader.
metrics (Optional[Dict]): Metrics to evaluate the performance with. Defaults to None.
criterion (Optional[Callable]): The criterion to evaulate the preformance of the network.
Defaults to None.
criterion_args (Optional[Dict]): Dict of arguments for criterion. Defaults to None.
optimizer (Optional[Callable]): The optimizer for updating the weights. Defaults to None.
optimizer_args (Optional[Dict]): Dict of arguments for optimizer. Defaults to None.
lr_scheduler (Optional[Callable]): A PyTorch learning rate scheduler. Defaults to None.
lr_scheduler_args (Optional[Dict]): Dict of arguments for learning rate scheduler. Defaults to
None.
device (Optional[str]): Name of the device to train on. Defaults to None.
"""
# Fetch data loaders.
if data_loader_args is not None:
self._data_loaders = data_loader(**data_loader_args)
dataset_name = self._data_loaders.__name__
else:
dataset_name = "*"
self._data_loaders = None
self._name = f"{self.__class__.__name__}_{dataset_name}_{network_fn.__name__}"
# Extract the input shape for the torchsummary.
if isinstance(network_args["input_size"], int):
self._input_shape = (1,) + tuple([network_args["input_size"]])
else:
self._input_shape = (1,) + tuple(network_args["input_size"])
if metrics is not None:
self._metrics = metrics
# Set the device.
if device is None:
self._device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
else:
self._device = device
# Load network.
self.network_args = network_args
self._network = network_fn(**self.network_args)
# To device.
self._network.to(self._device)
# Set criterion.
self._criterion = None
if criterion is not None:
self._criterion = criterion(**criterion_args)
# Set optimizer.
self._optimizer = None
if optimizer is not None:
self._optimizer = optimizer(self._network.parameters(), **optimizer_args)
# Set learning rate scheduler.
self._lr_scheduler = None
if lr_scheduler is not None:
# OneCycleLR needs the number of steps in an epoch as an input argument.
if "OneCycleLR" in str(lr_scheduler):
lr_scheduler_args["steps_per_epoch"] = len(self._data_loaders("train"))
self._lr_scheduler = lr_scheduler(self._optimizer, **lr_scheduler_args)
# Class mapping.
self._mapping = None
@property
def __name__(self) -> str:
"""Returns the name of the model."""
return self._name
@property
def input_shape(self) -> Tuple[int, ...]:
"""The input shape."""
return self._input_shape
@property
def mapping(self) -> Dict:
"""Returns the class mapping."""
return self._mapping
def eval(self) -> None:
"""Sets the network to evaluation mode."""
self._network.eval()
def train(self) -> None:
"""Sets the network to train mode."""
self._network.train()
@property
def device(self) -> str:
"""Device where the weights are stored, i.e. cpu or cuda."""
return self._device
@property
def metrics(self) -> Optional[Dict]:
"""Metrics."""
return self._metrics
@property
def criterion(self) -> Optional[Callable]:
"""Criterion."""
return self._criterion
@property
def optimizer(self) -> Optional[Callable]:
"""Optimizer."""
return self._optimizer
@property
def lr_scheduler(self) -> Optional[Callable]:
"""Learning rate scheduler."""
return self._lr_scheduler
@property
def data_loaders(self) -> Optional[Dict]:
"""Dataloaders."""
return self._data_loaders
@property
def network(self) -> nn.Module:
"""Neural network."""
return self._network
@property
def weights_filename(self) -> str:
"""Filepath to the network weights."""
WEIGHT_DIRNAME.mkdir(parents=True, exist_ok=True)
return str(WEIGHT_DIRNAME / f"{self._name}_weights.pt")
def summary(self) -> None:
"""Prints a summary of the network architecture."""
device = re.sub("[^A-Za-z]+", "", self.device)
summary(self._network, self._input_shape, device=device)
def _get_state_dict(self) -> Dict:
"""Get the state dict of the model."""
state = {"model_state": self._network.state_dict()}
if self._optimizer is not None:
state["optimizer_state"] = self._optimizer.state_dict()
return state
def load_checkpoint(self, path: Path) -> int:
"""Load a previously saved checkpoint.
Args:
path (Path): Path to the experiment with the checkpoint.
Returns:
epoch (int): The last epoch when the checkpoint was created.
"""
logger.debug("Loading checkpoint...")
if not path.exists():
logger.debug("File does not exist {str(path)}")
checkpoint = torch.load(str(path))
self._network.load_state_dict(checkpoint["model_state"])
if self._optimizer is not None:
self._optimizer.load_state_dict(checkpoint["optimizer_state"])
epoch = checkpoint["epoch"]
return epoch
def save_checkpoint(
self, path: Path, is_best: bool, epoch: int, val_metric: str
) -> None:
"""Saves a checkpoint of the model.
Args:
path (Path): Path to the experiment folder.
is_best (bool): If it is the currently best model.
epoch (int): The epoch of the checkpoint.
val_metric (str): Validation metric.
"""
state = self._get_state_dict()
state["is_best"] = is_best
state["epoch"] = epoch
state["network_args"] = self.network_args
path.mkdir(parents=True, exist_ok=True)
logger.debug("Saving checkpoint...")
filepath = str(path / "last.pt")
torch.save(state, filepath)
if is_best:
logger.debug(
f"Found a new best {val_metric}. Saving best checkpoint and weights."
)
shutil.copyfile(filepath, str(path / "best.pt"))
def load_weights(self) -> None:
"""Load the network weights."""
logger.debug("Loading network weights.")
filename = glob(self.weights_filename)[0]
weights = torch.load(filename, map_location=torch.device(self._device))[
"model_state"
]
self._network.load_state_dict(weights)
def save_weights(self, path: Path) -> None:
"""Save the network weights."""
logger.debug("Saving the best network weights.")
shutil.copyfile(str(path / "best.pt"), self.weights_filename)
@abstractmethod
def load_mapping(self) -> None:
"""Loads class mapping from network output to character."""
...
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