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Aladdin Persson
2021-03-24 22:09:25 +01:00
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"""
Example code of a simple RNN, GRU, LSTM on the MNIST dataset.
Programmed by Aladdin Persson <aladdin.persson at hotmail dot com>
* 2020-05-09 Initial coding
"""
# Imports
import torch
import torchvision # torch package for vision related things
import torch.nn.functional as F # Parameterless functions, like (some) activation functions
import torchvision.datasets as datasets # Standard datasets
import torchvision.transforms as transforms # Transformations we can perform on our dataset for augmentation
from torch import optim # For optimizers like SGD, Adam, etc.
from torch import nn # All neural network modules
from torch.utils.data import DataLoader # Gives easier dataset managment by creating mini batches etc.
from tqdm import tqdm # For a nice progress bar!
# Set device
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
# Hyperparameters
input_size = 28
hidden_size = 256
num_layers = 2
num_classes = 10
sequence_length = 28
learning_rate = 0.005
batch_size = 64
num_epochs = 3
# Recurrent neural network (many-to-one)
class RNN(nn.Module):
def __init__(self, input_size, hidden_size, num_layers, num_classes):
super(RNN, self).__init__()
self.hidden_size = hidden_size
self.num_layers = num_layers
self.rnn = nn.RNN(input_size, hidden_size, num_layers, batch_first=True)
self.fc = nn.Linear(hidden_size * sequence_length, num_classes)
def forward(self, x):
# Set initial hidden and cell states
h0 = torch.zeros(self.num_layers, x.size(0), self.hidden_size).to(device)
# Forward propagate LSTM
out, _ = self.rnn(x, h0)
out = out.reshape(out.shape[0], -1)
# Decode the hidden state of the last time step
out = self.fc(out)
return out
# Recurrent neural network with GRU (many-to-one)
class RNN_GRU(nn.Module):
def __init__(self, input_size, hidden_size, num_layers, num_classes):
super(RNN_GRU, self).__init__()
self.hidden_size = hidden_size
self.num_layers = num_layers
self.gru = nn.GRU(input_size, hidden_size, num_layers, batch_first=True)
self.fc = nn.Linear(hidden_size * sequence_length, num_classes)
def forward(self, x):
# Set initial hidden and cell states
h0 = torch.zeros(self.num_layers, x.size(0), self.hidden_size).to(device)
# Forward propagate LSTM
out, _ = self.gru(x, h0)
out = out.reshape(out.shape[0], -1)
# Decode the hidden state of the last time step
out = self.fc(out)
return out
# Recurrent neural network with LSTM (many-to-one)
class RNN_LSTM(nn.Module):
def __init__(self, input_size, hidden_size, num_layers, num_classes):
super(RNN_LSTM, self).__init__()
self.hidden_size = hidden_size
self.num_layers = num_layers
self.lstm = nn.LSTM(input_size, hidden_size, num_layers, batch_first=True)
self.fc = nn.Linear(hidden_size * sequence_length, num_classes)
def forward(self, x):
# Set initial hidden and cell states
h0 = torch.zeros(self.num_layers, x.size(0), self.hidden_size).to(device)
c0 = torch.zeros(self.num_layers, x.size(0), self.hidden_size).to(device)
# Forward propagate LSTM
out, _ = self.lstm(
x, (h0, c0)
) # out: tensor of shape (batch_size, seq_length, hidden_size)
out = out.reshape(out.shape[0], -1)
# Decode the hidden state of the last time step
out = self.fc(out)
return out
# Load Data
train_dataset = datasets.MNIST(root="dataset/", train=True, transform=transforms.ToTensor(), download=True)
test_dataset = datasets.MNIST(root="dataset/", train=False, transform=transforms.ToTensor(), download=True)
train_loader = DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=True)
# Initialize network (try out just using simple RNN, or GRU, and then compare with LSTM)
model = RNN_LSTM(input_size, hidden_size, num_layers, num_classes).to(device)
# Loss and optimizer
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)
# Train Network
for epoch in range(num_epochs):
for batch_idx, (data, targets) in enumerate(tqdm(train_loader)):
# Get data to cuda if possible
data = data.to(device=device).squeeze(1)
targets = targets.to(device=device)
# forward
scores = model(data)
loss = criterion(scores, targets)
# backward
optimizer.zero_grad()
loss.backward()
# gradient descent update step/adam step
optimizer.step()
# Check accuracy on training & test to see how good our model
def check_accuracy(loader, model):
num_correct = 0
num_samples = 0
# Set model to eval
model.eval()
with torch.no_grad():
for x, y in loader:
x = x.to(device=device).squeeze(1)
y = y.to(device=device)
scores = model(x)
_, predictions = scores.max(1)
num_correct += (predictions == y).sum()
num_samples += predictions.size(0)
# Toggle model back to train
model.train()
return num_correct / num_samples
print(f"Accuracy on training set: {check_accuracy(train_loader, model)*100:2f}")
print(f"Accuracy on test set: {check_accuracy(test_loader, model)*100:.2f}")

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"""
A simple walkthrough of how to code a convolutional neural network (CNN)
using the PyTorch library. For demonstration we train it on the very
common MNIST dataset of handwritten digits. In this code we go through
how to create the network as well as initialize a loss function, optimizer,
check accuracy and more.
Programmed by Aladdin Persson
* 2020-04-08: Initial coding
* 2021-03-24: More detailed comments and small revision of the code
"""
# Imports
import torch
import torchvision # torch package for vision related things
import torch.nn.functional as F # Parameterless functions, like (some) activation functions
import torchvision.datasets as datasets # Standard datasets
import torchvision.transforms as transforms # Transformations we can perform on our dataset for augmentation
from torch import optim # For optimizers like SGD, Adam, etc.
from torch import nn # All neural network modules
from torch.utils.data import DataLoader # Gives easier dataset managment by creating mini batches etc.
from tqdm import tqdm # For nice progress bar!
# Simple CNN
class CNN(nn.Module):
def __init__(self, in_channels=1, num_classes=10):
super(CNN, self).__init__()
self.conv1 = nn.Conv2d(
in_channels=in_channels,
out_channels=8,
kernel_size=(3, 3),
stride=(1, 1),
padding=(1, 1),
)
self.pool = nn.MaxPool2d(kernel_size=(2, 2), stride=(2, 2))
self.conv2 = nn.Conv2d(
in_channels=8,
out_channels=16,
kernel_size=(3, 3),
stride=(1, 1),
padding=(1, 1),
)
self.fc1 = nn.Linear(16 * 7 * 7, num_classes)
def forward(self, x):
x = F.relu(self.conv1(x))
x = self.pool(x)
x = F.relu(self.conv2(x))
x = self.pool(x)
x = x.reshape(x.shape[0], -1)
x = self.fc1(x)
return x
# Set device
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
# Hyperparameters
in_channels = 1
num_classes = 10
learning_rate = 0.001
batch_size = 64
num_epochs = 3
# Load Data
train_dataset = datasets.MNIST(root="dataset/", train=True, transform=transforms.ToTensor(), download=True)
test_dataset = datasets.MNIST(root="dataset/", train=False, transform=transforms.ToTensor(), download=True)
train_loader = DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=True)
# Initialize network
model = CNN(in_channels=in_channels, num_classes=num_classes).to(device)
# Loss and optimizer
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)
# Train Network
for epoch in range(num_epochs):
for batch_idx, (data, targets) in enumerate(tqdm(train_loader)):
# Get data to cuda if possible
data = data.to(device=device)
targets = targets.to(device=device)
# forward
scores = model(data)
loss = criterion(scores, targets)
# backward
optimizer.zero_grad()
loss.backward()
# gradient descent or adam step
optimizer.step()
# Check accuracy on training & test to see how good our model
def check_accuracy(loader, model):
num_correct = 0
num_samples = 0
model.eval()
with torch.no_grad():
for x, y in loader:
x = x.to(device=device)
y = y.to(device=device)
scores = model(x)
_, predictions = scores.max(1)
num_correct += (predictions == y).sum()
num_samples += predictions.size(0)
model.train()
return num_correct/num_samples
print(f"Accuracy on training set: {check_accuracy(train_loader, model)*100:.2f}")
print(f"Accuracy on test set: {check_accuracy(test_loader, model)*100:.2f}")

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"""
A simple walkthrough of how to code a fully connected neural network
using the PyTorch library. For demonstration we train it on the very
common MNIST dataset of handwritten digits. In this code we go through
how to create the network as well as initialize a loss function, optimizer,
check accuracy and more.
Programmed by Aladdin Persson
* 2020-04-08: Initial coding
* 2021-03-24: Added more detailed comments also removed part of
check_accuracy which would only work specifically on MNIST.
"""
# Imports
import torch
import torchvision # torch package for vision related things
import torch.nn.functional as F # Parameterless functions, like (some) activation functions
import torchvision.datasets as datasets # Standard datasets
import torchvision.transforms as transforms # Transformations we can perform on our dataset for augmentation
from torch import optim # For optimizers like SGD, Adam, etc.
from torch import nn # All neural network modules
from torch.utils.data import DataLoader # Gives easier dataset managment by creating mini batches etc.
from tqdm import tqdm # For nice progress bar!
# Here we create our simple neural network. For more details here we are subclassing and
# inheriting from nn.Module, this is the most general way to create your networks and
# allows for more flexibility. I encourage you to also check out nn.Sequential which
# would be easier to use in this scenario but I wanted to show you something that
# "always" works.
class NN(nn.Module):
def __init__(self, input_size, num_classes):
super(NN, self).__init__()
# Our first linear layer take input_size, in this case 784 nodes to 50
# and our second linear layer takes 50 to the num_classes we have, in
# this case 10.
self.fc1 = nn.Linear(input_size, 50)
self.fc2 = nn.Linear(50, num_classes)
def forward(self, x):
"""
x here is the mnist images and we run it through fc1, fc2 that we created above.
we also add a ReLU activation function in between and for that (since it has no parameters)
I recommend using nn.functional (F)
"""
x = F.relu(self.fc1(x))
x = self.fc2(x)
return x
# Set device cuda for GPU if it's available otherwise run on the CPU
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
# Hyperparameters of our neural network which depends on the dataset, and
# also just experimenting to see what works well (learning rate for example).
input_size = 784
num_classes = 10
learning_rate = 0.001
batch_size = 64
num_epochs = 3
# Load Training and Test data
train_dataset = datasets.MNIST(root="dataset/", train=True, transform=transforms.ToTensor(), download=True)
test_dataset = datasets.MNIST(root="dataset/", train=False, transform=transforms.ToTensor(), download=True)
train_loader = DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=True)
# Initialize network
model = NN(input_size=input_size, num_classes=num_classes).to(device)
# Loss and optimizer
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)
# Train Network
for epoch in range(num_epochs):
for batch_idx, (data, targets) in enumerate(tqdm(train_loader)):
# Get data to cuda if possible
data = data.to(device=device)
targets = targets.to(device=device)
# Get to correct shape
data = data.reshape(data.shape[0], -1)
# forward
scores = model(data)
loss = criterion(scores, targets)
# backward
optimizer.zero_grad()
loss.backward()
# gradient descent or adam step
optimizer.step()
# Check accuracy on training & test to see how good our model
def check_accuracy(loader, model):
num_correct = 0
num_samples = 0
model.eval()
with torch.no_grad():
for x, y in loader:
x = x.to(device=device)
y = y.to(device=device)
x = x.reshape(x.shape[0], -1)
scores = model(x)
_, predictions = scores.max(1)
num_correct += (predictions == y).sum()
num_samples += predictions.size(0)
model.train()
return num_correct/num_samples
print(f"Accuracy on training set: {check_accuracy(train_loader, model)*100:.2f}")
print(f"Accuracy on test set: {check_accuracy(test_loader, model)*100:.2f}")