Why is my pytorch classification model not learning? - machine-learning

I have created a simple pytorch classification model with sample datasets generated using sklearns make_classification. Even after training for thousands of epochs the accuracy of the model hovers between 30 and 40 percentage. During training itself the loss value is fluctuating very far and wide. I am wondering why this model is not learning, whether it's due to some logical error in the code.
import torch
from torch.utils.data import Dataset, DataLoader
import torch.nn as nn
from sklearn.datasets import make_classification
from sklearn.model_selection import train_test_split
X,y = make_classification(n_features=15,n_classes=5,n_informative=4)
DEVICE = torch.device('cuda')
epochs = 5000
class CustomDataset(Dataset):
def __init__(self,X,y):
self.X = torch.from_numpy(X)
self.y = torch.from_numpy(y)
def __len__(self):
return len(self.X)
def __getitem__(self, index):
X = self.X[index]
y = self.y[index]
return (X,y)
class Model(nn.Module):
def __init__(self):
super().__init__()
self.l1 = nn.Linear(15,10)
self.l2 = nn.Linear(10,5)
self.relu = nn.ReLU()
def forward(self,x):
x = self.l1(x)
x = self.relu(x)
x = self.l2(x)
x = self.relu(x)
return x
model = Model().double().to(DEVICE)
optimizer = torch.optim.Adam(model.parameters(), lr=0.001)
loss_function = nn.CrossEntropyLoss()
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.33, random_state=42)
train_data = CustomDataset(X_train,y_train)
test_data = CustomDataset(X_test,y_test)
trainloader = DataLoader(train_data, batch_size=32, shuffle=True)
testloader = DataLoader(test_data, batch_size=32, shuffle=True)
for i in range(epochs):
for (x,y) in trainloader:
x = x.to(DEVICE)
y = y.to(DEVICE)
optimizer.zero_grad()
output = model(x)
loss = loss_function(output,y)
loss.backward()
optimizer.step()
if i%200==0:
print("epoch: ",i," Loss: ",loss.item())
correct = 0
total = 0
# since we're not training, we don't need to calculate the gradients for our outputs
with torch.no_grad():
for x, y in testloader:
# calculate outputs by running x through the network
outputs = model(x.to(DEVICE)).to(DEVICE)
# the class with the highest energy is what we choose as prediction
_, predicted = torch.max(outputs.data, 1)
total += y.size(0)
correct += (predicted == y.to(DEVICE)).sum().item()
print(f'Accuracy of the network on the test data: {100 * correct // total} %')
EDIT
I tried to over-fit my model with only 10 samples (batch_size=5) X,y = make_classification(n_samples=10,n_features=15,n_classes=5,n_informative=4) but now the accuracy decreased to 15-20%. I then normalize the input data between the values 0 and 1 which pushed the accuracy a bit higher but not over 50 percentage. Any idea why this might be happening?

You should not be using ReLU activation on your output layer. Usually softmax activation is used for multi class classification on the final layer, or the logits are fed to the loss function directly without explicitly adding a softmax activation layer.
Try removing the ReLU activation from the final layer.

Related

Pytorch LSTM Prediction not learning

I'm using a LSTM model to predict BABA stock price using this dataset: "/kaggle/input/price-volume-data-for-all-us-stocks-etfs/Data/Stocks/baba.us.txt".
I'm not sure why my model is not learning and the y_test_prediction is so different from the actual y_test. I really appreciate your help as I'm beginning to learn machine learning. Thank you!
I have scaled the data with minMaxScaler before splitting it. This is how I split the data:
x_train, y_train, x_test, y_test = [], [], [], []
lags = 3
for t in range(len(train_data)-lags-1):
x_train.append(train_data[t:(t+lags),:])
y_train.append(train_data[(t+lags),:])
for t in range(len(test_data)-lags-1):
x_test.append(test_data[t:(t+lags),:])
y_test.append(test_data[(t+lags),:])
x_train = torch.FloatTensor(np.array(x_train))
y_train = torch.FloatTensor(np.array(y_train))
x_test = torch.FloatTensor(np.array(x_test))
y_test = torch.FloatTensor(np.array(y_test))
x_train = np.reshape(x_train,(x_train.shape[0],x_train.shape[1],1))
x_test = np.reshape(x_test,(x_test.shape[0],x_test.shape[1],1))
print(x_train.shape)
print(y_train.shape)
print(x_test.shape)
print(y_test.shape)
This is my LSTM model:
input_dim = 1
hidden_layer_dim = 32
num_layers = 1
output_dim = 1
class LSTM(nn.Module):
def __init__(self, input_dim,hidden_layer_dim, num_layers, output_dim ):
super(LSTM, self).__init__()
self.input_dim = input_dim
self.hidden_layer_dim = hidden_layer_dim
self.num_layers = num_layers
self.output_dim = output_dim
self.lstm = nn.LSTM(input_dim, hidden_layer_dim,num_layers,batch_first = True)
self.fc = nn.Linear(hidden_layer_dim, output_dim)
def forward(self, x):
# initial hidden state & cell state as zeros
h0 = Variable(torch.zeros(self.num_layers, x.size(0), self.hidden_layer_dim))
c0 = Variable(torch.zeros(self.num_layers, x.size(0), self.hidden_layer_dim))
# lstm output with hidden and cell state
output, (hn, cn) = self.lstm(x, (h0,c0))
# get hidden state to be passed to dense layer
hn = hn.view(-1, self.hidden_layer_dim)
output = self.fc(hn)
return output
This is my training:
num_epochs = 100
learning_rate = 0.01
model = LSTM(input_dim,hidden_layer_dim, num_layers, output_dim)
loss = torch.nn.MSELoss() # mean-squared error for regression
optimizer = torch.optim.Adam(model.parameters(), lr=learning_rate)
hist = np.zeros(num_epochs)
# train model
for epoch in range(num_epochs):
outputs = model(x_train)
optimizer.zero_grad()
#get loss function
loss_fn = loss(outputs, y_train.view(1,-1))
hist[epoch] = loss_fn.item()
loss_fn.backward()
optimizer.step()
if epoch %10==0:
print("Epoch: %d, loss: %1.5f" % (epoch, hist[epoch]))
This is the training loss and prediction vs actual
training loss
prediction vs actual
You are initialising hidden layers every time forward is being called, which might cause errors with backprop. You do not even have to initialise them. PyTorch takes care of that for you. You can check this implementation for the details. Also, as a side note, you might want to take a look at PyTorch dataloaders(just an easier way to make splits).

How to fix this loss is NaN problem in PyTorch of this RNN with GRU?

I'm completely new to PyTorch and tried out some models. I wanted to make an easy prediction rnn of stock market prices and found the following code:
I load the data set with pandas then split it into training and test data and load it into a pytorch DataLoader for later usage in training process. The model is defined in the GRU class. But the actual problem seems to be the optimisation. I think the problem could be gradient explosion. I thought about adding gradient clipping but the GRU design should actually prevent gradient explosion or am I wrong? What could cause the loss to be instantly NaN (already in the first epoch)
from sklearn.preprocessing import MinMaxScaler
import time
import pandas as pd
import numpy as np
import torch
import torch.nn as nn
from torch.utils.data import TensorDataset, DataLoader
batch_size = 200
input_dim = 1
hidden_dim = 32
num_layers = 2
output_dim = 1
num_epochs = 10
nvda = pd.read_csv('dataset/stocks/NVDA.csv')
price = nvda[['Close']]
scaler = MinMaxScaler(feature_range=(-1, 1))
price['Close'] = scaler.fit_transform(price['Close'].values.reshape(-1, 1))
def split_data(stock, lookback):
data_raw = stock.to_numpy() # convert to numpy array
data = []
# create all possible sequences of length seq_len
for index in range(len(data_raw) - lookback):
data.append(data_raw[index: index + lookback])
data = np.array(data)
test_set_size = int(np.round(0.2 * data.shape[0]))
train_set_size = data.shape[0] - (test_set_size)
x_train = data[:train_set_size, :-1, :]
y_train = data[:train_set_size, -1, :]
x_test = data[train_set_size:, :-1]
y_test = data[train_set_size:, -1, :]
return [x_train, y_train, x_test, y_test]
lookback = 20 # choose sequence length
x_train, y_train, x_test, y_test = split_data(price, lookback)
train_data = TensorDataset(torch.from_numpy(x_train).float(), torch.from_numpy(y_train).float())
train_data = DataLoader(train_data, shuffle=True, batch_size=batch_size, drop_last=True)
test_data = TensorDataset(torch.from_numpy(x_test).float(), torch.from_numpy(y_test).float())
test_data = DataLoader(test_data, shuffle=True, batch_size=batch_size, drop_last=True)
class GRU(nn.Module):
def __init__(self, input_dim, hidden_dim, num_layers, output_dim):
super(GRU, self).__init__()
self.hidden_dim = hidden_dim
self.num_layers = num_layers
self.gru = nn.GRU(input_dim, hidden_dim, num_layers, batch_first=True, dropout=0.2)
self.fc = nn.Linear(hidden_dim, output_dim)
self.relu = nn.ReLU()
def forward(self, x, h):
out, h = self.gru(x, h)
out = self.fc(self.relu(out[:, -1]))
return out, h
def init_hidden(self, batch_size):
weight = next(self.parameters()).data
hidden = weight.new(self.num_layers, batch_size, self.hidden_dim).zero_()
return hidden
model = GRU(input_dim=input_dim, hidden_dim=hidden_dim, output_dim=output_dim, num_layers=num_layers)
criterion = nn.MSELoss()
optimizer = torch.optim.Adam(model.parameters(), lr=0.0000000001)
model.train()
start_time = time.time()
h = model.init_hidden(batch_size)
for epoch in range(1, num_epochs+1):
for x, y in train_data:
h = h.data
model.zero_grad()
y_train_pred, h = model(x, h)
loss = criterion(y_train_pred, y)
print("Epoch ", epoch, "MSE: ", loss.item())
loss.backward()
optimizer.step()
training_time = time.time() - start_time
print("Training time: {}".format(training_time))
This is the dataset which I used.
Not sure if it is the case, but did you preprocess and cleaned the data? I do not know it but maybe there are some values missing or it's something strange about it. I checked it here
https://ca.finance.yahoo.com/quote/NVDA/history?p=NVDA and it seems that every couple of rows there is some inconsistency. Like I said, I do not know if it's the case but it may be.

Size Mismatch using pytorch when trying to train data

I am really new to pytorch and just trying to use my own dataset to do a simple Linear Regression Model. I am only using the numbers values as inputs, too.
I have imported the data from the CSV
dataset = pd.read_csv('mlb_games_overview.csv')
I have split the data into four parts X_train, X_test, y_train, y_test
X = dataset.drop(['date', 'team', 'runs', 'win'], 1)
y = dataset['win']
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3, random_state=True)
I have converted the data to pytorch tensors
X_train = torch.from_numpy(np.array(X_train))
X_test = torch.from_numpy(np.array(X_test))
y_train = torch.from_numpy(np.array(y_train))
y_test = torch.from_numpy(np.array(y_test))
I have created a LinearRegressionModel
class LinearRegressionModel(torch.nn.Module):
def __init__(self):
super(LinearRegressionModel, self).__init__()
self.linear = torch.nn.Linear(1, 1)
def forward(self, x):
y_pred = self.linear(x)
return y_pred
I have initialized the optimizer and the loss function
criterion = torch.nn.MSELoss(reduction='sum')
optimizer = torch.optim.SGD(model.parameters(), lr=0.01)
Now when I start to train the data I get the runtime error mismatch
EPOCHS = 500
for epoch in range(EPOCHS):
pred_y = model(X_train) # RUNTIME ERROR HERE
loss = criterion(pred_y, y_train)
optimizer.zero_grad() # zero out gradients to update parameters correctly
loss.backward() # backpropagation
optimizer.step() # update weights
print('epoch {}, loss {}'. format(epoch, loss.data[0]))
Error Log:
RuntimeError Traceback (most recent call last)
<ipython-input-40-c0474231d515> in <module>
1 EPOCHS = 500
2 for epoch in range(EPOCHS):
----> 3 pred_y = model(X_train)
4 loss = criterion(pred_y, y_train)
5 optimizer.zero_grad() # zero out gradients to update parameters correctly
RuntimeError: size mismatch, m1: [3540 x 8], m2: [1 x 1] at
C:\w\1\s\windows\pytorch\aten\src\TH/generic/THTensorMath.cpp:752
In your Linear Regression model, you have:
self.linear = torch.nn.Linear(1, 1)
But your training data (X_train) shape is 3540 x 8 which means you have 8 features representing each input example. So, you should define the linear layer as follows.
self.linear = torch.nn.Linear(8, 1)
A linear layer in PyTorch has parameters, W and b. If you set the in_features to 8 and out_features to 1, then the shape of the W matrix will be 1 x 8 and the length of b vector will be 1.
Since your training data shape is 3540 x 8, you can perform the following operation.
linear_out = X_train W_T + b
I hope it clarifies your confusion.

Test set accuracy is very high after very few epochs on mnist dataset

With very few epochs this model learns to classify beween 1 and 0 extremely quickly which leads me to consider something is wrong.
Below code downloads mnist dataset, extracts the mnist images that contain 1 or 0 only. A random sample of size 200 is selected from this subset of mnist images. This random sample is the dataset the model is trained on. With just 2 epochs the model achieves 90%+ test set accuracy, is this expected behaviour ? I expected many more epochs would be required in order to train the model to achieve this level of test set accuracy.
Model code :
%reset -f
import torch
import torch.nn as nn
import torchvision
import torchvision.transforms as transforms
import torch
import torch.nn as nn
import torchvision
import torchvision.transforms as transforms
import torch.utils.data as data_utils
import numpy as np
import matplotlib.pyplot as plt
from sklearn.datasets import make_moons
from matplotlib import pyplot
from pandas import DataFrame
import torchvision.datasets as dset
import os
import torch.nn.functional as F
import time
import random
import pickle
from sklearn.metrics import confusion_matrix
import pandas as pd
import sklearn
trans = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
root = './data'
if not os.path.exists(root):
os.mkdir(root)
train_set = dset.MNIST(root=root, train=True, transform=trans, download=True)
test_set = dset.MNIST(root=root, train=False, transform=trans, download=True)
batch_size = 64
train_loader = torch.utils.data.DataLoader(
dataset=train_set,
batch_size=batch_size,
shuffle=True)
test_loader = torch.utils.data.DataLoader(
dataset=test_set,
batch_size=batch_size,
shuffle=True)
class NeuralNet(nn.Module):
def __init__(self):
super(NeuralNet, self).__init__()
self.fc1 = nn.Linear(28*28, 500)
self.fc2 = nn.Linear(500, 256)
self.fc3 = nn.Linear(256, 2)
def forward(self, x):
x = x.view(-1, 28*28)
x = F.relu(self.fc1(x))
x = F.relu(self.fc2(x))
x = self.fc3(x)
return x
num_epochs = 2
random_sample_size = 200
values_0_or_1 = [t for t in train_set if (int(t[1]) == 0 or int(t[1]) == 1)]
values_0_or_1_testset = [t for t in test_set if (int(t[1]) == 0 or int(t[1]) == 1)]
print(len(values_0_or_1))
print(len(values_0_or_1_testset))
train_loader_subset = torch.utils.data.DataLoader(
dataset=values_0_or_1,
batch_size=batch_size,
shuffle=True)
test_loader_subset = torch.utils.data.DataLoader(
dataset=values_0_or_1_testset,
batch_size=batch_size,
shuffle=False)
train_loader = train_loader_subset
# Hyper-parameters
input_size = 100
hidden_size = 100
num_classes = 2
# learning_rate = 0.00001
learning_rate = .0001
# Device configuration
device = 'cpu'
print_progress_every_n_epochs = 1
model = NeuralNet().to(device)
# Loss and optimizer
criterion = nn.CrossEntropyLoss()
optimizer = torch.optim.Adam(model.parameters(), lr=learning_rate)
N = len(train_loader)
# Train the model
total_step = len(train_loader)
most_recent_prediction = []
test_actual_predicted_dict = {}
rm = random.sample(list(values_0_or_1), random_sample_size)
train_loader_subset = data_utils.DataLoader(rm, batch_size=4)
for epoch in range(num_epochs):
for i, (images, labels) in enumerate(train_loader_subset):
# Move tensors to the configured device
images = images.reshape(-1, 2).to(device)
labels = labels.to(device)
# Forward pass
outputs = model(images)
loss = criterion(outputs, labels)
# Backward and optimize
optimizer.zero_grad()
loss.backward()
optimizer.step()
if (epoch) % print_progress_every_n_epochs == 0:
print ('Epoch [{}/{}], Step [{}/{}], Loss: {:.4f}'.format(epoch+1, num_epochs, i+1, total_step, loss.item()))
predicted_test = []
model.eval() # eval mode (batchnorm uses moving mean/variance instead of mini-batch mean/variance)
probs_l = []
predicted_values = []
actual_values = []
labels_l = []
with torch.no_grad():
for images, labels in test_loader_subset:
images = images.to(device)
labels = labels.to(device)
outputs = model(images)
_, predicted = torch.max(outputs.data, 1)
predicted_test.append(predicted.cpu().numpy())
sm = torch.nn.Softmax()
probabilities = sm(outputs)
probs_l.append(probabilities)
labels_l.append(labels.cpu().numpy())
predicted_values.append(np.concatenate(predicted_test).ravel())
actual_values.append(np.concatenate(labels_l).ravel())
if (epoch) % 1 == 0:
print('test accuracy : ', 100 * len((np.where(np.array(predicted_values[0])==(np.array(actual_values[0])))[0])) / len(actual_values[0]))
Output of model (12665 & 2115 represents the training and test set sizes) :
12665
2115
Epoch [1/2], Step [50/198], Loss: 0.1256
Epoch [2/2], Step [50/198], Loss: 0.0151
test accuracy : 99.76359338061465
/anaconda3/envs/pytorch/lib/python3.7/site-packages/ipykernel_launcher.py:143: UserWarning: Implicit dimension choice for softmax has been deprecated. Change the call to include dim=X as an argument.
Here's my 2 cents on your binary experiment.
It would seem like you have severely reduce the complexity of your dataset and with the high number of neurons in your intermediate layers, your model is expected to converge very quickly.
Note that MNIST dataset has channel of 1 and this makes the task very simple.
You may try to play with CIFAR10 and see if you are still getting high accuracy in just 2 epochs.
That's not a particularly well-posed question, because what is expected is entirely subjective. That being said, I am not surprised because 0 and 1 are very different digits. For instance, 0 has background surrounded by foreground, whereas 1 does not - that's an almost infallible test to distinguish the two. As a sanity check, I would swap out 0 for 7, which is similar to 1. I would expect to see significantly lower success rate. That being said, that's a sanity check - even if it passes, there may still be bugs or errors in your method.

Problems with PyTorch MLP when training the MNIST dataset retrieved from Keras

I have finished a PyTorch MLP model for the MNIST dataset, but got two different results: 0.90+ accuracy when using MNIST dataset from PyTorch, but ~0.10 accuracy when using MNIST dataset from Keras.
Below is my code with dependency: PyTorch 0.3.0.post4, keras 2.1.3, tensorflow backend 1.4.1 gpu version.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import numpy as np
import torch as pt
import torchvision as ptv
from keras.datasets import mnist
from torch.nn import functional as F
from torch.utils.data import Dataset, DataLoader
# training data from PyTorch
train_set = ptv.datasets.MNIST("./data/mnist/train", train=True, transform=ptv.transforms.ToTensor(), download=True)
test_set = ptv.datasets.MNIST("./data/mnist/test", train=False, transform=ptv.transforms.ToTensor(), download=True)
train_dataset = DataLoader(train_set, batch_size=100, shuffle=True)
test_dataset = DataLoader(test_set, batch_size=10000, shuffle=True)
class MLP(pt.nn.Module):
"""The Multi-layer perceptron"""
def __init__(self):
super(MLP, self).__init__()
self.fc1 = pt.nn.Linear(784, 512)
self.fc2 = pt.nn.Linear(512, 128)
self.fc3 = pt.nn.Linear(128, 10)
self.use_gpu = True
def forward(self, din):
din = din.view(-1, 28 * 28)
dout = F.relu(self.fc1(din))
dout = F.relu(self.fc2(dout))
# return F.softmax(self.fc3(dout))
return self.fc3(dout)
model = MLP().cuda()
print(model)
# loss func and optim
optimizer = pt.optim.SGD(model.parameters(), lr=1)
criterion = pt.nn.CrossEntropyLoss().cuda()
def evaluate_acc(pred, label):
pred = pred.cpu().data.numpy()
label = label.cpu().data.numpy()
test_np = (np.argmax(pred, 1) == label)
test_np = np.float32(test_np)
return np.mean(test_np)
def evaluate_loader(loader):
print("evaluating ...")
accurarcy_list = []
for i, (inputs, labels) in enumerate(loader):
inputs = pt.autograd.Variable(inputs).cuda()
labels = pt.autograd.Variable(labels).cuda()
outputs = model(inputs)
accurarcy_list.append(evaluate_acc(outputs, labels))
print(sum(accurarcy_list) / len(accurarcy_list))
def training(d, epochs):
for x in range(epochs):
for i, data in enumerate(d):
optimizer.zero_grad()
(inputs, labels) = data
inputs = pt.autograd.Variable(inputs).cuda()
labels = pt.autograd.Variable(labels).cuda()
outputs = model(inputs)
loss = criterion(outputs, labels)
loss.backward()
optimizer.step()
if i % 200 == 0:
print(i, ":", evaluate_acc(outputs, labels))
# Training MLP for 4 epochs with MNIST dataset from PyTorch
training(train_dataset, 4)
# The accuracy is ~0.96.
evaluate_loader(test_dataset)
print("###########################################################")
def load_mnist():
(x, y), (x_test, y_test) = mnist.load_data()
x = x.reshape((-1, 1, 28, 28)).astype(np.float32)
x_test = x_test.reshape((-1, 1, 28, 28)).astype(np.float32)
y = y.astype(np.int64)
y_test = y_test.astype(np.int64)
print("x.shape", x.shape, "y.shape", y.shape,
"\nx_test.shape", x_test.shape, "y_test.shape", y_test.shape,
)
return x, y, x_test, y_test
class TMPDataset(Dataset):
"""Dateset for loading Keras MNIST dataset."""
def __init__(self, a, b):
self.x = a
self.y = b
def __getitem__(self, item):
return self.x[item], self.y[item]
def __len__(self):
return len(self.y)
x_train, y_train, x_test, y_test = load_mnist()
# Create dataloader for MNIST dataset from Keras.
test_loader = DataLoader(TMPDataset(x_test, y_test), num_workers=1, batch_size=10000)
train_loader = DataLoader(TMPDataset(x_train, y_train), shuffle=True, batch_size=100)
# Evaluate the performance of MLP trained on PyTorch dataset and the accurach is ~0.96.
evaluate_loader(test_loader)
evaluate_loader(train_loader)
model = MLP().cuda()
print(model)
optimizer = pt.optim.SGD(model.parameters(), lr=1)
criterion = pt.nn.CrossEntropyLoss().cuda()
# Train now on MNIST dataset from Keras.
training(train_loader, 4)
# Evaluate the trianed model on MNIST dataset from Keras and result in performance ~0.10...
evaluate_loader(test_loader)
evaluate_loader(train_loader)
I had checked some samples from Keras MNIST dataset and found no error.
I am wondering what is wrong with the datasets?
The code can run without error, run it to see the results.
The MNIST data coming from Keras are not normalized; following the Keras MNIST MLP example, you should do it manually, i.e. you should include the following in your load_data() function:
x /= 255
x_test /= 255
Not sure about PyTorch, but it would seem that the MNIST data from their own utility functions come already normalized (as is the case with Tensorflow - see the third point in my answer here).
A 10% accuracy (i.e. equivalent to random guessing) in case of not-normalized input data is perfectly consistent.

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