auto-tensor

Inspired by CSE-559W and PyTorch

Auto-tensor is an (toy) auto differentiation tool that helps me dive into back propagation and deep learning system. By constructing computation graph and defining some basic operation such as add, sub, mul, exp, log……, we can build our own deep learning system out of scratch (Numpy).

• auto_tensor.py define some useful helper functions and operations
• nn.py define neural network model and some common layers
• optim.py define optimizers
• tensor.py define main Tensor class using Numpy
• auto_tensor_test.py unittest file

Examples

1. Logistic Regression

Import packages that we need.

Here, sklearn is only used to generate dataset and evaluate our model.

import auto_tensor as at
from auto_tensor import nn
from auto_tensor import optim
from sklearn.datasets import load_breast_cancer
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
import numpy as np

Using some helper functions to help us define a logistic regression model

class LogisticRegression(nn.Module):

    def __init__(self, feature_num):
        self.linear = nn.Linear('linear', in_dim=feature_num, out_dim=1, bias=True)

    def forward(self, x):
        u = self.linear(x)
        y = at.sigmoid(u)
        return y

Training

epoch = 1000
lr = 0.1

model = LogisticRegression(X.shape[1])
optimizer = optim.SGD(model.params(), lr=lr)

for i in range(epoch):
    model.zero_grad()

    y_hat = model(X_train)
    # reshape y_train to (batch_size, 1)
    y_train_view = at.view(y_train, (y_train.shape[0], 1))  
    # calculate loss
    loss = at.binary_cross_entropy(y_hat, y_train_view)
    loss.backward()

    # take a step forward
    optimizer.step()

    if i % 100 == 0:
        y_predict_np = np.where(y_hat.data >= 0.5, 1, 0)
        train_acc = accuracy_score(y_train.data, y_predict_np)
        print('epoch: {}, loss: {}, train acc: {}'.format(i, loss, train_acc))

Finally, here is the final result for sklearn breast cancer dataset

epoch: 0, loss: tensor([[0.69314718]]), train acc: 0.6194225721784777
epoch: 100, loss: tensor([[0.10752918]]), train acc: 0.9816272965879265
epoch: 200, loss: tensor([[0.08930128]]), train acc: 0.9816272965879265
epoch: 300, loss: tensor([[0.08109473]]), train acc: 0.984251968503937
epoch: 400, loss: tensor([[0.07611094]]), train acc: 0.984251968503937
epoch: 500, loss: tensor([[0.07263933]]), train acc: 0.9868766404199475
epoch: 600, loss: tensor([[0.070022]]), train acc: 0.9868766404199475
epoch: 700, loss: tensor([[0.06794497]]), train acc: 0.9868766404199475
epoch: 800, loss: tensor([[0.06623663]]), train acc: 0.9868766404199475
epoch: 900, loss: tensor([[0.06479402]]), train acc: 0.9868766404199475

-------------start testing------------

test loss: tensor([[0.05554556]])
test acc: 0.9840425531914894