classifier_model.py

'''
https://github.com/kuangliu/pytorch-cifar

ResNet in PyTorch.

For Pre-activation ResNet, see 'preact_resnet.py'.

Reference:
[1] Kaiming He, Xiangyu Zhang, Shaoqing Ren, Jian Sun
    Deep Residual Learning for Image Recognition. arXiv:1512.03385
'''
from collections import OrderedDict
from tqdm import tqdm
import torch
from torch import nn
from torch.nn import functional as F
from matplotlib import pyplot as plt
from torchsummary import summary
import pandas as pd
from torch_lr_finder import LRFinder


train_losses = []
test_losses = []
train_acc = []
test_acc = []


class BasicBlock(nn.Module):
    expansion = 1

    def __init__(self, in_planes, planes, stride=1):
        super(BasicBlock, self).__init__()
        self.conv1 = nn.Conv2d(
            in_planes, planes, kernel_size=3, stride=stride, padding=1, bias=False)
        self.bn1 = nn.BatchNorm2d(planes)
        self.conv2 = nn.Conv2d(planes, planes, kernel_size=3,
                               stride=1, padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(planes)

        self.shortcut = nn.Sequential()
        if stride != 1 or in_planes != self.expansion*planes:
            self.shortcut = nn.Sequential(
                nn.Conv2d(in_planes, self.expansion*planes,
                          kernel_size=1, stride=stride, bias=False),
                nn.BatchNorm2d(self.expansion*planes)
            )

    def forward(self, x):
        out = F.relu(self.bn1(self.conv1(x)))
        out = self.bn2(self.conv2(out))
        out += self.shortcut(x)
        out = F.relu(out)
        return out

class ResNet(nn.Module):
    def __init__(self, block, num_blocks, num_classes=10):
        super(ResNet, self).__init__()
        self.in_planes = 64

        self.conv1 = nn.Conv2d(3, 64, kernel_size=3,
                               stride=1, padding=1, bias=False)
        self.bn1 = nn.BatchNorm2d(64)
        self.layer1 = self._make_layer(block, 64, num_blocks[0], stride=1)
        self.layer2 = self._make_layer(block, 128, num_blocks[1], stride=2)
        self.layer3 = self._make_layer(block, 256, num_blocks[2], stride=2)
        self.layer4 = self._make_layer(block, 512, num_blocks[3], stride=2)
        self.linear = nn.Linear(512*block.expansion, num_classes)

    def _make_layer(self, block, planes, num_blocks, stride):
        strides = [stride] + [1]*(num_blocks-1)
        layers = []
        for stride in strides:
            layers.append(block(self.in_planes, planes, stride))
            self.in_planes = planes * block.expansion
        return nn.Sequential(*layers)

    def forward(self, x):
        out = F.relu(self.bn1(self.conv1(x)))
        out = self.layer1(out)
        out = self.layer2(out)
        out = self.layer3(out)
        out = self.layer4(out)
        out = F.avg_pool2d(out, 4)
        out = out.view(out.size(0), -1)
        out = self.linear(out)
        return out


def ResNet18():
    return ResNet(BasicBlock, [2, 2, 2, 2])



def plot_loss_n_acc(writer):
    """
    plots the train and test
    losses and accuracies
    Parameters
    ----------
    losses : (train_losses, test_losses)
        train and test losses values for each batch
    accuracies : (train_acc, test_acc)
        train and test accuracy values for each batch
    """
    # performance and loss curves
    fig, axs = plt.subplots(2, 2, figsize=(15,10))
    axs[0, 0].plot(train_losses)
    axs[0, 0].set_title("Training Loss")
    axs[1, 0].plot(train_acc)
    axs[1, 0].set_title("Training Accuracy")
    axs[0, 1].plot(test_losses)
    axs[0, 1].set_title("Test Loss")
    axs[1, 1].plot(test_acc)
    axs[1, 1].set_title("Test Accuracy")
    writer.add_figure('performance curves', fig)

def summary_printer(model, device='cpu'):
    model = model.to(device)
    return summary(model, input_size=(3, 28, 28))