utils.py

import numpy as np
import torch
from torch.autograd import Variable
import torchvision.transforms as transforms
from collections import defaultdict


class AvgrageMeter(object):
    def __init__(self):
        self.reset()

    def reset(self):
        self.avg = 0
        self.sum = 0
        self.cnt = 0

    def update(self, val, n=1):
        self.sum += val * n
        self.cnt += n
        self.avg = self.sum / self.cnt


class Cutout(object):
    def __init__(self, length):
        self.length = length

    def __call__(self, img):
        h, w = img.size(1), img.size(2)
        mask = np.ones((h, w), np.float32)
        y = np.random.randint(h)
        x = np.random.randint(w)

        y1 = np.clip(y - self.length // 2, 0, h)
        y2 = np.clip(y + self.length // 2, 0, h)
        x1 = np.clip(x - self.length // 2, 0, w)
        x2 = np.clip(x + self.length // 2, 0, w)

        mask[y1: y2, x1: x2] = 0.
        mask = torch.from_numpy(mask)
        mask = mask.expand_as(img)
        img *= mask
        return img


def accuracy(output, label, topk=(1,)):
    maxk = max(topk)
    batch_size = label.size(0)

    _, pred = output.topk(maxk, 1, True, True)
    pred = pred.t()
    correct = pred.eq(label.view(1, -1).expand_as(pred))

    res = []
    for k in topk:
        correct_k = correct[:k].view(-1).float().sum(0)
        res.append(correct_k.mul_(100.0 / batch_size))
    return res


def data_transforms_cifar(args):
    assert args.dataset in ['cifar10', 'imagenet']
    if args.dataset == 'cifar10':
        MEAN = [0.49139968, 0.48215827, 0.44653124]
        STD = [0.24703233, 0.24348505, 0.26158768]
    elif args.dataset == 'imagenet':
        MEAN = [0.485, 0.456, 0.406]
        STD = [0.229, 0.224, 0.225]

    if args.dataset == 'cifar10':
        train_transform = transforms.Compose([
            transforms.RandomCrop(32, padding=4),
            transforms.RandomHorizontalFlip(),
            # transforms.ColorJitter(brightness=0.4, contrast=0.4, saturation=0.4, hue=0.2),
            transforms.ToTensor(),
            transforms.Normalize(MEAN, STD)
        ])
        valid_transform = transforms.Compose([
            transforms.ToTensor(),
            transforms.Normalize(MEAN, STD)
        ])
    elif args.dataset == 'imagenet':
        train_transform = transforms.Compose([
            transforms.RandomResizedCrop(224),
            transforms.RandomHorizontalFlip(),
            transforms.ColorJitter(brightness=0.4, contrast=0.4, saturation=0.4, hue=0.2),
            transforms.ToTensor(),
            transforms.Normalize(MEAN, STD)
        ])
        valid_transform = transforms.Compose([
            transforms.Resize(256),
            transforms.CenterCrop(224),
            transforms.ToTensor(),
            transforms.Normalize(MEAN, STD)
        ])

    if args.cutout:
        train_transform.transforms.append(Cutout(args.cutout_length))

    return train_transform, valid_transform


def get_variable(inputs, cuda=False, **kwargs):
    if type(inputs) in [list, np.ndarray]:
        inputs = torch.Tensor(inputs)
    if cuda:
        out = Variable(inputs.cuda(), **kwargs)
    else:
        out = Variable(inputs, **kwargs)
    return out


class keydefaultdict(defaultdict):
    def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(key)
            return ret


class PrefetchedWrapper(object):
    def prefetched_loader(loader):
        stream = torch.cuda.Stream()
        first = True

        for next_input, next_target in loader:
            with torch.cuda.stream(stream):
                next_input = next_input.cuda(async=True)
                next_target = next_target.cuda(async=True)
                next_input = next_input.float()

            if not first:
                yield input, target
            else:
                first = False

            torch.cuda.current_stream().wait_stream(stream)
            input = next_input
            target = next_target

        yield input, target

    def __init__(self, dataloader):
        self.dataloader = dataloader
        self.epoch = 0

    def __iter__(self):
        if (self.dataloader.sampler is not None and
            isinstance(self.dataloader.sampler,
                       torch.utils.data.distributed.DistributedSampler)):

            self.dataloader.sampler.set_epoch(self.epoch)
        self.epoch += 1
        return PrefetchedWrapper.prefetched_loader(self.dataloader)