utils.py

import logging
import os, shutil, torch
import numpy as np
import torch.nn as nn
import torch.nn.functional as F


def darts_weight_unpack(weight, n_nodes):
    w_dag = []
    start_index = 0
    end_index = 2
    for i in range(n_nodes):
        w_dag.append(weight[start_index:end_index])
        start_index = end_index
        end_index += 3 + i
    return w_dag


def one_hot_to_index(one_hot_matrix):
    return np.array([np.where(r == 1)[0][0] for r in one_hot_matrix])


def index_to_one_hot(index_vector, C):
    return np.eye(C)[index_vector.reshape(-1)]


def get_logger(file_path):
    """ Make python logger """
    # [!] Since tensorboardX use default logger (e.g. logging.info()), we should use custom logger
    logger = logging.getLogger('darts')
    log_format = '%(asctime)s | %(message)s'
    formatter = logging.Formatter(log_format, datefmt='%m/%d %I:%M:%S %p')
    file_handler = logging.FileHandler(file_path)
    file_handler.setFormatter(formatter)
    stream_handler = logging.StreamHandler()
    stream_handler.setFormatter(formatter)

    logger.addHandler(file_handler)
    logger.addHandler(stream_handler)
    logger.setLevel(logging.INFO)

    return logger


def accuracy(output, target, topk=(1,)):
    """ Computes the precision@k for the specified values of k """
    maxk = max(topk)
    batch_size = target.size(0)

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

    res = []
    for k in topk:
        correct_k = correct[:k].view(-1).float().sum(0, keepdim=True)
        res.append(correct_k.mul_(1.0 / batch_size))
    return res


def save_checkpoint(state, ckpt_dir, is_best=False):
    filename = os.path.join(ckpt_dir, 'checkpoint.pth.tar')
    torch.save(state, filename)
    if is_best:
        best_filename = os.path.join(ckpt_dir, 'best.pth.tar')
        shutil.copyfile(filename, best_filename)


def netParams(model):
    total_paramters = 0
    for parameter in model.parameters():
        i = len(parameter.size())
        p = 1
        for j in range(i):
            p *= parameter.size(j)
        total_paramters += p

    return total_paramters / 1024. /1024.


class AverageMeter(object):
    """
    Computes and stores the average and current value
    Copied from: https://github.com/pytorch/examples/blob/master/imagenet/main.py
    """

    def __init__(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

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


class LabelSmoothLoss(nn.Module):

    def __init__(self, smoothing=0.0):
        super(LabelSmoothLoss, self).__init__()
        self.smoothing = smoothing

    def forward(self, input, target):
        log_prob = F.log_softmax(input, dim=-1)
        weight = input.new_ones(input.size()) * \
                 self.smoothing / (input.size(-1) - 1.)
        weight.scatter_(-1, target.unsqueeze(-1), (1. - self.smoothing))
        loss = (-weight * log_prob).sum(dim=-1).mean()
        return loss