def _warmup_update_lr(optimizer, epoch, init_lr, warmup_epochs, warmup_ratio=0.0):
    '\n    update learning rate of optimizers\n    '
    lr = ((((init_lr - warmup_ratio) * epoch) / warmup_epochs) + warmup_ratio)
    for param_group in optimizer.param_groups:
        param_group['lr'] = lr
    return lr
update learning rate of optimizers
def _warmup_update_lr(optimizer, epoch, init_lr, warmup_epochs, warmup_ratio=0.0):
    '\n    \n    '
    lr = ((((init_lr - warmup_ratio) * epoch) / warmup_epochs) + warmup_ratio)
    for param_group in optimizer.param_groups:
        param_group['lr'] = lr
    return lr