"""
# -*- coding: utf-8 -*-
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# Author: Nguyen Mau Dung
# DoC: 2020.08.09
# email: nguyenmaudung93.kstn@gmail.com
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# Description: some utilities of torch (conversion)
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"""

import torch
import torch.distributed as dist

__all__ = ['convert2cpu', 'convert2cpu_long', 'to_cpu', 'reduce_tensor', 'to_python_float', '_sigmoid']


def convert2cpu(gpu_matrix):
    return torch.FloatTensor(gpu_matrix.size()).copy_(gpu_matrix)


def convert2cpu_long(gpu_matrix):
    return torch.LongTensor(gpu_matrix.size()).copy_(gpu_matrix)


def to_cpu(tensor):
    return tensor.detach().cpu()


def reduce_tensor(tensor, world_size):
    rt = tensor.clone()
    dist.all_reduce(rt, op=dist.reduce_op.SUM)
    rt /= world_size
    return rt


def to_python_float(t):
    if hasattr(t, 'item'):
        return t.item()
    else:
        return t[0]


def _sigmoid(x):
    return torch.clamp(x.sigmoid_(), min=1e-4, max=1 - 1e-4)