activation_mish.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-

"""
@Author: _defined
@Time:  2019/9/25 10:38
@Description: 
"""

import tensorflow as tf
from tensorflow.keras.layers import Activation
from tensorflow.keras.utils import get_custom_objects


class Mish(Activation):
    """
    Mish Activation Function.

    .. math::

        mish(x) = x * tanh(softplus(x)) = x * tanh(ln(1 + e^{x}))

    Shape:
        - Input: Arbitrary. Use the keyword argument `input_shape`
        (tuple of integers, does not include the samples axis)
        when using this layer as the first layer in a model.

        - Output: Same shape as the input.

    Examples:
        from activation_mish import Mish
        x = Mish('Mish', name="mish_name")(x_input)
    """

    def __init__(self, activation, **kwargs):
        super(Mish, self).__init__(activation, **kwargs)
        self.__name__ = 'Mish'


def mish(inputs):
    return inputs * tf.math.tanh(tf.math.softplus(inputs))


get_custom_objects().update({'Mish': Mish(mish)})