# Source code for rl_coach.filters.observation.observation_squeeze_filter

    #
    # Copyright (c) 2017 Intel Corporation
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    #      http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    # See the License for the specific language governing permissions and
    # limitations under the License.
    #

    import numpy as np

    from rl_coach.core_types import ObservationType
    from rl_coach.filters.observation.observation_filter import ObservationFilter
    from rl_coach.spaces import ObservationSpace

    class ObservationSqueezeFilter(ObservationFilter):
        """
        Removes redundant axes from the observation, which are axes with a dimension of 1.
        """
        def __init__(self, axis: int = None):
            """
            :param axis: Specifies which axis to remove. If set to None, all the axes of size 1 will be removed.
            """
            super().__init__()
            self.axis = axis

        def validate_input_observation_space(self, input_observation_space: ObservationSpace):
            if self.axis is None:
                return

            shape = input_observation_space.shape
            if self.axis >= len(shape) or self.axis < -len(shape):
                raise ValueError("The given axis does not exist in the context of the input observation shape. ")

        def filter(self, observation: ObservationType, update_internal_state: bool=True) -> ObservationType:
            return observation.squeeze(axis=self.axis)

        def get_filtered_observation_space(self, input_observation_space: ObservationSpace) -> ObservationSpace:
            dummy_tensor = np.random.rand(*tuple(input_observation_space.shape))
            input_observation_space.shape = dummy_tensor.squeeze(axis=self.axis).shape
            return input_observation_space