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# Copyright 2020 The TensorFlow Authors. All Rights Reserved.
#
# 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.
# ==============================================================================
"""Common utility for object detection tf.train.SequenceExamples."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
import tensorflow.compat.v1 as tf


def context_float_feature(ndarray):
  """Converts a numpy float array to a context float feature.



  Args:

    ndarray: A numpy float array.



  Returns:

    A context float feature.

  """
  feature = tf.train.Feature()
  for val in ndarray:
    if isinstance(val, np.ndarray):
      val = val.item()
    feature.float_list.value.append(val)
  return feature


def context_int64_feature(ndarray):
  """Converts a numpy array to a context int64 feature.



  Args:

    ndarray: A numpy int64 array.



  Returns:

    A context int64 feature.

  """
  feature = tf.train.Feature()
  for val in ndarray:
    if isinstance(val, np.ndarray):
      val = val.item()
    feature.int64_list.value.append(val)
  return feature


def context_bytes_feature(ndarray):
  """Converts a numpy bytes array to a context bytes feature.



  Args:

    ndarray: A numpy bytes array.



  Returns:

    A context bytes feature.

  """
  feature = tf.train.Feature()
  for val in ndarray:
    if isinstance(val, np.ndarray):
      val = val.tolist()
    feature.bytes_list.value.append(tf.compat.as_bytes(val))
  return feature


def sequence_float_feature(ndarray):
  """Converts a numpy float array to a sequence float feature.



  Args:

    ndarray: A numpy float array.



  Returns:

    A sequence float feature.

  """
  feature_list = tf.train.FeatureList()
  for row in ndarray:
    feature = feature_list.feature.add()
    if row.size:
      feature.float_list.value[:] = np.ravel(row)
  return feature_list


def sequence_int64_feature(ndarray):
  """Converts a numpy int64 array to a sequence int64 feature.



  Args:

    ndarray: A numpy int64 array.



  Returns:

    A sequence int64 feature.

  """
  feature_list = tf.train.FeatureList()
  for row in ndarray:
    feature = feature_list.feature.add()
    if row.size:
      feature.int64_list.value[:] = np.ravel(row)
  return feature_list


def sequence_bytes_feature(ndarray):
  """Converts a bytes float array to a sequence bytes feature.



  Args:

    ndarray: A numpy bytes array.



  Returns:

    A sequence bytes feature.

  """
  feature_list = tf.train.FeatureList()
  for row in ndarray:
    if isinstance(row, np.ndarray):
      row = row.tolist()
    feature = feature_list.feature.add()
    if row:
      row = [tf.compat.as_bytes(val) for val in row]
      feature.bytes_list.value[:] = np.ravel(row)
  return feature_list


def sequence_strings_feature(strings):
  new_str_arr = []
  for single_str in strings:
    new_str_arr.append(tf.train.Feature(
        bytes_list=tf.train.BytesList(
            value=[single_str.encode('utf8')])))
  return tf.train.FeatureList(feature=new_str_arr)


def boxes_to_box_components(bboxes):
  """Converts a list of numpy arrays (boxes) to box components.



  Args:

    bboxes: A numpy array of bounding boxes.



  Returns:

    Bounding box component lists.

  """
  ymin_list = []
  xmin_list = []
  ymax_list = []
  xmax_list = []
  for bbox in bboxes:
    if len(bbox) != 0:
      bbox = np.array(bbox).astype(np.float32)
      ymin, xmin, ymax, xmax = np.split(bbox, 4, axis=1)
    else:
      ymin, xmin, ymax, xmax = [], [], [], []
    ymin_list.append(np.reshape(ymin, [-1]))
    xmin_list.append(np.reshape(xmin, [-1]))
    ymax_list.append(np.reshape(ymax, [-1]))
    xmax_list.append(np.reshape(xmax, [-1]))
  return ymin_list, xmin_list, ymax_list, xmax_list


def make_sequence_example(dataset_name,

                          video_id,

                          encoded_images,

                          image_height,

                          image_width,

                          image_format=None,

                          image_source_ids=None,

                          timestamps=None,

                          is_annotated=None,

                          bboxes=None,

                          label_strings=None,

                          detection_bboxes=None,

                          detection_classes=None,

                          detection_scores=None,

                          use_strs_for_source_id=False,

                          context_features=None,

                          context_feature_length=None,

                          context_features_image_id_list=None):
  """Constructs tf.SequenceExamples.



  Args:

    dataset_name: String with dataset name.

    video_id: String with video id.

    encoded_images: A [num_frames] list (or numpy array) of encoded image

      frames.

    image_height: Height of the images.

    image_width: Width of the images.

    image_format: Format of encoded images.

    image_source_ids: (Optional) A [num_frames] list of unique string ids for

      each image.

    timestamps: (Optional) A [num_frames] list (or numpy array) array with image

      timestamps.

    is_annotated: (Optional) A [num_frames] list (or numpy array) array

      in which each element indicates whether the frame has been annotated

      (1) or not (0).

    bboxes: (Optional) A list (with num_frames elements) of [num_boxes_i, 4]

      numpy float32 arrays holding boxes for each frame.

    label_strings: (Optional) A list (with num_frames_elements) of [num_boxes_i]

      numpy string arrays holding object string labels for each frame.

    detection_bboxes: (Optional) A list (with num_frames elements) of

      [num_boxes_i, 4] numpy float32 arrays holding prediction boxes for each

      frame.

    detection_classes: (Optional) A list (with num_frames_elements) of

      [num_boxes_i] numpy int64 arrays holding predicted classes for each frame.

    detection_scores: (Optional) A list (with num_frames_elements) of

      [num_boxes_i] numpy float32 arrays holding predicted object scores for

      each frame.

    use_strs_for_source_id: (Optional) Whether to write the source IDs as

      strings rather than byte lists of characters.

    context_features: (Optional) A list or numpy array of features to use in

      Context R-CNN, of length num_context_features * context_feature_length.

    context_feature_length: (Optional) The length of each context feature, used

      for reshaping.

    context_features_image_id_list: (Optional) A list of image ids of length

      num_context_features corresponding to the context features.



  Returns:

    A tf.train.SequenceExample.

  """
  num_frames = len(encoded_images)
  image_encoded = np.expand_dims(encoded_images, axis=-1)
  if timestamps is None:
    timestamps = np.arange(num_frames)
  image_timestamps = np.expand_dims(timestamps, axis=-1)

  # Context fields.
  context_dict = {
      'example/dataset_name': context_bytes_feature([dataset_name]),
      'clip/start/timestamp': context_int64_feature([image_timestamps[0][0]]),
      'clip/end/timestamp': context_int64_feature([image_timestamps[-1][0]]),
      'clip/frames': context_int64_feature([num_frames]),
      'image/channels': context_int64_feature([3]),
      'image/height': context_int64_feature([image_height]),
      'image/width': context_int64_feature([image_width]),
      'clip/media_id': context_bytes_feature([video_id])
  }

  # Sequence fields.
  feature_list = {
      'image/encoded': sequence_bytes_feature(image_encoded),
      'image/timestamp': sequence_int64_feature(image_timestamps),
  }

  # Add optional fields.
  if image_format is not None:
    context_dict['image/format'] = context_bytes_feature([image_format])
  if image_source_ids is not None:
    if use_strs_for_source_id:
      feature_list['image/source_id'] = sequence_strings_feature(
          image_source_ids)
    else:
      feature_list['image/source_id'] = sequence_bytes_feature(image_source_ids)
  if bboxes is not None:
    bbox_ymin, bbox_xmin, bbox_ymax, bbox_xmax = boxes_to_box_components(bboxes)
    feature_list['region/bbox/xmin'] = sequence_float_feature(bbox_xmin)
    feature_list['region/bbox/xmax'] = sequence_float_feature(bbox_xmax)
    feature_list['region/bbox/ymin'] = sequence_float_feature(bbox_ymin)
    feature_list['region/bbox/ymax'] = sequence_float_feature(bbox_ymax)
    if is_annotated is None:
      is_annotated = np.ones(num_frames, dtype=np.int64)
    is_annotated = np.expand_dims(is_annotated, axis=-1)
    feature_list['region/is_annotated'] = sequence_int64_feature(is_annotated)

  if label_strings is not None:
    feature_list['region/label/string'] = sequence_bytes_feature(
        label_strings)

  if detection_bboxes is not None:
    det_bbox_ymin, det_bbox_xmin, det_bbox_ymax, det_bbox_xmax = (
        boxes_to_box_components(detection_bboxes))
    feature_list['predicted/region/bbox/xmin'] = sequence_float_feature(
        det_bbox_xmin)
    feature_list['predicted/region/bbox/xmax'] = sequence_float_feature(
        det_bbox_xmax)
    feature_list['predicted/region/bbox/ymin'] = sequence_float_feature(
        det_bbox_ymin)
    feature_list['predicted/region/bbox/ymax'] = sequence_float_feature(
        det_bbox_ymax)
  if detection_classes is not None:
    feature_list['predicted/region/label/index'] = sequence_int64_feature(
        detection_classes)
  if detection_scores is not None:
    feature_list['predicted/region/label/confidence'] = sequence_float_feature(
        detection_scores)

  if context_features is not None:
    context_dict['image/context_features'] = context_float_feature(
        context_features)
  if context_feature_length is not None:
    context_dict['image/context_feature_length'] = context_int64_feature(
        context_feature_length)
  if context_features_image_id_list is not None:
    context_dict['image/context_features_image_id_list'] = (
        context_bytes_feature(context_features_image_id_list))

  context = tf.train.Features(feature=context_dict)
  feature_lists = tf.train.FeatureLists(feature_list=feature_list)

  sequence_example = tf.train.SequenceExample(
      context=context,
      feature_lists=feature_lists)
  return sequence_example