text: #! /usr/bin/env python
  # coding=utf-8
  
  import os
  import cv2
  import random
  import numpy as np
  import tensorflow as tf
  import core.utils as utils
  from core.config import cfg
  
  
  class Dataset(object):
      """implement Dataset here"""
  
      def __init__(self, FLAGS, is_training: bool, dataset_type: str = "converted_coco"):
          self.tiny = FLAGS.tiny
          self.strides, self.anchors, NUM_CLASS, XYSCALE = utils.load_config(FLAGS)
          self.dataset_type = dataset_type
  
          self.annot_path = (
              cfg.TRAIN.ANNOT_PATH if is_training else cfg.TEST.ANNOT_PATH
          )
          self.input_sizes = (
              cfg.TRAIN.INPUT_SIZE if is_training else cfg.TEST.INPUT_SIZE
          )
          self.batch_size = (
              cfg.TRAIN.BATCH_SIZE if is_training else cfg.TEST.BATCH_SIZE
          )
          self.data_aug = cfg.TRAIN.DATA_AUG if is_training else cfg.TEST.DATA_AUG
  
          self.train_input_sizes = cfg.TRAIN.INPUT_SIZE
          self.classes = utils.read_class_names(cfg.YOLO.CLASSES)
          self.num_classes = len(self.classes)
          self.anchor_per_scale = cfg.YOLO.ANCHOR_PER_SCALE
          self.max_bbox_per_scale = 150
  
          self.annotations = self.load_annotations()
          self.num_samples = len(self.annotations)
          self.num_batchs = int(np.ceil(self.num_samples / self.batch_size))
          self.batch_count = 0
  
      def load_annotations(self):
          with open(self.annot_path, "r") as f:
              txt = f.readlines()
              if self.dataset_type == "converted_coco":
                  annotations = [
                      line.strip()
                      for line in txt
                      if len(line.strip().split()[1:]) != 0
                  ]
              elif self.dataset_type == "yolo":
                  annotations = []
                  for line in txt:
                      image_path = line.strip()
                      root, _ = os.path.splitext(image_path)
                      with open(root + ".txt") as fd:
                          boxes = fd.readlines()
                          string = ""
                          for box in boxes:
                              box = box.strip()
                              box = box.split()
                              class_num = int(box[0])
                              center_x = float(box[1])
                              center_y = float(box[2])
                              half_width = float(box[3]) / 2
                              half_height = float(box[4]) / 2
                              string += " {},{},{},{},{}".format(
                                  center_x - half_width,
                                  center_y - half_height,
                                  center_x + half_width,
                                  center_y + half_height,
                                  class_num,
                              )
                          annotations.append(image_path + string)
  
          np.random.shuffle(annotations)
          return annotations
  
      def __iter__(self):
          return self
  
      def __next__(self):
          with tf.device("/cpu:0"):
              # self.train_input_size = random.choice(self.train_input_sizes)
              self.train_input_size = cfg.TRAIN.INPUT_SIZE
              self.train_output_sizes = self.train_input_size // self.strides
  
              batch_image = np.zeros(
                  (
                      self.batch_size,
                      self.train_input_size,
                      self.train_input_size,
                      3,
                  ),
                  dtype=np.float32,
              )
  
              batch_label_sbbox = np.zeros(
                  (
                      self.batch_size,
                      self.train_output_sizes[0],
                      self.train_output_sizes[0],
                      self.anchor_per_scale,
                      5 + self.num_classes,
                  ),
                  dtype=np.float32,
              )
              batch_label_mbbox = np.zeros(
                  (
                      self.batch_size,
                      self.train_output_sizes[1],
                      self.train_output_sizes[1],
                      self.anchor_per_scale,
                      5 + self.num_classes,
                  ),
                  dtype=np.float32,
              )
              batch_label_lbbox = np.zeros(
                  (
                      self.batch_size,
                      self.train_output_sizes[2],
                      self.train_output_sizes[2],
                      self.anchor_per_scale,
                      5 + self.num_classes,
                  ),
                  dtype=np.float32,
              )
  
              batch_sbboxes = np.zeros(
                  (self.batch_size, self.max_bbox_per_scale, 4), dtype=np.float32
              )
              batch_mbboxes = np.zeros(
                  (self.batch_size, self.max_bbox_per_scale, 4), dtype=np.float32
              )
              batch_lbboxes = np.zeros(
                  (self.batch_size, self.max_bbox_per_scale, 4), dtype=np.float32
              )
  
              num = 0
              if self.batch_count < self.num_batchs:
                  while num < self.batch_size:
                      index = self.batch_count * self.batch_size + num
                      if index >= self.num_samples:
                          index -= self.num_samples
                      annotation = self.annotations[index]
                      image, bboxes = self.parse_annotation(annotation)
                      (
                          label_sbbox,
                          label_mbbox,
                          label_lbbox,
                          sbboxes,
                          mbboxes,
                          lbboxes,
                      ) = self.preprocess_true_boxes(bboxes)
  
                      batch_image[num, :, :, :] = image
                      batch_label_sbbox[num, :, :, :, :] = label_sbbox
                      batch_label_mbbox[num, :, :, :, :] = label_mbbox
                      batch_label_lbbox[num, :, :, :, :] = label_lbbox
                      batch_sbboxes[num, :, :] = sbboxes
                      batch_mbboxes[num, :, :] = mbboxes
                      batch_lbboxes[num, :, :] = lbboxes
                      num += 1
                  self.batch_count += 1
                  batch_smaller_target = batch_label_sbbox, batch_sbboxes
                  batch_medium_target = batch_label_mbbox, batch_mbboxes
                  batch_larger_target = batch_label_lbbox, batch_lbboxes
  
                  return (
                      batch_image,
                      (
                          batch_smaller_target,
                          batch_medium_target,
                          batch_larger_target,
                      ),
                  )
              else:
                  self.batch_count = 0
                  np.random.shuffle(self.annotations)
                  raise StopIteration
  
      def random_horizontal_flip(self, image, bboxes):
          if random.random() < 0.5:
              _, w, _ = image.shape
              image = image[:, ::-1, :]
              bboxes[:, [0, 2]] = w - bboxes[:, [2, 0]]
  
          return image, bboxes
  
      def random_crop(self, image, bboxes):
          if random.random() < 0.5:
              h, w, _ = image.shape
              max_bbox = np.concatenate(
                  [
                      np.min(bboxes[:, 0:2], axis=0),
                      np.max(bboxes[:, 2:4], axis=0),
                  ],
                  axis=-1,
              )
  
              max_l_trans = max_bbox[0]
              max_u_trans = max_bbox[1]
              max_r_trans = w - max_bbox[2]
              max_d_trans = h - max_bbox[3]
  
              crop_xmin = max(
                  0, int(max_bbox[0] - random.uniform(0, max_l_trans))
              )
              crop_ymin = max(
                  0, int(max_bbox[1] - random.uniform(0, max_u_trans))
              )
              crop_xmax = max(
                  w, int(max_bbox[2] + random.uniform(0, max_r_trans))
              )
              crop_ymax = max(
                  h, int(max_bbox[3] + random.uniform(0, max_d_trans))
              )
  
              image = image[crop_ymin:crop_ymax, crop_xmin:crop_xmax]
  
              bboxes[:, [0, 2]] = bboxes[:, [0, 2]] - crop_xmin
              bboxes[:, [1, 3]] = bboxes[:, [1, 3]] - crop_ymin
  
          return image, bboxes
  
      def random_translate(self, image, bboxes):
          if random.random() < 0.5:
              h, w, _ = image.shape
              max_bbox = np.concatenate(
                  [
                      np.min(bboxes[:, 0:2], axis=0),
                      np.max(bboxes[:, 2:4], axis=0),
                  ],
                  axis=-1,
              )
  
              max_l_trans = max_bbox[0]
              max_u_trans = max_bbox[1]
              max_r_trans = w - max_bbox[2]
              max_d_trans = h - max_bbox[3]
  
              tx = random.uniform(-(max_l_trans - 1), (max_r_trans - 1))
              ty = random.uniform(-(max_u_trans - 1), (max_d_trans - 1))
  
              M = np.array([[1, 0, tx], [0, 1, ty]])
              image = cv2.warpAffine(image, M, (w, h))
  
              bboxes[:, [0, 2]] = bboxes[:, [0, 2]] + tx
              bboxes[:, [1, 3]] = bboxes[:, [1, 3]] + ty
  
          return image, bboxes
  
      def parse_annotation(self, annotation):
          line = annotation.split()
          image_path = line[0]
          if not os.path.exists(image_path):
              raise KeyError("%s does not exist ... " % image_path)
          image = cv2.imread(image_path)
          if self.dataset_type == "converted_coco":
              bboxes = np.array(
                  [list(map(int, box.split(","))) for box in line[1:]]
              )
          elif self.dataset_type == "yolo":
              height, width, _ = image.shape
              bboxes = np.array(
                  [list(map(float, box.split(","))) for box in line[1:]]
              )
              bboxes = bboxes * np.array([width, height, width, height, 1])
              bboxes = bboxes.astype(np.int64)
  
          if self.data_aug:
              image, bboxes = self.random_horizontal_flip(
                  np.copy(image), np.copy(bboxes)
              )
              image, bboxes = self.random_crop(np.copy(image), np.copy(bboxes))
              image, bboxes = self.random_translate(
                  np.copy(image), np.copy(bboxes)
              )
  
          image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
          image, bboxes = utils.image_preprocess(
              np.copy(image),
              [self.train_input_size, self.train_input_size],
              np.copy(bboxes),
          )
          return image, bboxes
  
  
      def preprocess_true_boxes(self, bboxes):
          label = [
              np.zeros(
                  (
                      self.train_output_sizes[i],
                      self.train_output_sizes[i],
                      self.anchor_per_scale,
                      5 + self.num_classes,
                  )
              )
              for i in range(3)
          ]
          bboxes_xywh = [np.zeros((self.max_bbox_per_scale, 4)) for _ in range(3)]
          bbox_count = np.zeros((3,))
  
          for bbox in bboxes:
              bbox_coor = bbox[:4]
              bbox_class_ind = bbox[4]
  
              onehot = np.zeros(self.num_classes, dtype=np.float)
              onehot[bbox_class_ind] = 1.0
              uniform_distribution = np.full(
                  self.num_classes, 1.0 / self.num_classes
              )
              deta = 0.01
              smooth_onehot = onehot * (1 - deta) + deta * uniform_distribution
  
              bbox_xywh = np.concatenate(
                  [
                      (bbox_coor[2:] + bbox_coor[:2]) * 0.5,
                      bbox_coor[2:] - bbox_coor[:2],
                  ],
                  axis=-1,
              )
              bbox_xywh_scaled = (
                  1.0 * bbox_xywh[np.newaxis, :] / self.strides[:, np.newaxis]
              )
  
              iou = []
              exist_positive = False
              for i in range(3):
                  anchors_xywh = np.zeros((self.anchor_per_scale, 4))
                  anchors_xywh[:, 0:2] = (
                      np.floor(bbox_xywh_scaled[i, 0:2]).astype(np.int32) + 0.5
                  )
                  anchors_xywh[:, 2:4] = self.anchors[i]
  
                  iou_scale = utils.bbox_iou(
                      bbox_xywh_scaled[i][np.newaxis, :], anchors_xywh
                  )
                  iou.append(iou_scale)
                  iou_mask = iou_scale > 0.3
  
                  if np.any(iou_mask):
                      xind, yind = np.floor(bbox_xywh_scaled[i, 0:2]).astype(
                          np.int32
                      )
  
                      label[i][yind, xind, iou_mask, :] = 0
                      label[i][yind, xind, iou_mask, 0:4] = bbox_xywh
                      label[i][yind, xind, iou_mask, 4:5] = 1.0
                      label[i][yind, xind, iou_mask, 5:] = smooth_onehot
  
                      bbox_ind = int(bbox_count[i] % self.max_bbox_per_scale)
                      bboxes_xywh[i][bbox_ind, :4] = bbox_xywh
                      bbox_count[i] += 1
  
                      exist_positive = True
  
              if not exist_positive:
                  best_anchor_ind = np.argmax(np.array(iou).reshape(-1), axis=-1)
                  best_detect = int(best_anchor_ind / self.anchor_per_scale)
                  best_anchor = int(best_anchor_ind % self.anchor_per_scale)
                  xind, yind = np.floor(
                      bbox_xywh_scaled[best_detect, 0:2]
                  ).astype(np.int32)
  
                  label[best_detect][yind, xind, best_anchor, :] = 0
                  label[best_detect][yind, xind, best_anchor, 0:4] = bbox_xywh
                  label[best_detect][yind, xind, best_anchor, 4:5] = 1.0
                  label[best_detect][yind, xind, best_anchor, 5:] = smooth_onehot
  
                  bbox_ind = int(
                      bbox_count[best_detect] % self.max_bbox_per_scale
                  )
                  bboxes_xywh[best_detect][bbox_ind, :4] = bbox_xywh
                  bbox_count[best_detect] += 1
          label_sbbox, label_mbbox, label_lbbox = label
          sbboxes, mbboxes, lbboxes = bboxes_xywh
          return label_sbbox, label_mbbox, label_lbbox, sbboxes, mbboxes, lbboxes
  
      def __len__(self):
          return self.num_batchs
  