class_docstr: Base dataset for detection.
  
  Args:
      proposal_file (str, optional): Proposals file path. Defaults to None.
      file_client_args (dict): Arguments to instantiate the
          corresponding backend in mmdet <= 3.0.0rc6. Defaults to None.
      backend_args (dict, optional): Arguments to instantiate the
          corresponding backend. Defaults to None.
      return_classes (bool): Whether to return class information
          for open vocabulary-based algorithms. Defaults to False.
      caption_prompt (dict, optional): Prompt for captioning.
          Defaults to None.
class_docstr_tok: ["Base","dataset","for","detection",".","Args",":","proposal_file","(","str",",","optional",")",":","Proposals","file","path",".","Defaults","to","None",".","file_client_args","(","dict",")",":","Arguments","to","instantiate","the","corresponding","backend","in","mmdet","<","=","3.0.0rc6",".","Defaults","to","None",".","backend_args","(","dict",",","optional",")",":","Arguments","to","instantiate","the","corresponding","backend",".","Defaults","to","None",".","return_classes","(","bool",")",":","Whether","to","return","class","information","for","open","vocabulary-based","algorithms",".","Defaults","to","False",".","caption_prompt","(","dict",",","optional",")",":","Prompt","for","captioning",".","Defaults","to","None","."]
docstr: Get COCO category ids by index.
  
  Args:
      idx (int): Index of data.
  
  Returns:
      List[int]: All categories in the image of specified index.
docstr_tok: ["Get","COCO","category","ids","by","index",".","Args",":","idx","(","int",")",":","Index","of","data",".","Returns",":","List","[","int","]",":","All","categories","in","the","image","of","specified","index","."]
code: def get_cat_ids(self, idx: int) -> List[int]:
      """Get COCO category ids by index.
  
      Args:
          idx (int): Index of data.
  
      Returns:
          List[int]: All categories in the image of specified index.
      """
      instances = self.get_data_info(idx)["instances"]
      return [instance["bbox_label"] for instance in instances]
  
file_path: mmdetection/mmdet/datasets/base_det_dataset.py
imports: import os.path
  from typing import List, Optional
  from mmengine.dataset import BaseDataset
  from mmengine.fileio import load
  from mmengine.utils import is_abs
  from ..registry import DATASETS
label_desc: Use image node_id 4 for calling the BaseDetDataset obj's underlying member method code with example usage: obj.get_cat_ids(idx) and returns: unknown