import json def main(): xpath = 'caption_all.json' with open(xpath, 'r') as cfile: cap_data = json.load(cfile) print ('There are {:} images'.format( len(cap_data) )) IDs = set() for idx, data in enumerate( cap_data ): IDs.add( data['id'] ) assert len( data['captions'] ) > 0, 'invalid {:}-th caption length : {:} {:}'.format(idx, data['captions'], len(data['captions'])) print ('IDs :: min={:}, max={:}, num={:}'.format(min(IDs), max(IDs), len(IDs))) if __name__ == '__main__': main()