content: __author__ = 'tylin'
  __version__ = '1.0.1'
  # Interface for accessing the Microsoft COCO dataset.
  
  # Microsoft COCO is a large image dataset designed for object detection,
  # segmentation, and caption generation. pycocotools is a Python API that
  # assists in loading, parsing and visualizing the annotations in COCO.
  # Please visit http://mscoco.org/ for more information on COCO, including
  # for the data, paper, and tutorials. The exact format of the annotations
  # is also described on the COCO website. For example usage of the pycocotools
  # please see pycocotools_demo.ipynb. In addition to this API, please download both
  # the COCO images and annotations in order to run the demo.
  
  # An alternative to using the API is to load the annotations directly
  # into Python dictionary
  # Using the API provides additional utility functions. Note that this API
  # supports both *instance* and *caption* annotations. In the case of
  # captions not all functions are defined (e.g. categories are undefined).
  
  # The following API functions are defined:
  #  COCO       - COCO api class that loads COCO annotation file and prepare data structures.
  #  decodeMask - Decode binary mask M encoded via run-length encoding.
  #  encodeMask - Encode binary mask M using run-length encoding.
  #  getAnnIds  - Get ann ids that satisfy given filter conditions.
  #  getCatIds  - Get cat ids that satisfy given filter conditions.
  #  getImgIds  - Get img ids that satisfy given filter conditions.
  #  loadAnns   - Load anns with the specified ids.
  #  loadCats   - Load cats with the specified ids.
  #  loadImgs   - Load imgs with the specified ids.
  #  segToMask  - Convert polygon segmentation to binary mask.
  #  showAnns   - Display the specified annotations.
  #  loadRes    - Load algorithm results and create API for accessing them.
  #  download   - Download COCO images from mscoco.org server.
  # Throughout the API "ann"=annotation, "cat"=category, and "img"=image.
  # Help on each functions can be accessed by: "help COCO>function".
  
  # See also COCO>decodeMask,
  # COCO>encodeMask, COCO>getAnnIds, COCO>getCatIds,
  # COCO>getImgIds, COCO>loadAnns, COCO>loadCats,
  # COCO>loadImgs, COCO>segToMask, COCO>showAnns
  
  # Microsoft COCO Toolbox.      version 2.0
  # Data, paper, and tutorials available at:  http://mscoco.org/
  # Code written by Piotr Dollar and Tsung-Yi Lin, 2014.
  # Licensed under the Simplified BSD License [see bsd.txt]
  
  import json
  import datetime
  import time
  # import matplotlib.pyplot as plt
  # from matplotlib.collections import PatchCollection
  # from matplotlib.patches import Polygon
  import numpy as np
  # from skimage.draw import polygon
  import urllib
  import copy
  import itertools
  import mask
  import os
  
  class COCO:
      def __init__(self, annotation_file=None):
          """
          Constructor of Microsoft COCO helper class for reading and visualizing annotations.
          :param annotation_file (str): location of annotation file
          :param image_folder (str): location to the folder that hosts images.
          :return:
          """
          # load dataset
          self.dataset = {}
          self.anns = []
          self.imgToAnns = {}
          self.catToImgs = {}
          self.imgs = {}
          self.cats = {}
          if not annotation_file == None:
              print 'loading annotations into memory...'
              tic = time.time()
              dataset = json.load(open(annotation_file, 'r'))
              print 'Done (t=%0.2fs)'%(time.time()- tic)
              self.dataset = dataset
              self.createIndex()
  
      def createIndex(self):
          # create index
          print 'creating index...'
          anns = {}
          imgToAnns = {}
          catToImgs = {}
          cats = {}
          imgs = {}
          if 'annotations' in self.dataset:
              imgToAnns = {ann['image_id']: [] for ann in self.dataset['annotations']}
              anns =      {ann['id']:       [] for ann in self.dataset['annotations']}
              for ann in self.dataset['annotations']:
                  imgToAnns[ann['image_id']] += [ann]
                  anns[ann['id']] = ann
  
          if 'images' in self.dataset:
              imgs      = {im['id']: {} for im in self.dataset['images']}
              for img in self.dataset['images']:
                  imgs[img['id']] = img
  
          if 'categories' in self.dataset:
              cats = {cat['id']: [] for cat in self.dataset['categories']}
              for cat in self.dataset['categories']:
                  cats[cat['id']] = cat
              catToImgs = {cat['id']: [] for cat in self.dataset['categories']}
              if 'annotations' in self.dataset:
                  for ann in self.dataset['annotations']:
                      catToImgs[ann['category_id']] += [ann['image_id']]
  
          print 'index created!'
  
          # create class members
          self.anns = anns
          self.imgToAnns = imgToAnns
          self.catToImgs = catToImgs
          self.imgs = imgs
          self.cats = cats
  
      def info(self):
          """
          Print information about the annotation file.
          :return:
          """
          for key, value in self.dataset['info'].items():
              print '%s: %s'%(key, value)
  
      def getAnnIds(self, imgIds=[], catIds=[], areaRng=[], iscrowd=None):
          """
          Get ann ids that satisfy given filter conditions. default skips that filter
          :param imgIds  (int array)     : get anns for given imgs
                 catIds  (int array)     : get anns for given cats
                 areaRng (float array)   : get anns for given area range (e.g. [0 inf])
                 iscrowd (boolean)       : get anns for given crowd label (False or True)
          :return: ids (int array)       : integer array of ann ids
          """
          imgIds = imgIds if type(imgIds) == list else [imgIds]
          catIds = catIds if type(catIds) == list else [catIds]
  
          if len(imgIds) == len(catIds) == len(areaRng) == 0:
              anns = self.dataset['annotations']
          else:
              if not len(imgIds) == 0:
                  # this can be changed by defaultdict
                  lists = [self.imgToAnns[imgId] for imgId in imgIds if imgId in self.imgToAnns]
                  anns = list(itertools.chain.from_iterable(lists))
              else:
                  anns = self.dataset['annotations']
              anns = anns if len(catIds)  == 0 else [ann for ann in anns if ann['category_id'] in catIds]
              anns = anns if len(areaRng) == 0 else [ann for ann in anns if ann['area'] > areaRng[0] and ann['area'] < areaRng[1]]
          if not iscrowd == None:
              ids = [ann['id'] for ann in anns if ann['iscrowd'] == iscrowd]
          else:
              ids = [ann['id'] for ann in anns]
          return ids
  
      def getCatIds(self, catNms=[], supNms=[], catIds=[]):
          """
          filtering parameters. default skips that filter.
          :param catNms (str array)  : get cats for given cat names
          :param supNms (str array)  : get cats for given supercategory names
          :param catIds (int array)  : get cats for given cat ids
          :return: ids (int array)   : integer array of cat ids
          """
          catNms = catNms if type(catNms) == list else [catNms]
          supNms = supNms if type(supNms) == list else [supNms]
          catIds = catIds if type(catIds) == list else [catIds]
  
          if len(catNms) == len(supNms) == len(catIds) == 0:
              cats = self.dataset['categories']
          else:
              cats = self.dataset['categories']
              cats = cats if len(catNms) == 0 else [cat for cat in cats if cat['name']          in catNms]
              cats = cats if len(supNms) == 0 else [cat for cat in cats if cat['supercategory'] in supNms]
              cats = cats if len(catIds) == 0 else [cat for cat in cats if cat['id']            in catIds]
          ids = [cat['id'] for cat in cats]
          return ids
  
      def getImgIds(self, imgIds=[], catIds=[]):
          '''
          Get img ids that satisfy given filter conditions.
          :param imgIds (int array) : get imgs for given ids
          :param catIds (int array) : get imgs with all given cats
          :return: ids (int array)  : integer array of img ids
          '''
          imgIds = imgIds if type(imgIds) == list else [imgIds]
          catIds = catIds if type(catIds) == list else [catIds]
  
          if len(imgIds) == len(catIds) == 0:
              ids = self.imgs.keys()
          else:
              ids = set(imgIds)
              for i, catId in enumerate(catIds):
                  if i == 0 and len(ids) == 0:
                      ids = set(self.catToImgs[catId])
                  else:
                      ids &= set(self.catToImgs[catId])
          return list(ids)
  
      def loadAnns(self, ids=[]):
          """
          Load anns with the specified ids.
          :param ids (int array)       : integer ids specifying anns
          :return: anns (object array) : loaded ann objects
          """
          if type(ids) == list:
              return [self.anns[id] for id in ids]
          elif type(ids) == int:
              return [self.anns[ids]]
  
      def loadCats(self, ids=[]):
          """
          Load cats with the specified ids.
          :param ids (int array)       : integer ids specifying cats
          :return: cats (object array) : loaded cat objects
          """
          if type(ids) == list:
              return [self.cats[id] for id in ids]
          elif type(ids) == int:
              return [self.cats[ids]]
  
      def loadImgs(self, ids=[]):
          """
          Load anns with the specified ids.
          :param ids (int array)       : integer ids specifying img
          :return: imgs (object array) : loaded img objects
          """
          if type(ids) == list:
              return [self.imgs[id] for id in ids]
          elif type(ids) == int:
              return [self.imgs[ids]]
  
      def showAnns(self, anns):
          """
          Display the specified annotations.
          :param anns (array of object): annotations to display
          :return: None
          """
          if len(anns) == 0:
              return 0
          if 'segmentation' in anns[0]:
              datasetType = 'instances'
          elif 'caption' in anns[0]:
              datasetType = 'captions'
          if datasetType == 'instances':
              ax = plt.gca()
              polygons = []
              color = []
              for ann in anns:
                  c = np.random.random((1, 3)).tolist()[0]
                  if type(ann['segmentation']) == list:
                      # polygon
                      for seg in ann['segmentation']:
                          poly = np.array(seg).reshape((len(seg)/2, 2))
                          polygons.append(Polygon(poly, True,alpha=0.4))
                          color.append(c)
                  else:
                      # mask
                      t = self.imgs[ann['image_id']]
                      if type(ann['segmentation']['counts']) == list:
                          rle = mask.frPyObjects([ann['segmentation']], t['height'], t['width'])
                      else:
                          rle = [ann['segmentation']]
                      m = mask.decode(rle)
                      img = np.ones( (m.shape[0], m.shape[1], 3) )
                      if ann['iscrowd'] == 1:
                          color_mask = np.array([2.0,166.0,101.0])/255
                      if ann['iscrowd'] == 0:
                          color_mask = np.random.random((1, 3)).tolist()[0]
                      for i in range(3):
                          img[:,:,i] = color_mask[i]
                      ax.imshow(np.dstack( (img, m*0.5) ))
              p = PatchCollection(polygons, facecolors=color, edgecolors=(0,0,0,1), linewidths=3, alpha=0.4)
              ax.add_collection(p)
          elif datasetType == 'captions':
              for ann in anns:
                  print ann['caption']
  
      def loadRes(self, resFile):
          """
          Load result file and return a result api object.
          :param   resFile (str)     : file name of result file
          :return: res (obj)         : result api object
          """
          res = COCO()
          res.dataset['images'] = [img for img in self.dataset['images']]
          # res.dataset['info'] = copy.deepcopy(self.dataset['info'])
          # res.dataset['licenses'] = copy.deepcopy(self.dataset['licenses'])
  
          print 'Loading and preparing results...     '
          tic = time.time()
          anns    = json.load(open(resFile))
          assert type(anns) == list, 'results in not an array of objects'
          annsImgIds = [ann['image_id'] for ann in anns]
          assert set(annsImgIds) == (set(annsImgIds) & set(self.getImgIds())), \
                 'Results do not correspond to current coco set'
          if 'caption' in anns[0]:
              imgIds = set([img['id'] for img in res.dataset['images']]) & set([ann['image_id'] for ann in anns])
              res.dataset['images'] = [img for img in res.dataset['images'] if img['id'] in imgIds]
              for id, ann in enumerate(anns):
                  ann['id'] = id+1
          elif 'bbox' in anns[0] and not anns[0]['bbox'] == []:
              res.dataset['categories'] = copy.deepcopy(self.dataset['categories'])
              for id, ann in enumerate(anns):
                  bb = ann['bbox']
                  x1, x2, y1, y2 = [bb[0], bb[0]+bb[2], bb[1], bb[1]+bb[3]]
                  if not 'segmentation' in ann:
                      ann['segmentation'] = [[x1, y1, x1, y2, x2, y2, x2, y1]]
                  ann['area'] = bb[2]*bb[3]
                  ann['id'] = id+1
                  ann['iscrowd'] = 0
          elif 'segmentation' in anns[0]:
              res.dataset['categories'] = copy.deepcopy(self.dataset['categories'])
              for id, ann in enumerate(anns):
                  # now only support compressed RLE format as segmentation results
                  ann['area'] = mask.area([ann['segmentation']])[0]
                  if not 'bbox' in ann:
                      ann['bbox'] = mask.toBbox([ann['segmentation']])[0]
                  ann['id'] = id+1
                  ann['iscrowd'] = 0
          print 'DONE (t=%0.2fs)'%(time.time()- tic)
  
          res.dataset['annotations'] = anns
          res.createIndex()
          return res
  
      def download( self, tarDir = None, imgIds = [] ):
          '''
          Download COCO images from mscoco.org server.
          :param tarDir (str): COCO results directory name
                 imgIds (list): images to be downloaded
          :return:
          '''
          if tarDir is None:
              print 'Please specify target directory'
              return -1
          if len(imgIds) == 0:
              imgs = self.imgs.values()
          else:
              imgs = self.loadImgs(imgIds)
          N = len(imgs)
          if not os.path.exists(tarDir):
              os.makedirs(tarDir)
          for i, img in enumerate(imgs):
              tic = time.time()
              fname = os.path.join(tarDir, img['file_name'])
              if not os.path.exists(fname):
                  urllib.urlretrieve(img['coco_url'], fname)
              print 'downloaded %d/%d images (t=%.1fs)'%(i, N, time.time()- tic)
  