class_docstr: Generate data for a Pascal VOC dataset.
  
  See http://host.robots.ox.ac.uk/pascal/VOC/ for more information.
class_docstr_tok: ["Generate","data","for","a","Pascal","VOC","dataset",".","See","http",":","\/\/host.robots.ox.ac.uk\/pascal\/VOC\/","for","more","information","."]
docstr: Number of classes in the dataset.
          
docstr_tok: ["Number","of","classes","in","the","dataset","."]
code: def num_classes(self):
      """Number of classes in the dataset."""
      return len(self.classes)
  
imports: from ..preprocessing.generator import Generator
  from ..utils.image import read_image_bgr
  import os
  import numpy
  from six import raise_from
  from PIL import Image
label_desc: Use image node_id 3 for calling the PascalVocGenerator obj's underlying member method code with example usage: obj.num_classes() and returns: len