class_docstr: This generate anchors.
  
  Parameters
  ----------
  stride : int
      Anchor stride
  ratios : tuple
      Anchor ratios
  scales : tuple
      Anchor scales
  size : int
      anchor size
class_docstr_tok: ["This","generate","anchors",".","Parameters","--","--","--","--","--","stride",":","int","Anchor","stride","ratios",":","tuple","Anchor","ratios","scales",":","tuple","Anchor","scales","size",":","int","anchor","size"]
code: def __init__(self, stride, ratios, scales, image_center=0, size=0):
      self.stride = stride
      self.ratios = ratios
      self.scales = scales
      self.image_center = image_center
      self.size = size
      self.anchor_num = len(self.scales) * len(self.ratios)
      self.anchors = None
      self.generate_anchors()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import math
  from collections import namedtuple
  import numpy
  import mxnet
  from mxnet import nd
  from gluoncv.utils.filesystem import try_import_cv2
label_desc: Use image node_id 1 to create a new Anchors object  with example: obj = Anchors(stride, ratios, scales, image_center, size)