class_docstr: Multibox head of Single Shot Multibox Detector.
  
  This is a head part of Single Shot Multibox Detector [#]_.
  This link computes :obj:`mb_locs` and :obj:`mb_confs` from feature maps.
  :obj:`mb_locs` contains information of the coordinates of bounding boxes
  and :obj:`mb_confs` contains confidence scores of each classes.
  
  .. [#] Wei Liu, Dragomir Anguelov, Dumitru Erhan,
     Christian Szegedy, Scott Reed, Cheng-Yang Fu, Alexander C. Berg.
     SSD: Single Shot MultiBox Detector. ECCV 2016.
  
  Args:
      n_class (int): The number of classes possibly including the background.
      aspect_ratios (iterable of tuple or int): The aspect ratios of
          default bounding boxes for each feature map.
      initialW: An initializer used in
          :meth:`chainer.links.Convolution2d.__init__`.
          The default value is :class:`chainer.initializers.LeCunUniform`.
      initial_bias: An initializer used in
          :meth:`chainer.links.Convolution2d.__init__`.
          The default value is :class:`chainer.initializers.Zero`.
code: def __init__(
      self, n_class, aspect_ratios, initialW=None, initial_bias=None
  ):
      self.n_class = n_class
      self.aspect_ratios = aspect_ratios
  
      super(Multibox, self).__init__()
      with self.init_scope():
          self.loc = chainer.ChainList()
          self.conf = chainer.ChainList()
  
      if initialW is None:
          initialW = initializers.LeCunUniform()
      if initial_bias is None:
          initial_bias = initializers.Zero()
      init = {"initialW": initialW, "initial_bias": initial_bias}
  
      for ar in aspect_ratios:
          n = (len(ar) + 1) * 2
          self.loc.add_link(L.Convolution2D(n * 4, 3, pad=1, **init))
          self.conf.add_link(
              L.Convolution2D(n * self.n_class, 3, pad=1, **init)
          )
  
file_path: chainercv/chainercv/links/model/ssd/multibox.py
imports: import chainer
  import chainer.functions
  from chainer import initializers
  import chainer.links
label_desc: Use image node_id 1 to create a new Multibox object from inherited base classes: chainer with example: obj = Multibox(n_class, aspect_ratios, initialW, initial_bias)