class_docstr: Labelled arrow for use as a quiver plot scale key.
class_docstr_tok: ["Labelled","arrow","for","use","as","a","quiver","plot","scale","key","."]
code: def _init(self):
      if True:  # self._dpi_at_last_init != self.axes.figure.dpi
          if self.Q._dpi_at_last_init != self.Q.axes.figure.dpi:
              self.Q._init()
          self._set_transform()
          with cbook._setattr_cm(
              self.Q,
              pivot=self.pivot[self.labelpos],
              # Hack: save and restore the Umask
              Umask=ma.nomask,
          ):
              u = self.U * np.cos(np.radians(self.angle))
              v = self.U * np.sin(np.radians(self.angle))
              angle = (
                  self.Q.angles
                  if isinstance(self.Q.angles, str)
                  else "uv"
              )
              self.verts = self.Q._make_verts(
                  np.array([u]), np.array([v]), angle
              )
          kwargs = self.Q.polykw
          kwargs.update(self.kw)
          self.vector = mcollections.PolyCollection(
              self.verts,
              offsets=[(self.X, self.Y)],
              offset_transform=self.get_transform(),
              **kwargs,
          )
          if self.color is not None:
              self.vector.set_color(self.color)
          self.vector.set_transform(self.Q.get_transform())
          self.vector.set_figure(self.get_figure())
          self._dpi_at_last_init = self.Q.axes.figure.dpi
  
imports: import math
  import numpy
  from numpy import ma
  from matplotlib import _api, cbook, _docstring
  import matplotlib.artist
  import matplotlib.collections
  from matplotlib.patches import CirclePolygon
  import matplotlib.text
  import matplotlib.transforms
label_desc: Use image node_id 3 for calling the QuiverKey obj's underlying member method code with example usage: obj._init() without return types