code: def do_constrained_layout(
      fig, renderer, h_pad, w_pad, hspace=None, wspace=None
  ):
      """
      Do the constrained_layout.  Called at draw time in
       ``figure.constrained_layout()``
  
      Parameters
      ----------
  
  
      fig: Figure
        is the ``figure`` instance to do the layout in.
  
      renderer: Renderer
        the renderer to use.
  
       h_pad, w_pad : float
         are in figure-normalized units, and are a padding around the axes
         elements.
  
       hspace, wspace : float
          are in fractions of the subplot sizes.
  
      """
  
      """  Steps:
  
      1. get a list of unique gridspecs in this figure.  Each gridspec will be
      constrained separately.
      2. Check for gaps in the gridspecs.  i.e. if not every axes slot in the
      gridspec has been filled.  If empty, add a ghost axis that is made so
      that it cannot be seen (though visible=True).  This is needed to make
      a blank spot in the layout.
      3. Compare the tight_bbox of each axes to its `position`, and assume that
      the difference is the space needed by the elements around the edge of
      the axes (decorations) like the title, ticklabels, x-labels, etc.  This
      can include legends who overspill the axes boundaries.
      4. Constrain gridspec elements to line up:
          a) if colnum0 neq colnumC, the two subplotspecs are stacked next to
          each other, with the appropriate order.
          b) if colnum0 == columnC line up the left or right side of the
          _poslayoutbox (depending if it is the min or max num that is equal).
          c) do the same for rows...
      5. The above doesn't constrain relative sizes of the _poslayoutboxes at
      all, and indeed zero-size is a solution that the solver often finds more
      convenient than expanding the sizes.  Right now the solution is to compare
      subplotspec sizes (i.e. drowsC and drows0) and constrain the larger
      _poslayoutbox to be larger than the ratio of the sizes.  i.e. if drows0 >
      drowsC,  then ax._poslayoutbox > axc._poslayoutbox * drowsC / drows0. This
      works fine *if* the decorations are similar between the axes.  If the
      larger subplotspec has much larger axes decorations, then the constraint
      above is incorrect.
  
      We need the greater than in the above, in general, rather than an equals
      sign.  Consider the case of the left column having 2 rows, and the right
      column having 1 row.  We want the top and bottom of the _poslayoutboxes to
      line up. So that means if there are decorations on the left column axes
      they will be smaller than half as large as the right hand axis.
  
      This can break down if the decoration size for the right hand axis (the
      margins) is very large.  There must be a math way to check for this case.
  
      """
  
      invTransFig = fig.transFigure.inverted().transform_bbox
  
      # list of unique gridspecs that contain child axes:
      gss = set([])
      for ax in fig.axes:
          if hasattr(ax, "get_subplotspec"):
              gs = ax.get_subplotspec().get_gridspec()
              if gs._layoutbox is not None:
                  gss.add(gs)
      if len(gss) == 0:
          warnings.warn(
              "There are no gridspecs with layoutboxes. "
              "Possibly did not call parent GridSpec with the figure= "
              "keyword"
          )
  
      # check for unoccupied gridspec slots and make ghost axes for these
      # slots...  Do for each gs separately.  This is a pretty big kludge
      # but shoudn't have too much ill effect.  The worst is that
      # someone querrying the figure will wonder why there are more
      # axes than they thought.
      if fig._layoutbox.constrained_layout_called < 1:
          for gs in gss:
              nrows, ncols = gs.get_geometry()
              hassubplotspec = np.zeros(nrows * ncols, dtype=bool)
              axs = []
              for ax in fig.axes:
                  if (
                      hasattr(ax, "get_subplotspec")
                      and ax._layoutbox is not None
                      and ax.get_subplotspec().get_gridspec() == gs
                  ):
                      axs += [ax]
              for ax in axs:
                  ss0 = ax.get_subplotspec()
                  if ss0.num2 is None:
                      ss0.num2 = ss0.num1
                  hassubplotspec[ss0.num1 : (ss0.num2 + 1)] = True
              for nn, hss in enumerate(hassubplotspec):
                  if not hss:
                      # this gridspec slot doesn't have an axis so we
                      # make a "ghost".
                      ax = fig.add_subplot(gs[nn])
                      ax.set_frame_on(False)
                      ax.set_xticks([])
                      ax.set_yticks([])
                      ax.set_facecolor((1, 0, 0, 0))
  
      # for each axes, make a margin between the *pos* layoutbox and the
      # *axes* layoutbox be a minimum size that can accomodate the
      # decorations on the axis.
      for ax in fig.axes:
          _log.debug(ax._layoutbox)
          if ax._layoutbox is not None:
              pos = ax.get_position(original=True)
              tightbbox = get_axall_tightbbox(ax, renderer)
              bbox = invTransFig(tightbbox)
              # use stored h_pad if it exists
              h_padt = ax._poslayoutbox.h_pad
              if h_padt is None:
                  h_padt = h_pad
              w_padt = ax._poslayoutbox.w_pad
              if w_padt is None:
                  w_padt = w_pad
              ax._poslayoutbox.edit_left_margin_min(
                  -bbox.x0 + pos.x0 + w_padt
              )
              ax._poslayoutbox.edit_right_margin_min(
                  bbox.x1 - pos.x1 + w_padt
              )
              ax._poslayoutbox.edit_bottom_margin_min(
                  -bbox.y0 + pos.y0 + h_padt
              )
              ax._poslayoutbox.edit_top_margin_min(
                  bbox.y1 - pos.y1 + h_padt
              )
              _log.debug("left %f", (-bbox.x0 + pos.x0 + w_pad))
              _log.debug("right %f", (bbox.x1 - pos.x1 + w_pad))
              _log.debug("bottom %f", (-bbox.y0 + pos.y0 + h_padt))
              # Sometimes its possible for the solver to collapse
              # rather than expand axes, so they all have zero height
              # or width.  This stops that...  It *should* have been
              # taken into account w/ pref_width...
              if fig._layoutbox.constrained_layout_called < 1:
                  ax._poslayoutbox.constrain_height_min(
                      20, strength="weak"
                  )
                  ax._poslayoutbox.constrain_width_min(
                      20, strength="weak"
                  )
                  ax._layoutbox.constrain_height_min(
                      20, strength="weak"
                  )
                  ax._layoutbox.constrain_width_min(20, strength="weak")
                  ax._poslayoutbox.constrain_top_margin(
                      0, strength="weak"
                  )
                  ax._poslayoutbox.constrain_bottom_margin(
                      0, strength="weak"
                  )
                  ax._poslayoutbox.constrain_right_margin(
                      0, strength="weak"
                  )
                  ax._poslayoutbox.constrain_left_margin(
                      0, strength="weak"
                  )
  
      # do layout for suptitle.
      if (
          fig._suptitle is not None
          and fig._suptitle._layoutbox is not None
      ):
          sup = fig._suptitle
          bbox = invTransFig(sup.get_window_extent(renderer=renderer))
          height = bbox.y1 - bbox.y0
          sup._layoutbox.edit_height(height + h_pad)
  
      # OK, the above lines up ax._poslayoutbox with ax._layoutbox
      # now we need to
      #   1) arrange the subplotspecs.  We do it at this level because
      #      the subplotspecs are meant to contain other dependent axes
      #      like colorbars or legends.
      #   2) line up the right and left side of the ax._poslayoutbox
      #      that have the same subplotspec maxes.
  
      if fig._layoutbox.constrained_layout_called < 1:
          # arrange the subplotspecs...  This is all done relative to each
          # other.  Some subplotspecs conatain axes, and others contain gridspecs
          # the ones that contain gridspecs are a set proportion of their
          # parent gridspec.  The ones that contain axes are not so constrained.
          figlb = fig._layoutbox
          for child in figlb.children:
              if child._is_gridspec_layoutbox():
                  # farm the gridspec layout out.
                  #
                  # This routine makes all the subplot spec containers
                  # have the correct arrangement.  It just stacks the
                  # subplot layoutboxes in the correct order...
                  _arange_subplotspecs(
                      child, hspace=hspace, wspace=wspace
                  )
  
          # - Align right/left and bottom/top spines of appropriate subplots.
          # - Compare size of subplotspec including height and width ratios
          #   and make sure that the axes spines are at least as large
          #   as they should be.
          for gs in gss:
              # for each gridspec...
              nrows, ncols = gs.get_geometry()
              width_ratios = gs.get_width_ratios()
              height_ratios = gs.get_height_ratios()
              if width_ratios is None:
                  width_ratios = np.ones(ncols)
              if height_ratios is None:
                  height_ratios = np.ones(nrows)
  
              # get axes in this gridspec....
              axs = []
              for ax in fig.axes:
                  if (
                      hasattr(ax, "get_subplotspec")
                      and ax._layoutbox is not None
                  ):
                      if ax.get_subplotspec().get_gridspec() == gs:
                          axs += [ax]
              rownummin = np.zeros(len(axs), dtype=np.int8)
              rownummax = np.zeros(len(axs), dtype=np.int8)
              colnummin = np.zeros(len(axs), dtype=np.int8)
              colnummax = np.zeros(len(axs), dtype=np.int8)
              width = np.zeros(len(axs))
              height = np.zeros(len(axs))
  
              for n, ax in enumerate(axs):
                  ss0 = ax.get_subplotspec()
                  if ss0.num2 is None:
                      ss0.num2 = ss0.num1
                  rownummin[n], colnummin[n] = divmod(ss0.num1, ncols)
                  rownummax[n], colnummax[n] = divmod(ss0.num2, ncols)
                  width[n] = np.sum(
                      width_ratios[colnummin[n] : (colnummax[n] + 1)]
                  )
                  height[n] = np.sum(
                      height_ratios[rownummin[n] : (rownummax[n] + 1)]
                  )
  
              for nn, ax in enumerate(axs[:-1]):
                  ss0 = ax.get_subplotspec()
  
                  # now compare ax to all the axs:
                  #
                  # If the subplotspecs have the same colnumXmax, then line
                  # up their right sides.  If they have the same min, then
                  # line up their left sides (and vertical equivalents).
                  rownum0min, colnum0min = rownummin[nn], colnummin[nn]
                  rownum0max, colnum0max = rownummax[nn], colnummax[nn]
                  width0, height0 = width[nn], height[nn]
                  alignleft = False
                  alignright = False
                  alignbot = False
                  aligntop = False
                  alignheight = False
                  alignwidth = False
                  for mm in range(nn + 1, len(axs)):
                      axc = axs[mm]
                      rownumCmin, colnumCmin = (
                          rownummin[mm],
                          colnummin[mm],
                      )
                      rownumCmax, colnumCmax = (
                          rownummax[mm],
                          colnummax[mm],
                      )
                      widthC, heightC = width[mm], height[mm]
                      # Horizontally align axes spines if they have the
                      # same min or max:
                      if not alignleft and colnum0min == colnumCmin:
                          # we want the _poslayoutboxes to line up on left
                          # side of the axes spines...
                          layoutbox.align(
                              [ax._poslayoutbox, axc._poslayoutbox],
                              "left",
                          )
                          alignleft = True
  
                      if not alignright and colnum0max == colnumCmax:
                          # line up right sides of _poslayoutbox
                          layoutbox.align(
                              [ax._poslayoutbox, axc._poslayoutbox],
                              "right",
                          )
                          alignright = True
                      # Vertically align axes spines if they have the
                      # same min or max:
                      if not aligntop and rownum0min == rownumCmin:
                          # line up top of _poslayoutbox
                          _log.debug("rownum0min == rownumCmin")
                          layoutbox.align(
                              [ax._poslayoutbox, axc._poslayoutbox],
                              "top",
                          )
                          aligntop = True
  
                      if not alignbot and rownum0max == rownumCmax:
                          # line up bottom of _poslayoutbox
                          _log.debug("rownum0max == rownumCmax")
                          layoutbox.align(
                              [ax._poslayoutbox, axc._poslayoutbox],
                              "bottom",
                          )
                          alignbot = True
                      ###########
                      # Now we make the widths and heights of position boxes
                      # similar. (i.e the spine locations)
                      # This allows vertically stacked subplots to have
                      # different sizes if they occupy different amounts
                      # of the gridspec:  i.e.
                      # gs = gridspec.GridSpec(3,1)
                      # ax1 = gs[0,:]
                      # ax2 = gs[1:,:]
                      # then drows0 = 1, and drowsC = 2, and ax2
                      # should be at least twice as large as ax1.
                      # But it can be more than twice as large because
                      # it needs less room for the labeling.
                      #
                      # For height, this only needs to be done if the
                      # subplots share a column.  For width if they
                      # share a row.
  
                      drowsC = rownumCmax - rownumCmin + 1
                      drows0 = rownum0max - rownum0min + 1
                      dcolsC = colnumCmax - colnumCmin + 1
                      dcols0 = colnum0max - colnum0min + 1
  
                      if not alignheight and drows0 == drowsC:
                          ax._poslayoutbox.constrain_height(
                              axc._poslayoutbox.height
                              * height0
                              / heightC
                          )
                          alignheight = True
                      elif in_same_column(
                          colnum0min, colnum0max, colnumCmin, colnumCmax
                      ):
                          if height0 > heightC:
                              ax._poslayoutbox.constrain_height_min(
                                  axc._poslayoutbox.height
                                  * height0
                                  / heightC
                              )
                              # these constraints stop the smaller axes from
                              # being allowed to go to zero height...
                              axc._poslayoutbox.constrain_height_min(
                                  ax._poslayoutbox.height
                                  * heightC
                                  / (height0 * 1.8)
                              )
                          elif height0 < heightC:
                              axc._poslayoutbox.constrain_height_min(
                                  ax._poslayoutbox.height
                                  * heightC
                                  / height0
                              )
                              ax._poslayoutbox.constrain_height_min(
                                  ax._poslayoutbox.height
                                  * height0
                                  / (heightC * 1.8)
                              )
                      # widths...
                      if not alignwidth and dcols0 == dcolsC:
                          ax._poslayoutbox.constrain_width(
                              axc._poslayoutbox.width * width0 / widthC
                          )
                          alignwidth = True
                      elif in_same_row(
                          rownum0min, rownum0max, rownumCmin, rownumCmax
                      ):
                          if width0 > widthC:
                              ax._poslayoutbox.constrain_width_min(
                                  axc._poslayoutbox.width
                                  * width0
                                  / widthC
                              )
                              axc._poslayoutbox.constrain_width_min(
                                  ax._poslayoutbox.width
                                  * widthC
                                  / (width0 * 1.8)
                              )
                          elif width0 < widthC:
                              axc._poslayoutbox.constrain_width_min(
                                  ax._poslayoutbox.width
                                  * widthC
                                  / width0
                              )
                              ax._poslayoutbox.constrain_width_min(
                                  axc._poslayoutbox.width
                                  * width0
                                  / (widthC * 1.8)
                              )
  
      fig._layoutbox.constrained_layout_called += 1
      fig._layoutbox.update_variables()
      # Now set the position of the axes...
      for ax in fig.axes:
          if ax._layoutbox is not None:
              newpos = ax._poslayoutbox.get_rect()
              _log.debug("newpos %r", newpos)
              # Now set the new position.
              # ax.set_position will zero out the layout for
              # this axis, allowing users to hard-code the position,
              # so this does the same w/o zeroing layout.
              ax._set_position(newpos, which="original")
  
file_path: catboost/contrib/python/matplotlib/py2/matplotlib/_constrained_layout.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import numpy
  import logging
  import warnings
  from matplotlib.legend import Legend
  import matplotlib.transforms
  import matplotlib._layoutbox
label_desc: Use image node_id 4 for calling a global function with example usage: do_constrained_layout(fig, renderer, h_pad, w_pad, hspace, wspace) without return types