matplotlibで、特定のaxeのみをサイズ変更する

Axesクラスのset_position methodを使う。

以下pydoc

Help on method set_position in pylab.Axes:

pylab.Axes.set_position = set_position(self, pos, which='both') unbound matplotlib.axes.Axes method
    Set the axes position with::

      pos = [left, bottom, width, height]

    in relative 0,1 coords, or *pos* can be a
    :class:`~matplotlib.transforms.Bbox`

    There are two position variables: one which is ultimately
    used, but which may be modified by :meth:`apply_aspect`, and a
    second which is the starting point for :meth:`apply_aspect`.


    Optional keyword arguments:
      *which*

        ==========   ====================
        value        description
        ==========   ====================
        'active'     to change the first
        'original'   to change the second
        'both'       to change both
        ==========   ====================