从 matplotlib 3.1 开始，有一个方向关键字。在 matplotlib 3.1 之前，这是不可能开箱即用的，因为 matplotlib.widgets.Slider 实现使用 axvspan 和 axvline 来定义滑块（这是一个 patches.Polygon），并根据水平假设对其进行了更新。
如果你还在使用旧版本的matplotlib，以水平滑块为例编写你自己的垂直滑块并不难（你也可以从AxesWidget子类化），但必须自己完成.
自 matplotlib 2.0 起有效： 下面给出了一个垂直滑块类；它就像水平的一样工作，除了它是......好吧......垂直！
from matplotlib.widgets import AxesWidget
import six
class VertSlider(AxesWidget):
"""
A slider representing a floating point range.
For the slider to remain responsive you must maintain a
reference to it.
The following attributes are defined
*ax* : the slider :class:`matplotlib.axes.Axes` instance
*val* : the current slider value
*hline* : a :class:`matplotlib.lines.Line2D` instance
representing the initial value of the slider
*poly* : A :class:`matplotlib.patches.Polygon` instance
which is the slider knob
*valfmt* : the format string for formatting the slider text
*label* : a :class:`matplotlib.text.Text` instance
for the slider label
*closedmin* : whether the slider is closed on the minimum
*closedmax* : whether the slider is closed on the maximum
*slidermin* : another slider - if not *None*, this slider must be
greater than *slidermin*
*slidermax* : another slider - if not *None*, this slider must be
less than *slidermax*
*dragging* : allow for mouse dragging on slider
Call :meth:`on_changed` to connect to the slider event
"""
def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt='%1.2f',
closedmin=True, closedmax=True, slidermin=None,
slidermax=None, dragging=True, **kwargs):
"""
Create a slider from *valmin* to *valmax* in axes *ax*.
Additional kwargs are passed on to ``self.poly`` which is the
:class:`matplotlib.patches.Rectangle` which draws the slider
knob. See the :class:`matplotlib.patches.Rectangle` documentation
valid property names (e.g., *facecolor*, *edgecolor*, *alpha*, ...).
Parameters
----------
ax : Axes
The Axes to put the slider in
label : str
Slider label
valmin : float
The minimum value of the slider
valmax : float
The maximum value of the slider
valinit : float
The slider initial position
label : str
The slider label
valfmt : str
Used to format the slider value, fprint format string
closedmin : bool
Indicate whether the slider interval is closed on the bottom
closedmax : bool
Indicate whether the slider interval is closed on the top
slidermin : Slider or None
Do not allow the current slider to have a value less than
`slidermin`
slidermax : Slider or None
Do not allow the current slider to have a value greater than
`slidermax`
dragging : bool
if the slider can be dragged by the mouse
"""
AxesWidget.__init__(self, ax)
self.valmin = valmin
self.valmax = valmax
self.val = valinit
self.valinit = valinit
self.poly = ax.axhspan(valmin, valinit, 0, 1, **kwargs)
self.hline = ax.axhline(valinit, 0, 1, color='r', lw=1)
self.valfmt = valfmt
ax.set_xticks([])
ax.set_ylim((valmin, valmax))
ax.set_yticks([])
ax.set_navigate(False)
self.connect_event('button_press_event', self._update)
self.connect_event('button_release_event', self._update)
if dragging:
self.connect_event('motion_notify_event', self._update)
self.label = ax.text(0.5, 1.03, label, transform=ax.transAxes,
verticalalignment='center',
horizontalalignment='center')
self.valtext = ax.text(0.5, -0.03, valfmt % valinit,
transform=ax.transAxes,
verticalalignment='center',
horizontalalignment='center')
self.cnt = 0
self.observers = {}
self.closedmin = closedmin
self.closedmax = closedmax
self.slidermin = slidermin
self.slidermax = slidermax
self.drag_active = False
def _update(self, event):
"""update the slider position"""
if self.ignore(event):
return
if event.button != 1:
return
if event.name == 'button_press_event' and event.inaxes == self.ax:
self.drag_active = True
event.canvas.grab_mouse(self.ax)
if not self.drag_active:
return
elif ((event.name == 'button_release_event') or
(event.name == 'button_press_event' and
event.inaxes != self.ax)):
self.drag_active = False
event.canvas.release_mouse(self.ax)
return
val = event.ydata
if val <= self.valmin:
if not self.closedmin:
return
val = self.valmin
elif val >= self.valmax:
if not self.closedmax:
return
val = self.valmax
if self.slidermin is not None and val <= self.slidermin.val:
if not self.closedmin:
return
val = self.slidermin.val
if self.slidermax is not None and val >= self.slidermax.val:
if not self.closedmax:
return
val = self.slidermax.val
self.set_val(val)
def set_val(self, val):
xy = self.poly.xy
xy[1] = 0, val
xy[2] = 1, val
self.poly.xy = xy
self.valtext.set_text(self.valfmt % val)
if self.drawon:
self.ax.figure.canvas.draw_idle()
self.val = val
if not self.eventson:
return
for cid, func in six.iteritems(self.observers):
func(val)
def on_changed(self, func):
"""
When the slider value is changed, call *func* with the new
slider position
A connection id is returned which can be used to disconnect
"""
cid = self.cnt
self.observers[cid] = func
self.cnt += 1
return cid
def disconnect(self, cid):
"""remove the observer with connection id *cid*"""
try:
del self.observers[cid]
except KeyError:
pass
def reset(self):
"""reset the slider to the initial value if needed"""
if (self.val != self.valinit):
self.set_val(self.valinit)