Matplotlib交互式拖动重叠点

Question

就我而言，每次只想拖一个点。但是，由于两个点严重重叠，因此拖动一个点将导致另一个点被拖动。我如何只拖动上面的点？谢谢！

from pylab import *
from scipy import *
import matplotlib.pyplot as plt
import matplotlib.patches as patches


class DraggablePoint:
    def __init__(self, p):
        self.point = p
        self.press = None

    def connect(self):
        self.cidpress = self.point.figure.canvas.mpl_connect('button_press_event', self.button_press_event)
        self.cidrelease = self.point.figure.canvas.mpl_connect('button_release_event', self.button_release_event)
        self.cidmotion = self.point.figure.canvas.mpl_connect('motion_notify_event', self.motion_notify_event)

    def disconnect(self):
    'disconnect all the stored connection ids'
        self.point.figure.canvas.mpl_disconnect(self.cidpress)
        self.point.figure.canvas.mpl_disconnect(self.cidrelease)
        self.point.figure.canvas.mpl_disconnect(self.cidmotion)


    def button_press_event(self,event):
        if event.inaxes != self.point.axes:
            return
        contains = self.point.contains(event)[0]
        if not contains: return
        self.press = self.point.center, event.xdata, event.ydata


    def button_release_event(self,event):
        self.press = None
        self.point.figure.canvas.draw()

    def motion_notify_event(self, event):
        if self.press is None: return
        if event.inaxes != self.point.axes: return
        self.point.center, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress 
        self.point.center = (self.point.center[0]+dx, self.point.center[1]+dy)
        print self.point.center
        self.point.figure.canvas.draw()

if __name__ == '__main__':
    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.set_xlim(-1,2)
    ax.set_ylim(-1,2)
    circles = []
    circle1 = patches.Circle((0.32,0.3), 0.2, fc='r', alpha=0.5, picker=True)
    circle = patches.Circle((0.3,0.3), 0.2, fc='b', alpha=0.5, picker=True)
    circles.append(ax.add_patch(circle1))
    circles.append(ax.add_patch(circle))
    drs = []
    for c in circles:
        #print c.center[0]    
        dr = DraggablePoint(c)
        dr.connect()   
        drs.append(dr) 
    plt.show()

Answer 1

Joe的方法工作正常，但是它使一组可拖动点作为一个类，而不是单个可拖动点类。我只是遇到了一种使用动画blit技术解决上述问题的替代方法。它不仅使拖动更快，更流畅，而且只能拖动一个点。请参阅以下代码。

import matplotlib.pyplot as plt
import matplotlib.patches as patches
class DraggablePoint:
    lock = None #only one can be animated at a time
    def __init__(self, point):
        self.point = point
        self.press = None
        self.background = None

    def connect(self):
        'connect to all the events we need'
        self.cidpress = self.point.figure.canvas.mpl_connect('button_press_event', self.on_press)
        self.cidrelease = self.point.figure.canvas.mpl_connect('button_release_event', self.on_release)
        self.cidmotion = self.point.figure.canvas.mpl_connect('motion_notify_event', self.on_motion)

    def on_press(self, event):
        if event.inaxes != self.point.axes: return
        if DraggablePoint.lock is not None: return
        contains, attrd = self.point.contains(event)
        if not contains: return
        self.press = (self.point.center), event.xdata, event.ydata
        DraggablePoint.lock = self

        # draw everything but the selected rectangle and store the pixel buffer
        canvas = self.point.figure.canvas
        axes = self.point.axes
        self.point.set_animated(True)
        canvas.draw()
        self.background = canvas.copy_from_bbox(self.point.axes.bbox)

        # now redraw just the rectangle
        axes.draw_artist(self.point)

        # and blit just the redrawn area
        canvas.blit(axes.bbox)

    def on_motion(self, event):
        if DraggablePoint.lock is not self:
            return
        if event.inaxes != self.point.axes: return
        self.point.center, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress
        self.point.center = (self.point.center[0]+dx, self.point.center[1]+dy)

        canvas = self.point.figure.canvas
        axes = self.point.axes
        # restore the background region
        canvas.restore_region(self.background)

        # redraw just the current rectangle
        axes.draw_artist(self.point)

        # blit just the redrawn area
        canvas.blit(axes.bbox)

    def on_release(self, event):
        'on release we reset the press data'
        if DraggablePoint.lock is not self:
            return

        self.press = None
        DraggablePoint.lock = None

        # turn off the rect animation property and reset the background
        self.point.set_animated(False)
        self.background = None

        # redraw the full figure
        self.point.figure.canvas.draw()

    def disconnect(self):
        'disconnect all the stored connection ids'
        self.point.figure.canvas.mpl_disconnect(self.cidpress)
        self.point.figure.canvas.mpl_disconnect(self.cidrelease)
        self.point.figure.canvas.mpl_disconnect(self.cidmotion)

fig = plt.figure()
ax = fig.add_subplot(111)
drs = []
circles = [patches.Circle((0.32, 0.3), 0.03, fc='r', alpha=0.5),
               patches.Circle((0.3,0.3), 0.03, fc='g', alpha=0.5)]

for circ in circles:
    ax.add_patch(circ)
    dr = DraggablePoint(circ)
    dr.connect()
    drs.append(dr)

plt.show()