Python中的交互式BSpline拟合

Python中的交互式BSpline拟合

当然，您需要将功能添加到中

PolygonInteractor

。但是不要让它自己绘制任何东西。然后在类中添加新行，

self.line2

这将是要更新的行。

最后，让全班同学也为您画一条新线。并使用插值函数的结果更新它。

为了方便起见，您可以将“多边形（

self.poly

）”设置为不可见，也可以从中删除该线，

self.line

并且仅显示点可能有意义。

import numpy as npfrom  scipy.interpolate import interp1dfrom matplotlib.lines import Line2Dfrom matplotlib.artist import Artistfrom matplotlib.mlab import dist_point_to_segmentclass PolygonInteractor(object):    """    A polygon editor.    https://matplotlib.org/gallery/event_handling/poly_editor.html    Key-bindings      't' toggle vertex markers on and off.  When vertex markers are on,          you can move them, delete them      'd' delete the vertex under point      'i' insert a vertex at point.  You must be within epsilon of the          line connecting two existing vertices    """    showverts = True    epsilon = 5  # max pixel distance to count as a vertex hit    def __init__(self, ax, poly, visible=False):        if poly.figure is None: raise RuntimeError('You must first add the polygon to a figure '         'or canvas before defining the interactor')        self.ax = ax        canvas = poly.figure.canvas        self.poly = poly        self.poly.set_visible(visible)        x, y = zip(*self.poly.xy)        self.line = Line2D(x, y, ls="",     marker='o', markerfacecolor='r',     animated=True)        self.ax.add_line(self.line)        self.cid = self.poly.add_callback(self.poly_changed)        self._ind = None  # the active vert        canvas.mpl_connect('draw_event', self.draw_callback)        canvas.mpl_connect('button_press_event', self.button_press_callback)        canvas.mpl_connect('key_press_event', self.key_press_callback)        canvas.mpl_connect('button_release_event', self.button_release_callback)        canvas.mpl_connect('motion_notify_event', self.motion_notify_callback)        self.canvas = canvas        x,y = self.interpolate()        self.line2 = Line2D(x, y, animated=True)        self.ax.add_line(self.line2)    def interpolate(self):        x, y = self.poly.xy[:].T        i = np.arange(len(x))        interp_i = np.linspace(0, i.max(), 100 * i.max())        xi = interp1d(i, x, kind='cubic')(interp_i)          yi = interp1d(i, y, kind='cubic')(interp_i)        return xi,yi    def draw_callback(self, event):        self.background = self.canvas.copy_from_bbox(self.ax.bbox)        self.ax.draw_artist(self.poly)        self.ax.draw_artist(self.line)        self.ax.draw_artist(self.line2)        # do not need to blit here, this will fire before the screen is        # updated    def poly_changed(self, poly):        'this method is called whenever the polygon object is called'        # only copy the artist props to the line (except visibility)        vis = self.line.get_visible()        Artist.update_from(self.line, poly)        self.line.set_visible(vis)  # don't use the poly visibility state    def get_ind_under_point(self, event):        'get the index of the vertex under point if within epsilon tolerance'        # display coords        xy = np.asarray(self.poly.xy)        xyt = self.poly.get_transform().transform(xy)        xt, yt = xyt[:, 0], xyt[:, 1]        d = np.hypot(xt - event.x, yt - event.y)        indseq, = np.nonzero(d == d.min())        ind = indseq[0]        if d[ind] >= self.epsilon: ind = None        return ind    def button_press_callback(self, event):        'whenever a mouse button is pressed'        if not self.showverts: return        if event.inaxes is None: return        if event.button != 1: return        self._ind = self.get_ind_under_point(event)    def button_release_callback(self, event):        'whenever a mouse button is released'        if not self.showverts: return        if event.button != 1: return        self._ind = None    def key_press_callback(self, event):        'whenever a key is pressed'        if not event.inaxes: return        if event.key == 't': self.showverts = not self.showverts self.line.set_visible(self.showverts) if not self.showverts:     self._ind = None        elif event.key == 'd': ind = self.get_ind_under_point(event) if ind is not None:     self.poly.xy = np.delete(self.poly.xy,        ind, axis=0)     self.line.set_data(zip(*self.poly.xy))        elif event.key == 'i': xys = self.poly.get_transform().transform(self.poly.xy) p = event.x, event.y  # display coords for i in range(len(xys) - 1):     s0 = xys[i]     s1 = xys[i + 1]     d = dist_point_to_segment(p, s0, s1)     if d <= self.epsilon:         self.poly.xy = np.insert(  self.poly.xy, i+1,  [event.xdata, event.ydata],  axis=0)         self.line.set_data(zip(*self.poly.xy))         break        if self.line.stale: self.canvas.draw_idle()    def motion_notify_callback(self, event):        'on mouse movement'        if not self.showverts: return        if self._ind is None: return        if event.inaxes is None: return        if event.button != 1: return        x, y = event.xdata, event.ydata        self.poly.xy[self._ind] = x, y        if self._ind == 0: self.poly.xy[-1] = x, y        elif self._ind == len(self.poly.xy) - 1: self.poly.xy[0] = x, y        self.line.set_data(zip(*self.poly.xy))        x,y = self.interpolate()        self.line2.set_data(x,y)        self.canvas.restore_region(self.background)        self.ax.draw_artist(self.poly)        self.ax.draw_artist(self.line)        self.ax.draw_artist(self.line2)        self.canvas.blit(self.ax.bbox)if __name__ == '__main__':    import matplotlib.pyplot as plt    from matplotlib.patches import Polygon    #theta = np.arange(0, 2*np.pi, 0.1)    #r = 1.5    #xs = r*np.cos(theta)    #ys = r*np.sin(theta)    xs = (921, 951, 993, 1035, 1065, 1045, 993, 945)    ys = (1181, 1230, 1243, 1230, 1181, 1130, 1130, 1130)    poly = Polygon(list(zip(xs, ys)), animated=True)    fig, ax = plt.subplots()    ax.add_patch(poly)    p = PolygonInteractor(ax, poly, visible=False)    ax.set_title('Click and drag a point to move it')    ax.set_xlim((800, 1300))    ax.set_ylim((1000, 1300))    plt.show()

请注意，此处创建的曲线不是真正的循环。它有一个起点，曲线并不真正平滑。可以通过使用贝塞尔曲线的真循环集来避免这种情况，如使用matplotlib创建随机形状/轮廓所示。