matplotlib & pandas

Python/matplotlab/gallery/event_handling/poly_editor.md

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+# 综合编辑器
+
+这是一个示例，展示如何使用Matplotlib事件处理来构建跨GUI应用程序，以与画布上的对象进行交互。
+
+![综合编辑器示例](https://matplotlib.org/_images/sphx_glr_poly_editor_001.png)
+
+```python
+import numpy as np
+from matplotlib.lines import Line2D
+from matplotlib.artist import Artist
+from matplotlib.mlab import dist_point_to_segment
+
+
+class PolygonInteractor(object):
+    """
+    A polygon editor.
+
+    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):
+        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
+
+        x, y = zip(*self.poly.xy)
+        self.line = Line2D(x, y,
+                           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
+
+    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)
+        # 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))
+
+        self.canvas.restore_region(self.background)
+        self.ax.draw_artist(self.poly)
+        self.ax.draw_artist(self.line)
+        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)
+
+    poly = Polygon(np.column_stack([xs, ys]), animated=True)
+
+    fig, ax = plt.subplots()
+    ax.add_patch(poly)
+    p = PolygonInteractor(ax, poly)
+
+    ax.set_title('Click and drag a point to move it')
+    ax.set_xlim((-2, 2))
+    ax.set_ylim((-2, 2))
+    plt.show()
+```
+
+## 下载这个示例
+            
+- [下载python源码: poly_editor.py](https://matplotlib.org/_downloads/poly_editor.py)
+- [下载Jupyter notebook: poly_editor.ipynb](https://matplotlib.org/_downloads/poly_editor.ipynb)