matplotlib & pandas

Python/matplotlab/gallery/event_handling/path_editor.md

@@ -0,0 +1,164 @@
+# 路径编辑器
+
+跨GUI共享事件。
+
+此示例演示了使用Matplotlib事件处理与画布上的对象进行交互和修改对象的跨GUI应用程序。
+
+![路径编辑器示例](https://matplotlib.org/_images/sphx_glr_path_editor_001.png)
+
+```python
+import numpy as np
+import matplotlib.path as mpath
+import matplotlib.patches as mpatches
+import matplotlib.pyplot as plt
+
+Path = mpath.Path
+
+fig, ax = plt.subplots()
+
+pathdata = [
+    (Path.MOVETO, (1.58, -2.57)),
+    (Path.CURVE4, (0.35, -1.1)),
+    (Path.CURVE4, (-1.75, 2.0)),
+    (Path.CURVE4, (0.375, 2.0)),
+    (Path.LINETO, (0.85, 1.15)),
+    (Path.CURVE4, (2.2, 3.2)),
+    (Path.CURVE4, (3, 0.05)),
+    (Path.CURVE4, (2.0, -0.5)),
+    (Path.CLOSEPOLY, (1.58, -2.57)),
+    ]
+
+codes, verts = zip(*pathdata)
+path = mpath.Path(verts, codes)
+patch = mpatches.PathPatch(path, facecolor='green', edgecolor='yellow', alpha=0.5)
+ax.add_patch(patch)
+
+
+class PathInteractor(object):
+    """
+    An path editor.
+
+    Key-bindings
+
+      't' toggle vertex markers on and off.  When vertex markers are on,
+          you can move them, delete them
+
+
+    """
+
+    showverts = True
+    epsilon = 5  # max pixel distance to count as a vertex hit
+
+    def __init__(self, pathpatch):
+
+        self.ax = pathpatch.axes
+        canvas = self.ax.figure.canvas
+        self.pathpatch = pathpatch
+        self.pathpatch.set_animated(True)
+
+        x, y = zip(*self.pathpatch.get_path().vertices)
+
+        self.line, = ax.plot(x, y, marker='o', markerfacecolor='r', animated=True)
+
+        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.pathpatch)
+        self.ax.draw_artist(self.line)
+        self.canvas.blit(self.ax.bbox)
+
+    def pathpatch_changed(self, pathpatch):
+        'this method is called whenever the pathpatchgon object is called'
+        # only copy the artist props to the line (except visibility)
+        vis = self.line.get_visible()
+        plt.Artist.update_from(self.line, pathpatch)
+        self.line.set_visible(vis)  # don't use the pathpatch 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.pathpatch.get_path().vertices)
+        xyt = self.pathpatch.get_transform().transform(xy)
+        xt, yt = xyt[:, 0], xyt[:, 1]
+        d = np.sqrt((xt - event.x)**2 + (yt - event.y)**2)
+        ind = d.argmin()
+
+        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
+
+        self.canvas.draw()
+
+    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
+
+        vertices = self.pathpatch.get_path().vertices
+
+        vertices[self._ind] = x, y
+        self.line.set_data(zip(*vertices))
+
+        self.canvas.restore_region(self.background)
+        self.ax.draw_artist(self.pathpatch)
+        self.ax.draw_artist(self.line)
+        self.canvas.blit(self.ax.bbox)
+
+
+interactor = PathInteractor(patch)
+ax.set_title('drag vertices to update path')
+ax.set_xlim(-3, 4)
+ax.set_ylim(-3, 4)
+
+plt.show()
+```
+
+## 下载这个示例
+            
+- [下载python源码: path_editor.py](https://matplotlib.org/_downloads/path_editor.py)
+- [下载Jupyter notebook: path_editor.ipynb](https://matplotlib.org/_downloads/path_editor.ipynb)