matplotlib & pandas

Python/matplotlab/gallery/event_handling/viewlims.md

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+# Viewlims
+
+创建两个相同的面板。在右侧面板上放大将在第一个面板中显示一个矩形，表示缩放的区域。
+
+![Viewlims](https://matplotlib.org/_images/sphx_glr_viewlims_001.png)
+
+```python
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib.patches import Rectangle
+
+
+# We just subclass Rectangle so that it can be called with an Axes
+# instance, causing the rectangle to update its shape to match the
+# bounds of the Axes
+class UpdatingRect(Rectangle):
+    def __call__(self, ax):
+        self.set_bounds(*ax.viewLim.bounds)
+        ax.figure.canvas.draw_idle()
+
+
+# A class that will regenerate a fractal set as we zoom in, so that you
+# can actually see the increasing detail.  A box in the left panel will show
+# the area to which we are zoomed.
+class MandelbrotDisplay(object):
+    def __init__(self, h=500, w=500, niter=50, radius=2., power=2):
+        self.height = h
+        self.width = w
+        self.niter = niter
+        self.radius = radius
+        self.power = power
+
+    def __call__(self, xstart, xend, ystart, yend):
+        self.x = np.linspace(xstart, xend, self.width)
+        self.y = np.linspace(ystart, yend, self.height).reshape(-1, 1)
+        c = self.x + 1.0j * self.y
+        threshold_time = np.zeros((self.height, self.width))
+        z = np.zeros(threshold_time.shape, dtype=complex)
+        mask = np.ones(threshold_time.shape, dtype=bool)
+        for i in range(self.niter):
+            z[mask] = z[mask]**self.power + c[mask]
+            mask = (np.abs(z) < self.radius)
+            threshold_time += mask
+        return threshold_time
+
+    def ax_update(self, ax):
+        ax.set_autoscale_on(False)  # Otherwise, infinite loop
+
+        # Get the number of points from the number of pixels in the window
+        dims = ax.patch.get_window_extent().bounds
+        self.width = int(dims[2] + 0.5)
+        self.height = int(dims[2] + 0.5)
+
+        # Get the range for the new area
+        xstart, ystart, xdelta, ydelta = ax.viewLim.bounds
+        xend = xstart + xdelta
+        yend = ystart + ydelta
+
+        # Update the image object with our new data and extent
+        im = ax.images[-1]
+        im.set_data(self.__call__(xstart, xend, ystart, yend))
+        im.set_extent((xstart, xend, ystart, yend))
+        ax.figure.canvas.draw_idle()
+
+md = MandelbrotDisplay()
+Z = md(-2., 0.5, -1.25, 1.25)
+
+fig1, (ax1, ax2) = plt.subplots(1, 2)
+ax1.imshow(Z, origin='lower', extent=(md.x.min(), md.x.max(), md.y.min(), md.y.max()))
+ax2.imshow(Z, origin='lower', extent=(md.x.min(), md.x.max(), md.y.min(), md.y.max()))
+
+rect = UpdatingRect([0, 0], 0, 0, facecolor='None', edgecolor='black', linewidth=1.0)
+rect.set_bounds(*ax2.viewLim.bounds)
+ax1.add_patch(rect)
+
+# Connect for changing the view limits
+ax2.callbacks.connect('xlim_changed', rect)
+ax2.callbacks.connect('ylim_changed', rect)
+
+ax2.callbacks.connect('xlim_changed', md.ax_update)
+ax2.callbacks.connect('ylim_changed', md.ax_update)
+ax2.set_title("Zoom here")
+
+plt.show()
+```
+
+## 下载这个示例
+            
+- [下载python源码: viewlims.py](https://matplotlib.org/_downloads/viewlims.py)
+- [下载Jupyter notebook: viewlims.ipynb](https://matplotlib.org/_downloads/viewlims.ipynb)