matplotlib & pandas

Python/matplotlab/gallery/axisartist/demo_floating_axes.md

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+# 演示浮动轴
+
+浮动轴的演示。
+
+```python
+from matplotlib.transforms import Affine2D
+import mpl_toolkits.axisartist.floating_axes as floating_axes
+import numpy as np
+import mpl_toolkits.axisartist.angle_helper as angle_helper
+from matplotlib.projections import PolarAxes
+from mpl_toolkits.axisartist.grid_finder import (FixedLocator, MaxNLocator,
+                                                 DictFormatter)
+import matplotlib.pyplot as plt
+
+# Fixing random state for reproducibility
+np.random.seed(19680801)
+
+
+def setup_axes1(fig, rect):
+    """
+    A simple one.
+    """
+    tr = Affine2D().scale(2, 1).rotate_deg(30)
+
+    grid_helper = floating_axes.GridHelperCurveLinear(
+        tr, extremes=(-0.5, 3.5, 0, 4))
+
+    ax1 = floating_axes.FloatingSubplot(fig, rect, grid_helper=grid_helper)
+    fig.add_subplot(ax1)
+
+    aux_ax = ax1.get_aux_axes(tr)
+
+    grid_helper.grid_finder.grid_locator1._nbins = 4
+    grid_helper.grid_finder.grid_locator2._nbins = 4
+
+    return ax1, aux_ax
+
+
+def setup_axes2(fig, rect):
+    """
+    With custom locator and formatter.
+    Note that the extreme values are swapped.
+    """
+    tr = PolarAxes.PolarTransform()
+
+    pi = np.pi
+    angle_ticks = [(0, r"$0$"),
+                   (.25*pi, r"$\frac{1}{4}\pi$"),
+                   (.5*pi, r"$\frac{1}{2}\pi$")]
+    grid_locator1 = FixedLocator([v for v, s in angle_ticks])
+    tick_formatter1 = DictFormatter(dict(angle_ticks))
+
+    grid_locator2 = MaxNLocator(2)
+
+    grid_helper = floating_axes.GridHelperCurveLinear(
+        tr, extremes=(.5*pi, 0, 2, 1),
+        grid_locator1=grid_locator1,
+        grid_locator2=grid_locator2,
+        tick_formatter1=tick_formatter1,
+        tick_formatter2=None)
+
+    ax1 = floating_axes.FloatingSubplot(fig, rect, grid_helper=grid_helper)
+    fig.add_subplot(ax1)
+
+    # create a parasite axes whose transData in RA, cz
+    aux_ax = ax1.get_aux_axes(tr)
+
+    aux_ax.patch = ax1.patch  # for aux_ax to have a clip path as in ax
+    ax1.patch.zorder = 0.9  # but this has a side effect that the patch is
+    # drawn twice, and possibly over some other
+    # artists. So, we decrease the zorder a bit to
+    # prevent this.
+
+    return ax1, aux_ax
+
+
+def setup_axes3(fig, rect):
+    """
+    Sometimes, things like axis_direction need to be adjusted.
+    """
+
+    # rotate a bit for better orientation
+    tr_rotate = Affine2D().translate(-95, 0)
+
+    # scale degree to radians
+    tr_scale = Affine2D().scale(np.pi/180., 1.)
+
+    tr = tr_rotate + tr_scale + PolarAxes.PolarTransform()
+
+    grid_locator1 = angle_helper.LocatorHMS(4)
+    tick_formatter1 = angle_helper.FormatterHMS()
+
+    grid_locator2 = MaxNLocator(3)
+
+    # Specify theta limits in degrees
+    ra0, ra1 = 8.*15, 14.*15
+    # Specify radial limits
+    cz0, cz1 = 0, 14000
+    grid_helper = floating_axes.GridHelperCurveLinear(
+        tr, extremes=(ra0, ra1, cz0, cz1),
+        grid_locator1=grid_locator1,
+        grid_locator2=grid_locator2,
+        tick_formatter1=tick_formatter1,
+        tick_formatter2=None)
+
+    ax1 = floating_axes.FloatingSubplot(fig, rect, grid_helper=grid_helper)
+    fig.add_subplot(ax1)
+
+    # adjust axis
+    ax1.axis["left"].set_axis_direction("bottom")
+    ax1.axis["right"].set_axis_direction("top")
+
+    ax1.axis["bottom"].set_visible(False)
+    ax1.axis["top"].set_axis_direction("bottom")
+    ax1.axis["top"].toggle(ticklabels=True, label=True)
+    ax1.axis["top"].major_ticklabels.set_axis_direction("top")
+    ax1.axis["top"].label.set_axis_direction("top")
+
+    ax1.axis["left"].label.set_text(r"cz [km$^{-1}$]")
+    ax1.axis["top"].label.set_text(r"$\alpha_{1950}$")
+
+    # create a parasite axes whose transData in RA, cz
+    aux_ax = ax1.get_aux_axes(tr)
+
+    aux_ax.patch = ax1.patch  # for aux_ax to have a clip path as in ax
+    ax1.patch.zorder = 0.9  # but this has a side effect that the patch is
+    # drawn twice, and possibly over some other
+    # artists. So, we decrease the zorder a bit to
+    # prevent this.
+
+    return ax1, aux_ax
+```
+
+```python
+fig = plt.figure(1, figsize=(8, 4))
+fig.subplots_adjust(wspace=0.3, left=0.05, right=0.95)
+
+ax1, aux_ax1 = setup_axes1(fig, 131)
+aux_ax1.bar([0, 1, 2, 3], [3, 2, 1, 3])
+
+ax2, aux_ax2 = setup_axes2(fig, 132)
+theta = np.random.rand(10)*.5*np.pi
+radius = np.random.rand(10) + 1.
+aux_ax2.scatter(theta, radius)
+
+ax3, aux_ax3 = setup_axes3(fig, 133)
+
+theta = (8 + np.random.rand(10)*(14 - 8))*15.  # in degrees
+radius = np.random.rand(10)*14000.
+aux_ax3.scatter(theta, radius)
+
+plt.show()
+```
+
+![演示浮动轴](https://matplotlib.org/_images/sphx_glr_demo_floating_axes_001.png)
+
+## 下载这个示例
+            
+- [下载python源码: demo_floating_axes.py](https://matplotlib.org/_downloads/demo_floating_axes.py)
+- [下载Jupyter notebook: demo_floating_axes.ipynb](https://matplotlib.org/_downloads/demo_floating_axes.ipynb)