matplotlib & pandas

Python/matplotlab/gallery/shapes_and_collections/collections.md

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+# 具有自动缩放功能的Line，Poly和RegularPoly Collection
+
+对于前两个子图，我们将使用螺旋。它们的大小将以图表单位设置，而不是数据单位。它们的位置将通过使用LineCollection和PolyCollection的“偏移”和“transOffset”kwargs以数据单位设置。
+
+第三个子图将生成正多边形，具有与前两个相同类型的缩放和定位。
+
+最后一个子图说明了使用 “offsets =（xo，yo）”，即单个元组而不是元组列表来生成连续的偏移曲线，其中偏移量以数据单位给出。 此行为仅适用于LineCollection。
+
+```python
+import matplotlib.pyplot as plt
+from matplotlib import collections, colors, transforms
+import numpy as np
+
+nverts = 50
+npts = 100
+
+# Make some spirals
+r = np.arange(nverts)
+theta = np.linspace(0, 2*np.pi, nverts)
+xx = r * np.sin(theta)
+yy = r * np.cos(theta)
+spiral = np.column_stack([xx, yy])
+
+# Fixing random state for reproducibility
+rs = np.random.RandomState(19680801)
+
+# Make some offsets
+xyo = rs.randn(npts, 2)
+
+# Make a list of colors cycling through the default series.
+colors = [colors.to_rgba(c)
+          for c in plt.rcParams['axes.prop_cycle'].by_key()['color']]
+
+fig, axes = plt.subplots(2, 2)
+fig.subplots_adjust(top=0.92, left=0.07, right=0.97,
+                    hspace=0.3, wspace=0.3)
+((ax1, ax2), (ax3, ax4)) = axes  # unpack the axes
+
+
+col = collections.LineCollection([spiral], offsets=xyo,
+                                 transOffset=ax1.transData)
+trans = fig.dpi_scale_trans + transforms.Affine2D().scale(1.0/72.0)
+col.set_transform(trans)  # the points to pixels transform
+# Note: the first argument to the collection initializer
+# must be a list of sequences of x,y tuples; we have only
+# one sequence, but we still have to put it in a list.
+ax1.add_collection(col, autolim=True)
+# autolim=True enables autoscaling.  For collections with
+# offsets like this, it is neither efficient nor accurate,
+# but it is good enough to generate a plot that you can use
+# as a starting point.  If you know beforehand the range of
+# x and y that you want to show, it is better to set them
+# explicitly, leave out the autolim kwarg (or set it to False),
+# and omit the 'ax1.autoscale_view()' call below.
+
+# Make a transform for the line segments such that their size is
+# given in points:
+col.set_color(colors)
+
+ax1.autoscale_view()  # See comment above, after ax1.add_collection.
+ax1.set_title('LineCollection using offsets')
+
+
+# The same data as above, but fill the curves.
+col = collections.PolyCollection([spiral], offsets=xyo,
+                                 transOffset=ax2.transData)
+trans = transforms.Affine2D().scale(fig.dpi/72.0)
+col.set_transform(trans)  # the points to pixels transform
+ax2.add_collection(col, autolim=True)
+col.set_color(colors)
+
+
+ax2.autoscale_view()
+ax2.set_title('PolyCollection using offsets')
+
+# 7-sided regular polygons
+
+col = collections.RegularPolyCollection(
+    7, sizes=np.abs(xx) * 10.0, offsets=xyo, transOffset=ax3.transData)
+trans = transforms.Affine2D().scale(fig.dpi / 72.0)
+col.set_transform(trans)  # the points to pixels transform
+ax3.add_collection(col, autolim=True)
+col.set_color(colors)
+ax3.autoscale_view()
+ax3.set_title('RegularPolyCollection using offsets')
+
+
+# Simulate a series of ocean current profiles, successively
+# offset by 0.1 m/s so that they form what is sometimes called
+# a "waterfall" plot or a "stagger" plot.
+
+nverts = 60
+ncurves = 20
+offs = (0.1, 0.0)
+
+yy = np.linspace(0, 2*np.pi, nverts)
+ym = np.max(yy)
+xx = (0.2 + (ym - yy) / ym) ** 2 * np.cos(yy - 0.4) * 0.5
+segs = []
+for i in range(ncurves):
+    xxx = xx + 0.02*rs.randn(nverts)
+    curve = np.column_stack([xxx, yy * 100])
+    segs.append(curve)
+
+col = collections.LineCollection(segs, offsets=offs)
+ax4.add_collection(col, autolim=True)
+col.set_color(colors)
+ax4.autoscale_view()
+ax4.set_title('Successive data offsets')
+ax4.set_xlabel('Zonal velocity component (m/s)')
+ax4.set_ylabel('Depth (m)')
+# Reverse the y-axis so depth increases downward
+ax4.set_ylim(ax4.get_ylim()[::-1])
+
+
+plt.show()
+```
+
+![缩放功能示例](https://matplotlib.org/_images/sphx_glr_collections_001.png)
+
+## 参考
+
+此示例中显示了以下函数，方法，类和模块的使用：
+
+```python
+import matplotlib
+matplotlib.figure.Figure
+matplotlib.collections
+matplotlib.collections.LineCollection
+matplotlib.collections.RegularPolyCollection
+matplotlib.axes.Axes.add_collection
+matplotlib.axes.Axes.autoscale_view
+matplotlib.transforms.Affine2D
+matplotlib.transforms.Affine2D.scale
+```
+
+## 下载这个示例
+            
+- [下载python源码: collections.py](https://matplotlib.org/_downloads/collections.py)
+- [下载Jupyter notebook: collections.ipynb](https://matplotlib.org/_downloads/collections.ipynb)