Question

我有时可以将start_points参数设为streamplot，但出于某种原因，我通常会收到一些我不理解的错误：

import numpy as np
import matplotlib.pyplot as plt
Y,X = np.mgrid[-10:10:.01, -10:10:.01]
U, V = Y**2, X**2
stream_points = np.array(zip(np.arange(-9,9,2), -np.arange(-9,9,2)))
plt.streamplot(X,Y, U,V, start_points=stream_points)
plt.show(False)

错误：

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
----/streamplot.py in <module>()
      4 U, V = Y**2, X**2
      5 stream_points = np.array(zip(np.arange(-9,9,2), -np.arange(-9,9,2)))
----> 6 plt.streamplot(X,Y, U,V, start_points=stream_points)
      7 plt.show(False)
      8 plt.savefig('stream.png')

/usr/lib/python2.7/dist-packages/matplotlib/pyplot.pyc in streamplot(x, y, u, v, density, linewidth, color, cmap, norm, arrowsize, arrowstyle, minlength, transform, zorder, start_points, hold, data)
   3381                             arrowsize=arrowsize, arrowstyle=arrowstyle,
   3382                             minlength=minlength, transform=transform,
-> 3383                             zorder=zorder, start_points=start_points, data=data)
   3384     finally:
   3385         ax.hold(washold)

/usr/lib/python2.7/dist-packages/matplotlib/__init__.pyc in inner(ax, *args, **kwargs)
   1812                     warnings.warn(msg % (label_namer, func.__name__),
   1813                                   RuntimeWarning, stacklevel=2)
-> 1814             return func(ax, *args, **kwargs)
   1815         pre_doc = inner.__doc__
   1816         if pre_doc is None:

/usr/lib/python2.7/dist-packages/matplotlib/axes/_axes.pyc in streamplot(self, x, y, u, v, density, linewidth, color, cmap, norm, arrowsize, arrowstyle, minlength, transform, zorder, start_points)
   4462                                               start_points=start_points,
   4463                                               transform=transform,
-> 4464                                               zorder=zorder)
   4465         return stream_container
   4466     streamplot.__doc__ = mstream.streamplot.__doc__

/usr/lib/python2.7/dist-packages/matplotlib/streamplot.pyc in streamplot(axes, x, y, u, v, density, linewidth, color, cmap, norm, arrowsize, arrowstyle, minlength, transform, zorder, start_points)
    138         # data2grid works properly.
    139         sp2 = np.asanyarray(start_points, dtype=np.float).copy()
--> 140         sp2[:, 0] += np.abs(x[0])
    141         sp2[:, 1] += np.abs(y[0])
    142         for xs, ys in sp2:

ValueError: operands could not be broadcast together with shapes (9,) (2000,) (9,)

Matplotlib streamplot start_points ValueError

0 个答案: