python - matplotlib 等高线图； 'module' 对象没有属性 'nextafter'

Question

尝试重现 this question 中的问题，我发现我什至无法绘制最简单的等高线图。

这是来自 gallery 的(hopefelly)相关示例的简化版本

#!/usr/bin/env python
import matplotlib
import numpy as np
import matplotlib.cm as cm
import matplotlib.mlab as mlab
import matplotlib.pyplot as plt

delta = 0.025
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-2.0, 2.0, delta)
X, Y = np.meshgrid(x, y)
#Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)   
#Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
# difference of Gaussians
Z = 10.0 * np.exp(X-Y)  #(Z2 - Z1)

plt.figure()
CS = plt.contour(X,Y,Z)

plt.show()

这给了我这个:

Traceback (most recent call last):
  File "./contour.py", line 19, in <module>
    CS = plt.contour(X,Y,Z)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/pyplot.py", line 2188, in contour
    ret = ax.contour(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/axes.py", line 7316, in contour
    return mcontour.QuadContourSet(self, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/contour.py", line 1106, in __init__
    ContourSet.__init__(self, ax, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/contour.py", line 720, in __init__
    self._process_colors()
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/contour.py", line 954, in _process_colors
    self.set_clim(self.vmin, self.vmax)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/cm.py", line 248, in set_clim
    self.changed()
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/contour.py", line 841, in changed
    self.to_rgba(self.cvalues, alpha=self.alpha)]
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/cm.py", line 214, in to_rgba
    x = self.cmap(x, alpha=alpha, bytes=bytes)
  File "/usr/local/lib/python2.6/dist-packages/matplotlib/colors.py", line 520, in __call__
    cbook._putmask(xa, xa==1.0, np.nextafter(xa.dtype.type(1),
AttributeError: 'module' object has no attribute 'nextafter'

这些错误并不取决于我是否坚持原始的“高斯差异”或尝试仅绘制指数，如上面的代码片段所示。

我错过了一些微不足道的事情吗？

如果相关的话，我在 Ubuntu 10.04 上使用 matplotlib 1.1.0

Answer 1

不，你没有做错任何事。您需要升级 Numpy。我遇到了同样的问题，更新到 Numpy 1.6.1 后，一切顺利。

使用 Lucid Lynx (Ubuntu 10.04)，您可以访问 numpy 1.3.0 。缺少的 nextafter 函数仅在 numpy 1.4 之后可用。 (感谢DSM)。