matplotlib等高线图; '模块'对象没有属性'nextafter'

Question

试图从this question重现问题，我发现我不能绘制一个最简单的轮廓图。

下面是从gallery

#!/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() 

，给了我一个（hopefelly）相关的实例的简化版本：

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' 

的误差并不取决于我是否坚持原来的'高斯差异'或者尝试绘制一个指数，就像上面的代码片断一样。

我是否错过了一些微不足道的东西？

如果它是相关的，我在Ubuntu 10.04

Answer 1

使用matplotlib 1.1.0没有你没有做错什么。你需要升级Numpy。我遇到了同样的问题，在对Numpy 1.6.1进行更新后，事情进展顺利。

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