nan causes segfaults in merc projection

还没有人认领这个 Issue。

Moving issue from matplotlib https://github.com/matplotlib/matplotlib/issues/5991

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@mnky9800n commented 12 hours ago

When passing a value when creating the Basemap object, if that value is a numpy.nan then python 2.x crashes on windows.

This example code crashes in an ipython 2.7 notebook.

minlat = np.nan
maxlat = np.nan
minlon = np.nan
maxlon = np.nan
m = Basemap(projection='merc'
, llcrnrlat=minlat
, urcrnrlat=maxlat
, llcrnrlon=minlon
, urcrnrlon=maxlon)
I think the expected behavior would be a ValueError or something like that so that it is easier to debug. Instead of a message like this:

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You get that windows message because python is segfaulting. If executed in
the terminal, you get the following:

```
ben@tigger:~$ python
Python 2.7.10 |Continuum Analytics, Inc.| (default, May 28 2015, 17:02:03)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://binstar.org
>> import numpy as np
>> from mpl_toolkits.basemap import Basemap
>> minlat = np.nan
>> maxlat = np.nan
>> minlon = np.nan
>> maxlon = np.nan
>> m = Basemap(projection='merc'
... , llcrnrlat=minlat
... , urcrnrlat=maxlat
... , llcrnrlon=minlon
... , urcrnrlon=maxlon)
GEOS_ERROR: IllegalArgumentException: Points of LinearRing do not form a
closed linestring
Segmentation fault (core dumped)
```

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Possibly closed by #261

首先按照 issue 中的示例，使用 Mercator 投影以及四个边界均为 NaN 的值运行 Basemap 构造函数。跟踪这些投影参数的验证路径，并使最终行为明确抛出 ValueError，而不是 Python 崩溃或 segmentation fault。

由索引模型根据 Issue 内容生成。