CEA projection: plotting all the data works, plotting part of the data fails.

Using the following setup, Python 2.7/matplotlib 1.2.1/basemap 1.0.6

from mpl_toolkits import basemap

m1 = basemap.Basemap(projection='cea', lon_0=0)
lon = [-135, -45, 45, 135]
lat = [45, 45, 45, 45]

If I then run the following command, the line plots as expected:

m1.plot(lon, lat, latlon=True)

But plotting just the first two points alone gives a failure:

m1.plot(lon[:2], lat[:2], latlon=True)

Here's the result:

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-273-c6f75eb64ab8> in <module>()
      8 lat = [45, 45, 45, 45]
      9 #m1.plot(lon, lat, latlon=True)
---> 10 m1.plot(lon[:2], lat[:2], latlon=True)

/Users/jakevdp/anaconda/python.app/Contents/lib/python2.7/site-packages/mpl_toolkits/basemap/__init__.pyc in with_transform(self, x, y, *args, **kwargs)
    525             if self.projection in _cylproj or self.projection in _pseudocyl:
    526                 if x.ndim == 1:
--> 527                     x = self.shiftdata(x)
    528                 elif x.ndim == 0:
    529                     if x > 180:

/Users/jakevdp/anaconda/python.app/Contents/lib/python2.7/site-packages/mpl_toolkits/basemap/__init__.pyc in shiftdata(self, lonsin, datain, lon_0)
   4700             londiff = np.abs(lonsin[0:-1]-lonsin[1:])
   4701             londiff_sort = np.sort(londiff)
-> 4702             thresh = 360.-londiff_sort[-2]
   4703             itemindex = len(lonsin)-np.where(londiff>=thresh)[0]
   4704             if itemindex:

IndexError: index -2 is out of bounds for axis 0 with size 1

Edit: here's an error from a similar call, but I believe it's unrelated to the first:

lat = [-45, 45, 45, 45, 45, 0]
lon = [135, -135, -45, 45, 135, -90]
m1.plot(lon, lat, latlon=True)

error:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-295-d815d338a0b6> in <module>()
     11 lon = [135, -135, -45, 45, 135, -90]
     12 
---> 13 m1.plot(lon, lat, latlon=True)
     14 

/Users/jakevdp/anaconda/python.app/Contents/lib/python2.7/site-packages/mpl_toolkits/basemap/__init__.pyc in with_transform(self, x, y, *args, **kwargs)
    525             if self.projection in _cylproj or self.projection in _pseudocyl:
    526                 if x.ndim == 1:
--> 527                     x = self.shiftdata(x)
    528                 elif x.ndim == 0:
    529                     if x > 180:

/Users/jakevdp/anaconda/python.app/Contents/lib/python2.7/site-packages/mpl_toolkits/basemap/__init__.pyc in shiftdata(self, lonsin, datain, lon_0)
   4702             thresh = 360.-londiff_sort[-2]
   4703             itemindex = len(lonsin)-np.where(londiff>=thresh)[0]
-> 4704             if itemindex:
   4705                 # check to see if cyclic (wraparound) point included
   4706                 # if so, remove it.

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Tái hiện hai ví dụ với thiết lập Python 2.7, matplotlib 1.2.1 và Basemap 1.0.6, sau đó kiểm tra mpl_toolkits/basemap/init.py xung quanh các điểm đầu vào m1.plot transform và shiftdata được hiển thị trong traceback. Hoàn tất khi việc vẽ tập con gồm hai điểm thành công và ví dụ liên quan với nhiều điểm không còn phát sinh các lỗi lập chỉ mục hoặc giá trị boolean đã báo cáo.