cannot open more than one figure with wcs

[astrofrog]

Every time I try to open a second figure, I get this:

IPython 2.2.0 -- An enhanced Interactive Python.
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?         -> Introduction and overview of IPython's features.       
%quickref -> Quick reference.                                       
help      -> Python's own help system.                              
object?   -> Details about 'object', use 'object??' for extra details.
Using matplotlib backend: Qt4Agg                                      

In [1]: from wcsaxes import datasets, WCS

In [2]: 

In [2]: hdu = datasets.fetch_msx_hdu()
WARNING: VerifyWarning: Invalid 'BLANK' keyword in header.  The 'BLANK' keyword is only applicable to integer data, and will be ignored in this HDU. [astropy.io.fits.hdu.image]                          

In [3]: wcs = WCS(hdu.header)

In [4]: import matplotlib.pyplot as plt

In [5]: fig = plt.figure()

In [6]: ax = fig.add_axes([0.15, 0.1, 0.8, 0.8], projection=wcs)

In [7]: fig2 = plt.figure()

In [8]: ax2 = fig2.add_axes([0.15, 0.1, 0.8, 0.8], projection=wcs)

In [9]: Traceback (most recent call last):
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backends/backend_qt5.py", line 282, in mouseMoveEvent                                                                    
    FigureCanvasBase.motion_notify_event(self, x, y)                                                 
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 1917, in motion_notify_event                                                                     
    self.callbacks.process(s, event)                                                                 
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.py", line 533, in process                                                                                          
    proxy(*args, **kwargs)                                                                           
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.py", line 408, in __call__                                                                                         
    return mtd(*args, **kwargs)                                                                      
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 2761, in mouse_move                                                                              
    s = event.inaxes.format_coord(event.xdata, event.ydata)                                          
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/core.py", line 61, in _display_world_coords                                                    
    xw = coords[self._x_index].format_coord(world[self._x_index])                                    
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/coordinate_helpers.py", line 183, in format_coord                                              
    spacing = self._fl_spacing                                                                       
AttributeError: 'CoordinateHelper' object has no attribute '_fl_spacing'                             

If you suspect this is an IPython bug, please report it at:
    https://github.com/ipython/ipython/issues              
or send an email to the mailing list at ipython-dev@scipy.org

You can print a more detailed traceback right now with "%tb", or use "%debug"
to interactively debug it.                                                   

Extra-detailed tracebacks for bug-reporting purposes can be enabled via:
    %config Application.verbose_crash=True                              

Traceback (most recent call last):
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backends/backend_qt5.py", line 282, in mouseMoveEvent                                                                    
    FigureCanvasBase.motion_notify_event(self, x, y)                                                 
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 1917, in motion_notify_event                                                                     
    self.callbacks.process(s, event)                                                                 
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.py", line 533, in process                                                                                          
    proxy(*args, **kwargs)                                                                           
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.py", line 408, in __call__                                                                                         
    return mtd(*args, **kwargs)                                                                      
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 2761, in mouse_move                                                                              
    s = event.inaxes.format_coord(event.xdata, event.ydata)                                          
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/core.py", line 61, in _display_world_coords                                                    
    xw = coords[self._x_index].format_coord(world[self._x_index])                                    
  File "/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/coordinate_helpers.py", line 183, in format_coord                                              
    spacing = self._fl_spacing                                                                       
AttributeError: 'CoordinateHelper' object has no attribute '_fl_spacing'                             

If you suspect this is an IPython bug, please report it at:
    https://github.com/ipython/ipython/issues              
or send an email to the mailing list at ipython-dev@scipy.org

You can print a more detailed traceback right now with "%tb", or use "%debug"
to interactively debug it.

Extra-detailed tracebacks for bug-reporting purposes can be enabled via:
    %config Application.verbose_crash=True

%tb
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.pyc in motion_notify_event(self, x, y, guiEvent)
   1915         event = MouseEvent(s, self, x, y, self._button, self._key,
   1916                            guiEvent=guiEvent)
-> 1917         self.callbacks.process(s, event)
   1918
   1919     def leave_notify_event(self, guiEvent=None):

/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.pyc in process(self, s, *args, **kwargs)
    531                     del self.callbacks[s][cid]
    532                 else:
--> 533                     proxy(*args, **kwargs)
    534
    535

/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/cbook.pyc in __call__(self, *args, **kwargs)
    406             mtd = self.func
    407         # invoke the callable and return the result
--> 408         return mtd(*args, **kwargs)
    409
    410     def __eq__(self, other):

/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/matplotlib/backend_bases.pyc in mouse_move(self, event)
   2759
   2760             try:
-> 2761                 s = event.inaxes.format_coord(event.xdata, event.ydata)
   2762             except (ValueError, OverflowError):
   2763                 pass

/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/core.pyc in _display_world_coords(self, x, y)
     59         world = coords._transform.transform(np.array([pixel]))[0]
     60
---> 61         xw = coords[self._x_index].format_coord(world[self._x_index])
     62         yw = coords[self._y_index].format_coord(world[self._y_index])
     63

/melkor/d1/guenther/soft/anaconda/lib/python2.7/site-packages/wcsaxes-0.4.dev506-py2.7.egg/wcsaxes/coordinate_helpers.pyc in format_coord(self, value)
    181             value = value * u.degree
    182             value = value.to(fl._unit).value
--> 183         spacing = self._fl_spacing
    184         string = fl.formatter(values=[value] * fl._unit, spacing=spacing)
    185         return string[0]

AttributeError: 'CoordinateHelper' object has no attribute '_fl_spacing'

[astrofrog]

Huh, weird! Will investigate :)

[astrofrog]

Ok this is a bug that occurs because with the Qt backend, it calls format_coord before the axes have been drawn the first time (to show the 'hover-over coords'). Working on a solution.