Problem using barbs function

David_Craig · May 10, 2012, 3:11pm

Hi,

I'm having a problem using matplotlibs barbs function. I'm trying to

plot some wind barbs on a map created with basemap. My code is as
follows,

m =
Basemap(llcrnrlon=-35.0,llcrnrlat=40.0,urcrnrlon=10.0,urcrnrlat=68.0,

resolution=‘i’,projection=‘lcc’,lon_0=-12.5,lat_0=54.0)

    m.drawcoastlines()

    m.bluemarble()

    m.drawcoastlines()

    # draw parallels

    m.drawparallels(np.arange(40,68,5),labels=[1,0,0,0])

    # draw meridians

    m.drawmeridians(np.arange(-35, 10, 5),labels=[0,0,0,1])



    x, y = m(lons, lats)

    m.barbs(lons,lats,us,vs, barbcolor = 'r', flagcolor = 'r')

    plt.show()

  </small>

where x, y, us and vs are lists with shape (64,). I get the

following error,

ERROR: An unexpected error occurred while
tokenizing input

    The following traceback may be corrupted or invalid

    The error message is: ('EOF in multi-line statement', (382, 0))

    ValueError                                Traceback (most recent

call last)

    /home/davcra/python_scripts/plot_synops.py in <module>()

         63 #m.plot(x,y,'ro', ms=5)



         64 plt.suptitle(record['date'])

    ---> 65 m.barbs(x,y,us,vs, barbcolor = 'r', flagcolor = 'r')

         66 #m.xlim(-35.0, 10.0)



         67 #m.ylim(40.0, 68.0)





    /usr/lib64/python2.6/site-packages/mpl_toolkits/basemap/__init__.pyc

in barbs(self, x, y, u, v, *args, **kwargs)

       2924             retnh =

ax.barbs(x,y,unh,vnh,*args,**kwargs)

       2925             kwargs['flip_barb']=True

    -> 2926             retsh =

ax.barbs(x,y,ush,vsh,*args,**kwargs)

       2927             try:

       2928                 plt.draw_if_interactive()



    /usr/lib64/python2.6/site-packages/matplotlib/axes.pyc in

barbs(self, *args, **kw)

       5888         """

       5889         if not self._hold: self.cla()

    -> 5890         b = mquiver.Barbs(self, *args, **kw)

       5891         self.add_collection(b)

       5892         self.update_datalim(b.get_offsets())



    /usr/lib64/python2.6/site-packages/matplotlib/quiver.pyc in

init(self, ax, *args, **kw)

self.set_transform(transforms.IdentityTransform())

        777

    --> 778         self.set_UVC(u, v, c)

        779

        780     __init__.__doc__ = """



    /usr/lib64/python2.6/site-packages/matplotlib/quiver.pyc in

set_UVC(self, U, V, C)

        952

        953     def set_UVC(self, U, V, C=None):

    --> 954         self.u = ma.masked_invalid(U,

copy=False).ravel()

        955         self.v = ma.masked_invalid(V,

copy=False).ravel()

        956         if C is not None:



    /usr/lib64/python2.6/site-packages/numpy/ma/core.pyc in

masked_invalid(a, copy)

       1976     condition = ~(np.isfinite(a))

       1977     if hasattr(a, '_mask'):

    -> 1978         condition = mask_or(condition, a._mask)

       1979         cls = type(a)

       1980     else:



    /usr/lib64/python2.6/site-packages/numpy/ma/core.pyc in

mask_or(m1, m2, copy, shrink)

       1383         _recursive_mask_or(m1, m2, newmask)

       1384         return newmask

    -> 1385     return make_mask(umath.logical_or(m1, m2),

copy=copy, shrink=shrink)

       1386

       1387



    /usr/lib64/python2.6/site-packages/numpy/ma/core.pyc in

make_mask(m, copy, shrink, flag, dtype)

       1265         # We won't return after this point to make sure

we can shrink the mask

       1266         # Fill the mask in case there are missing data



    -> 1267         m = filled(m, True)

       1268         # Make sure the input dtype is valid



       1269         dtype = make_mask_descr(dtype)



    /usr/lib64/python2.6/site-packages/numpy/ma/core.pyc in

filled(a, fill_value)

        406     """

        407     if hasattr(a, 'filled'):

    --> 408         return a.filled(fill_value)

        409     elif isinstance(a, ndarray):

        410         # Should we check for contiguity ? and

a.flags[‘CONTIGUOUS’]:

    /usr/lib64/python2.6/site-packages/numpy/ma/core.pyc in

filled(self, fill_value)

       2929             result = self._data.copy()

       2930             try:

    -> 2931                 np.putmask(result, m, fill_value)

       2932             except (TypeError, AttributeError):

       2933                 fill_value = narray(fill_value,

dtype=object)

    ValueError: putmask: mask and data must be the same size

    WARNING: Failure executing file: <plot_synops.py>



  </small>

Anyone know whats going on here??

Thanks in advance,

D