Iteration problem with plot_date

H?ctor> savefig("c:\\tmp\\%s_%s" % (tel,table)) File
    H?ctor> "C:\Python23\Lib\site-packages\matplotlib\", line
    H?ctor> 1115, in savefig manager.canvas.print_figure(*args,
    H?ctor> **kwargs) File
    H?ctor> "C:\Python23\Lib\site-packages\matplotlib\backends\",
    H?ctor> line 419, in print_figure
    H?ctor> self.renderer._renderer.write_png(filename) IOError: could
    H?ctor> not open file

This is a new one; I think the file is not writable and it is not a
matplotlib problem per se. Is it possible that C:\\tmp does not

You may want to try something along the lines of

import os

dirname = 'c:\\tmp'
fname = os.path.join(dirname, '%s_%s' % (tel,table))
print 'dir exists', os.path.exists(dirname)
print 'filename', fname

file(fname, 'w').write('test\n')

and see if you can see what is going wrong.