In [4]: from astropy.table import Table

In [5]: t = Table()

In [6]: t['a'] = ['a','b','c']

In [7]: t['a'].format = "%9.5f"

In [8]: print(t)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-8-d6c4f5caf31e> in <module>()
----> 1 print(t)

/Volumes/Raptor/Library/Python/3.4/lib/python/site-packages/astropy-1.0.dev9579-py3.4-macosx-10.8-x86_64.egg/astropy/table/table.py in __unicode__(self)
    664 
    665     def __unicode__(self):
--> 666         lines, n_header = self.formatter._pformat_table(self)
    667         return '\n'.join(lines)
    668     if six.PY3:

/Volumes/Raptor/Library/Python/3.4/lib/python/site-packages/astropy-1.0.dev9579-py3.4-macosx-10.8-x86_64.egg/astropy/table/pprint.py in _pformat_table(self, table, max_lines, max_width, show_name, show_unit, html, tableid)
    296         for col in six.itervalues(table.columns):
    297             lines, n_header = self._pformat_col(col, max_lines, show_name,
--> 298                                                 show_unit)
    299             cols.append(lines)
    300 

/Volumes/Raptor/Library/Python/3.4/lib/python/site-packages/astropy-1.0.dev9579-py3.4-macosx-10.8-x86_64.egg/astropy/table/pprint.py in _pformat_col(self, col, max_lines, show_name, show_unit)
    148         """
    149         outs = {}  # Some values from _pformat_col_iter iterator that are needed here
--> 150         col_strs = list(self._pformat_col_iter(col, max_lines, show_name, show_unit, outs))
    151         col_width = max(len(x) for x in col_strs)
    152 

/Volumes/Raptor/Library/Python/3.4/lib/python/site-packages/astropy-1.0.dev9579-py3.4-macosx-10.8-x86_64.egg/astropy/table/pprint.py in _pformat_col_iter(self, col, max_lines, show_name, show_unit, outs)
    239                                   format_func(col.format, col[(i,) + multidim1]))
    240                 else:
--> 241                     col_str = format_func(col.format, col[i])
    242                 yield col_str
    243             elif i == i0:

/Volumes/Raptor/Library/Python/3.4/lib/python/site-packages/astropy-1.0.dev9579-py3.4-macosx-10.8-x86_64.egg/astropy/table/pprint.py in _auto_format_func(format_, val)
     62             except:
     63                 raise ValueError('Unable to parse format string {0}'
---> 64                                  .format(format_))
     65     _format_funcs[format_] = format_func
     66     return out

ValueError: Unable to parse format string %9.5f

In [9]: "%9.5f" % 'a'
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-9-55c5d51877aa> in <module>()
----> 1 "%9.5f" % 'a'

TypeError: a float is required