APE6 example does not round trip

[pllim]

I am trying out an example on APE 6 but I cannot get it to round trip on write/read with Python 3.7.1, Astropy 3.1, and Numpy 1.15.4. I am not sure if there is a policy to ensure APE examples always work, but I am reporting this anyway FWIW.

>>> from astropy.table import Table
>>> from collections import OrderedDict
>>> import astropy.units as u
>>> t = Table([[1, 4], [2, 3]], names=['a', 'b'])
>>> t.meta['keywords'] = OrderedDict([('z_key1', 'val1'), ('a_key2', 'val2')])
>>> t.meta['comments'] = ['Comment 1', 'Comment 2', 'Comment 3']
>>> t['a'].unit = u.m / u.s
>>> t['a'].format = '%5.2f'
>>> t['a'].description = 'Column A'
>>> t['b'].meta = dict(column_meta={'a':1, 'b': 2})
>>> In [13]: t
<Table length=2>
  a     b
m / s
int32 int32
----- -----
 1.00     2
 4.00     3
>>> t.meta
OrderedDict([('keywords',
              OrderedDict([('z_key1', 'val1'), ('a_key2', 'val2')])),
             ('comments', ['Comment 1', 'Comment 2', 'Comment 3'])])
>>> t.write('ztmp.ecsv')
>>> t2 = Table.read('ztmp.ecsv')
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
...\astropy\io\ascii\core.py in _convert_va
ls(self, cols)
    952                 try:
--> 953                     converter_func, converter_type = col.converters[0]
    954                     if not issubclass(converter_type, col.type):

IndexError: list index out of range

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
<ipython-input-15-eb21516157bd> in <module>
----> 1 t2 = Table.read('ztmp.ecsv')

...\astropy\table\table.py in read(cls, *ar
gs, **kwargs)
   2546         # RST table and inserts at the end of the docstring.  DO NOT REM
OVE.
   2547
-> 2548         out = io_registry.read(cls, *args, **kwargs)
   2549         # For some readers (e.g., ascii.ecsv), the returned `out` class
is not
   2550         # guaranteed to be the same as the desired output `cls`.  If so,


...\astropy\io\registry.py in read(cls, for
mat, *args, **kwargs)
    515
    516         reader = get_reader(format, cls)
--> 517         data = reader(*args, **kwargs)
    518
    519         if not isinstance(data, cls):

...\astropy\io\ascii\connect.py in io_read(
format, filename, **kwargs)
     35     from .ui import read
     36     format = re.sub(r'^ascii\.', '', format)
---> 37     return read(filename, format=format, **kwargs)
     38
     39

...\astropy\io\ascii\ui.py in read(table, g
uess, **kwargs)
    402         else:
    403             reader = get_reader(**new_kwargs)
--> 404             dat = reader.read(table)
    405             _read_trace.append({'kwargs': copy.deepcopy(new_kwargs),
    406                                 'Reader': reader.__class__,

...\astropy\io\ascii\core.py in read(self,
table)
   1195         if hasattr(self.header, 'table_meta'):
   1196             self.meta['table'].update(self.header.table_meta)
-> 1197         table = self.outputter(cols, self.meta)
   1198         self.cols = self.header.cols
   1199

...\astropy\io\ascii\ecsv.py in __call__(se
lf, cols, meta)
    190     def __call__(self, cols, meta):
    191         # Convert to a Table with all plain Column subclass columns
--> 192         out = super().__call__(cols, meta)
    193
    194         # If mixin columns exist (based on the special '__mixin_columns_
_'

...\astropy\io\ascii\core.py in __call__(se
lf, cols, meta)
    982         # Sets col.data to numpy array and col.type to io.ascii Type cla
ss (e.g.
    983         # FloatType) for each col.
--> 984         self._convert_vals(cols)
    985
    986         # If there are any values that were filled and tagged with a mas
k bit then this

...\astropy\io\ascii\core.py in _convert_va
ls(self, cols)
    967                     last_err = err
    968                 except IndexError:
--> 969                     raise ValueError('Column {} failed to convert: {}'.f
ormat(col.name, last_err))
    970
    971

ValueError: Column a failed to convert: invalid literal for int() with base 10:
'1.00'

[taldcroft]

Why oh why did I make such a weird example? Setting an int to have a %5.2 format is just silly, but of course Python2 was "helpful" and let that not break on roundtrip. The following is a fix:

>>> t = Table([[1.0, 4.0], [2, 3]], names=['a', 'b'])

But the bigger question of testing APE6 examples is quite good.