[AstroPy] How can I create a VOtable from a python list?

Michael Droettboom mdroe@stsci....
Wed Mar 6 08:08:41 CST 2013


The general approach you're taking here -- to create a Table and then 
convert it to a VOTable -- is the right one here.  The Table class has a 
much richer set of things it can convert to and from (it's sort of our 
"hub" class for everything that's table like).

However, I don't believe it supports construction from a list in the way 
you're trying.  There is a doc page about constructing a table here, 
that may be helpful:

https://astropy.readthedocs.org/en/v0.2/table/construct_table.html

That said, I tried to convert your example to the form where the Table 
is constructed from a Numpy structured array, and still ran into the 
same exception:

from astropy import table

from astropy.io import votable

import numpy as np

x = np.array(

     [("CIG12",1.2345,0,2,999,"COMMENT"),

      ("CIG122",1.23452,0,2,9992,"COMMENT2")],

     dtype=[('a', str), ('b', float), ('c', int), ('d', int), ('e', int), ('f', str)])

print x.dtype

t = table.Table(x)

votable = votable.tree.VOTableFile.from_table(t)


So maybe we're both still doing something wrong.  I've Cc'd Tom 
Aldcroft, the primary author of the Table class, as he might have more 
insight.

Mike


On 03/04/2013 06:43 AM, Susana Sanchez wrote:
> Hello all,
>
> How can I create a VOtable from a list (a python list) of rows using astropy?
>
> Reading the documentation, I found the method "from_table" of the
> class VOTableFile, this method needs as argument an instance of the
> class astropy.table.table.Table, so I did the following:
>
> t=astropy.table.table.Table([["CIG12",1.2345,0,2,999,"COMMENT"],["CIG122",1.23452,0,2,9992,"COMMENT2"]])
> votable = VOTableFile()
> votable.from_table(t)
>
>
> But here I got this error:
>
> /usr/local/lib/python2.6/dist-packages/numpy/ma/core.pyc in
> __new__(cls, data, mask, dtype, copy, subok, ndmin, fill_value,
> keep_mask, hard_mask, shrink, **options)
>     2692             # Or assume it's a sequence of bool/int
>
>     2693             except TypeError:
> -> 2694                 mask = np.array([tuple([m] * len(mdtype)) for
> m in mask],
>     2695                                  dtype=mdtype)
>     2696             # Make sure the mask and the data have the same shape
>
> TypeError: 'NoneType' object is not iterable
>
>
> Reading the error message,  I thought it could be related with the
> mask, so I tried to create the mask of the table t (with the method
> t.create_mask()), and then to build the VOTableFile from this table,
> but I got the same error.
>
> I would be very gratefully, If anyone can help me or give me any hint.
>
> Thanks,
> Susana.
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