VO tables

Note

Virtual Observatory (VO) tables are a new format developed by the International Virtual Observatory Alliance to store one or more tables. It is a format based on the Extensible Markup Language (XML).

VO tables are supported thanks to the vo module. Reading VO tables is straightforward:

>>> t = atpy.Table('table.vot')

If more than one table is present in the file, ATpy will give a list of available tables, identified by an ID (tid). The specific table to read can then be specified with the tid= argument:

>>> t = atpy.Table('table.vot', tid=2)

To read in all tables in a file, use the TableSet class:

>>> t = atpy.TableSet('table.vot')

In some cases, the VO table file may not be strictly standard compliant. When reading in a VO table, it is possible to specify an argument which controls whether to adhere strictly to standards and throw an exception if any errors are found (pedantic=True), or whether to relax the requirements and accept non-standard features (pedantic=False). The latter is the default.

Finally, when writing out a VO table, the default is to use ASCII VO tables (analogous to ASCII FITS tables). It is also possible to write tables out in binary VO format. To do this, use the votype argument:

>>> t.write('table.vot', votype='binary')

The default is votype='ascii'.

In the event that ATpy does not recognize a VO table (for example if the file extension is obscure), the type can be explicitly given:

>>> t = atpy.Table('table', type='vo')

Note

As for all file formats, the verbose argument can be specified to control whether warning messages are shown when reading (the default is verbose=True), and the overwrite argument can be used when writing to overwrite a file (the default is overwrite=False).

Full API for advanced users

Note

The following functions should not be called directly - the arguments should be passed to Table()/Table.read(), Table.write(), TableSet()/TableSet.read(), and TableSet.write() respectively.

atpy.votable.read(self, filename, pedantic=False, tid=-1, verbose=True)

Read a table from a VOT file

Required Arguments:

filename: [ string ]

The VOT file to read the table from

Optional Keyword Arguments:

tid: [ integer ]

The ID of the table to read from the VO file (this is only required if there are more than one table in the VO file)

pedantic: [ True | False ]

When pedantic is True, raise an error when the file violates the VO Table specification, otherwise issue a warning.

atpy.votable.write(self, filename, votype='ascii', overwrite=False)

Write the table to a VOT file

Required Arguments:

filename: [ string ]

The VOT file to write the table to

Optional Keyword Arguments:

votype: [ ‘ascii’ | ‘binary’ ]

Whether to write the table as ASCII or binary

atpy.votable.read_set(self, filename, pedantic=False, verbose=True)

Read all tables from a VOT file

Required Arguments:

filename: [ string ]

The VOT file to read the tables from

Optional Keyword Arguments:

pedantic: [ True | False ]

When pedantic is True, raise an error when the file violates the VO Table specification, otherwise issue a warning.

atpy.votable.write_set(self, filename, votype='ascii', overwrite=False)

Write all tables to a VOT file

Required Arguments:

filename: [ string ]

The VOT file to write the tables to

Optional Keyword Arguments:

votype: [ ‘ascii’ | ‘binary’ ]

Whether to write the tables as ASCII or binary tables