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- Table

# Table

class astropy.io.votable.tree.Table(votable, ID=None, name=None, ref=None, ucd=None, utype=None, nrows=None, id=None, config=None, pos=None, **extra)

  Bases: `Element`, `_IDProperty`, `_NameProperty`, `_UcdProperty`, `_DescriptionProperty`

  TABLE element: optionally contains data.

  It contains the following publicly-accessible and mutable attribute:

  > array: A Numpy masked array of the data itself, where each row is a row of votable data, and columns are named and typed based on the <FIELD> elements of the table. The mask is parallel to the data array, except for variable-length fields. For those fields, the numpy array’s column type is “object” (`"O"`), and another masked array is stored there.

  If the Table contains no data, (for example, its enclosing `Resource` has `type` == ‘meta’) array will have zero-length.

  The keyword arguments correspond to setting members of the same name, documented below.

  Attributes Summary

  `fields` | A list of `Field` objects describing the types of each of the data columns.
  `format` | [required] The serialization format of the table.
  `groups` | A list of `Group` objects describing how the columns and parameters are grouped.
  `infos` | A list of `Info` objects for the table.
  `links` | A list of `Link` objects (pointers to other documents or servers through a URI) for the table.
  `nrows` | [immutable] The number of rows in the table, as specified in the XML file.
  `params` | A list of parameters (constant-valued columns) for the table.
  `ref` |

  Methods Summary

  `create_arrays`([nrows, config]) | Create a new array to hold the data based on the current set of fields, and store them in the array and member variable.
  `from_table`(votable, table) | Create a `Table` instance from a given `astropy.table.Table` instance.
  `get_field_by_id`(ref[, before]) | Looks up a FIELD or PARAM element by the given ID.
  `get_field_by_id_or_name`(ref[, before]) | Looks up a FIELD or PARAM element by the given ID or name.
  `get_fields_by_utype`(ref[, before]) | Looks up a FIELD or PARAM element by the given utype and returns an iterator emitting all matches.
  `get_group_by_id`(ref[, before]) | Looks up a GROUP element by the given ID.
  `get_groups_by_utype`(ref[, before]) | Looks up a GROUP element by the given utype and returns an iterator emitting all matches.
  `is_empty`() | Returns True if this table doesn't contain any real data because it was skipped over by the parser (through use of the `table_number` kwarg).
  `iter_fields_and_params`() | Recursively iterate over all FIELD and PARAM elements in the TABLE.
  `iter_groups`() | Recursively iterate over all GROUP elements in the TABLE.
  `iter_info`() |
  `parse`(iterator, config) | For internal use.
  `to_table`([use_names_over_ids]) | Convert this VO Table to an `astropy.table.Table` instance.
  `to_xml`(w, **kwargs) | For internal use.

  Attributes Documentation

  fields

    A list of `Field` objects describing the types of each of the data columns.

  format

    [required] The serialization format of the table. Must be one of:

    > ‘tabledata’ (TABLEDATA), ‘binary’ (BINARY), ‘binary2’ (BINARY2) ‘fits’ (FITS).

    Note that the ‘fits’ format, since it requires an external file, can not be written out. Any file read in with ‘fits’ format will be read out, by default, in ‘tabledata’ format.

    See Data Serialization Formats.

  groups

    A list of `Group` objects describing how the columns and parameters are grouped. Currently this information is only kept around for round-tripping and informational purposes.

  infos

    A list of `Info` objects for the table. Allows for post-operational diagnostics.

  links

    A list of `Link` objects (pointers to other documents or servers through a URI) for the table.

  nrows

    [immutable] The number of rows in the table, as specified in the XML file.

  params

    A list of parameters (constant-valued columns) for the table. Must contain only `Param` objects.

  ref

  Methods Documentation

  create_arrays(nrows=0, config=None)

    Create a new array to hold the data based on the current set of fields, and store them in the array and member variable. Any data in the existing array will be lost.

    nrows, if provided, is the number of rows to allocate.

  classmethod from_table(votable, table)

    Create a `Table` instance from a given `astropy.table.Table` instance.

  get_field_by_id(ref, before=None)

    Looks up a FIELD or PARAM element by the given ID.

  get_field_by_id_or_name(ref, before=None)

    Looks up a FIELD or PARAM element by the given ID or name.

  get_fields_by_utype(ref, before=None)

    Looks up a FIELD or PARAM element by the given utype and returns an iterator emitting all matches.

  get_group_by_id(ref, before=None)

    Looks up a GROUP element by the given ID. Used by the group’s “ref” attribute

  get_groups_by_utype(ref, before=None)

    Looks up a GROUP element by the given utype and returns an iterator emitting all matches.

  is_empty()

    Returns True if this table doesn’t contain any real data because it was skipped over by the parser (through use of the `table_number` kwarg).

  iter_fields_and_params()

    Recursively iterate over all FIELD and PARAM elements in the TABLE.

  iter_groups()

    Recursively iterate over all GROUP elements in the TABLE.

  iter_info()
  parse(iterator, config)

    For internal use. Parse the XML content of the children of the element.

    Parameters:
      iterator `xml` python:iterable

        An iterator over XML elements as returned by `get_xml_iterator`.

      config `python:dict`

        The configuration dictionary that affects how certain elements are read.

    Returns:
      self `Element`

        Returns self as a convenience.

  to_table(use_names_over_ids=False)

    Convert this VO Table to an `astropy.table.Table` instance.

    Parameters:
      use_names_over_ids bool, optional

        When `True` use the `name` attributes of columns as the names of columns in the `astropy.table.Table` instance. Since names are not guaranteed to be unique, this may cause some columns to be renamed by appending numbers to the end. Otherwise (default), use the ID attributes as the column names.

      .. warning::

        Variable-length array fields may not be restored identically when round-tripping through the `astropy.table.Table` instance.

  to_xml(w, **kwargs)

    For internal use. Output the element to XML.

    Parameters:
      w `astropy.utils.xml.writer.XMLWriter` `object`

        An XML writer to write to.

      **kwargs `python:dict`

        Any configuration parameters to control the output.