DALResults

class pyvo.dal.query.DALResults(votable, url=None, protocol=None, version=None)[source]

Bases: object

Results from a DAL query. It provides random access to records in the response. Alternatively, it can provide results via a Cursor (compliant with the Python Database API) or an iterable.

initialize the cursor. This constructor is not typically called by directly applications; rather an instance is obtained from calling a DALQuery’s execute().

Parameters:

votable : str

the service response parsed into an astropy.io.votable.tree.VOTableFile instance.

url : str

the URL that produced the response

protocol : str

the name of the protocol that this response (supposedly) complies with

version : str

the version of the protocol that this response (supposedly) complies with

Raises:

DALFormatError

if the response VOTable does not contain a response table

See also

DALFormatError

Attributes Summary

nrecs the number of records returned in this result (read-only)
protocol The service protocol which generated this query response (read-only).
queryurl the URL query that produced these results. None is returned if unknown
table the astropy table object
version The version of the service protocol which generated this query response (read-only).

Methods Summary

cursor() return a cursor that is compliant with the Python Database API’s
fielddesc() return the full metadata for a column as Field instance, a simple
fieldname_with_ucd(ucd) return the field name that has a given UCD value or None if the UCD
fieldname_with_utype(utype) return the field name that has a given UType value or None if the UType
fieldnames() return the names of the columns. These are the names that are used
getcolumn(name) return a numpy array containing the values for the column with the
getdesc(name) return the field description for the record attribute (column) with
getrecord(index) return a representation of a result record that follows dictionary
getvalue(name, index) return the value of a record attribute–a value from a column and row.

Attributes Documentation

nrecs

the number of records returned in this result (read-only)

protocol

The service protocol which generated this query response (read-only).

queryurl

the URL query that produced these results. None is returned if unknown

table

the astropy table object

version

The version of the service protocol which generated this query response (read-only).

Methods Documentation

cursor()[source]

return a cursor that is compliant with the Python Database API’s Cursor interface. See PEP 249 for details.

fielddesc()[source]

return the full metadata for a column as Field instance, a simple object with attributes corresponding the the VOTable FIELD attributes, namely: name, id, type, ucd, utype, arraysize, description

fieldname_with_ucd(ucd)[source]

return the field name that has a given UCD value or None if the UCD is not found. None is also returned if the UCD is None or an empty stirng

fieldname_with_utype(utype)[source]

return the field name that has a given UType value or None if the UType is not found. None is also returned if UType is None or an empty stirng

fieldnames()[source]

return the names of the columns. These are the names that are used to access values from the dictionaries returned by getrecord(). They correspond the ID of the column, if it is set, or otherwise to the column name.

getcolumn(name)[source]

return a numpy array containing the values for the column with the given name

getdesc(name)[source]

return the field description for the record attribute (column) with the given name

Parameters:

name : str

the name of the attribute (column), chosen from those in fieldnames()

Returns:

object

with attributes (name, id, datatype, unit, ucd, utype, arraysize) which describe the column

getrecord(index)[source]

return a representation of a result record that follows dictionary semantics. The keys of the dictionary are those returned by this instance’s fieldNames() function: either the column IDs or name, if the ID is not set. The returned record may have additional accessor methods for getting at stardard DAL response metadata (e.g. ra, dec).

Parameters:

index : int

the integer index of the desired record where 0 returns the first record

Returns:

Record

a dictionary-like wrapper containing the result record metadata.

Raises:

IndexError

if index is negative or equal or larger than the number of rows in the result table.

See also

Record

getvalue(name, index)[source]

return the value of a record attribute–a value from a column and row.

Parameters:

name : str

the name of the attribute (column)

index : int

the zero-based index of the record

Raises:

IndexError

if index is negative or equal or larger than the number of rows in the result table.

KeyError

if name is not a recognized column name