Source code for pyvo.dal.sia

# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
A module for searching for images in a remote archive.

A Simple Image Access (SIA) service allows a client to search for
images in an archive whose field of view overlaps with a given
rectangular region on the sky.  The service responds to a search query
with a table in which each row represents an image that is available
for download.  The columns provide metadata describing each image and
one column in particular provides the image's download URL (also
called the *access reference*, or *acref*).  Some SIA services act as
a cut-out service; in this case, the query result is a table of images
whose field of view matches the requested region and which will be
created when accessed via the download URL.

This module provides an interface for accessing an SIA service.  It is 
implemented as a specialization of the DAL Query interface.

The ``search()`` function support the simplest and most common types
of queries, returning an SIAResults instance as its results which
represents the matching imagess from the archive.  The SIAResults
supports access to and iterations over the individual records; these
are provided as SIARecord instances, which give easy access to key
metadata in the response, such as the position of the image's center,
the image format, the size and shape of the image, and its download
URL.

For more complex queries, the ``SIAQuery`` class can be helpful which 
allows one to build up, tweak, and reuse a query.  The ``SIAService``
class can represent a specific service available at a URL endpoint.
"""


import numbers, re, sys
from . import query

__all__ = [ "search", "SIAService", "SIAQuery", "SIAResults", "SIARecord" ]



[docs]class SIARecord(query.Record): """ a dictionary-like container for data in a record from the results of an image (SIA) search, describing an available image. The commonly accessed metadata which are stadardized by the SIA protocol are available as attributes. If the metadatum accessible via an attribute is not available, the value of that attribute will be None. All metadata, including non-standard metadata, are acessible via the ``get(`` *key* ``)`` function (or the [*key*] operator) where *key* is table column name. """ def __init__(self, results, index): super(SIARecord, self).__init__(results, index) self._ucdcols = results._siacols self._names = results._recnames @property def ra(self): """ return the right ascension of the center of the image """ return self.get(self._names["ra"]) @property def dec(self): """ return the declination of the center of the image """ return self.get(self._names["dec"]) @property def title(self): """ the title of the image """ return self.get(self._names["title"]) @property def format(self): """ the format of the image """ return self.get(self._names["format"]) @property def dateobs(self): """ the modified Julien date (MJD) of the mid-point of the observational data that went into the image """ return self.get(self._names["dateobs"]) @property def naxes(self): """ the number of axes in this image. """ return self.get(self._names["naxes"]) @property def naxis(self): """ the lengths of the sides along each axis, in pixels, as a sequence """ return tuple(self.get(self._names["naxis"])) @property def instr(self): """ the name of the instrument (or instruments) that produced the data that went into this image. """ return self.get(self._names["instr"]) @property def acref(self): """ the URL that can be used to retrieve the image """ return self.get_str(self._names["acref"])
[docs] def getdataurl(self): """ return the URL contained in the access URL column which can be used to retrieve the dataset described by this record. None is returned if no such column exists. """ return self.acref
[docs] def suggest_dataset_basename(self): """ return a default base filename that the dataset available via ``getdataset()`` can be saved as. This function is specialized for a particular service type this record originates from so that it can be used by ``cachedataset()`` via ``make_dataset_filename()``. """ out = self.title if query._is_python3 and isinstance(out, bytes): out = out.decode('utf-8') if not out: out = "image" else: out = re.sub(r'\s+', '_', out.strip()) return out
[docs] def suggest_extension(self, default=None): """ returns a recommended filename extension for the dataset described by this record. Typically, this would look at the column describing the format and choose an extension accordingly. """ return query.mime2extension(self.format, default)
[docs]class SIAResults(query.DALResults): """ The list of matching images resulting from an image (SIA) query. Each record contains a set of metadata that describes an available image matching the query constraints. The number of records in the results is available via the :py:attr:`nrecs` attribute or by passing it to the Python built-in ``len()`` function. This class supports iterable semantics; thus, individual records (in the form of :py:class:`~pyvo.dal.sia.SIARecord` instances) are typically accessed by iterating over an ``SIAResults`` instance. >>> results = pyvo.imagesearch(url, pos=[12.24, -13.1], size=0.1) >>> for image in results: ... print(("{0}: {1}".format(image.title, title.getdataurl()))) Alternatively, records can be accessed randomly via :py:meth:`getrecord` or through a Python Database API (v2) Cursor (via :py:meth:`~pyvo.dal.query.DALResults.cursor`). Column-based data access is possible via the :py:meth:`~pyvo.dal.query.DALResults.getcolumn` method. ``SIAResults`` is essentially a wrapper around an Astropy :py:mod:`~astropy.io.votable` :py:class:`~astropy.io.votable.tree.Table` instance where the columns contain the various metadata describing the images. One can access that VOTable directly via the :py:attr:`~pyvo.dal.query.DALResults.votable` attribute. Thus, when one retrieves a whole column via :py:meth:`~pyvo.dal.query.DALResults.getcolumn`, the result is a Numpy array. Alternatively, one can manipulate the results as an Astropy :py:class:`~astropy.table.table.Table` via the following conversion: >>> table = results.votable.to_table() ``SIAResults`` supports the array item operator ``[...]`` in a read-only context. When the argument is numerical, the result is an :py:class:`~pyvo.dal.sia.SIARecord` instance, representing the record at the position given by the numerical index. If the argument is a string, it is interpreted as the name of a column, and the data from the column matching that name is returned as a Numpy array. """ RECORD_CLASS = SIARecord def __init__(self, votable, url=None): """ initialize the cursor. This constructor is not typically called by directly applications; rather an instance is obtained from calling a SIAQuery's execute(). """ super(SIAResults, self).__init__(votable, url, "sia", "1.0") self._siacols = { "VOX:Image_Title": self.fieldname_with_ucd("VOX:Image_Title"), "INST_ID": self.fieldname_with_ucd("INST_ID"), "VOX:Image_MJDateObs": self.fieldname_with_ucd("VOX:Image_MJDateObs"), "POS_EQ_RA_MAIN": self.fieldname_with_ucd("POS_EQ_RA_MAIN"), "POS_EQ_DEC_MAIN": self.fieldname_with_ucd("POS_EQ_DEC_MAIN"), "VOX:Image_Naxes": self.fieldname_with_ucd("VOX:Image_Naxes"), "VOX:Image_Naxis": self.fieldname_with_ucd("VOX:Image_Naxis"), "VOX:Image_Scale": self.fieldname_with_ucd("VOX:Image_Scale"), "VOX:Image_Format": self.fieldname_with_ucd("VOX:Image_Format"), "VOX:STC_CoordRefFrame": self.fieldname_with_ucd("VOX:STC_CoordRefFrame"), "VOX:STC_CoordEquinox": self.fieldname_with_ucd("VOX:STC_CoordEquinox"), "VOX:WCS_CoordProjection": self.fieldname_with_ucd("VOX:WCS_CoordProjection"), "VOX:WCS_CoordRefPixel": self.fieldname_with_ucd("VOX:WCS_CoordRefPixel"), "VOX:WCS_CoordRefValue": self.fieldname_with_ucd("VOX:WCS_CoordRefValue"), "VOX:WCS_CDMatrix": self.fieldname_with_ucd("VOX:WCS_CDMatrix"), "VOX:BandPass_ID": self.fieldname_with_ucd("VOX:BandPass_ID"), "VOX:BandPass_Unit": self.fieldname_with_ucd("VOX:BandPass_Unit"), "VOX:BandPass_RefValue": self.fieldname_with_ucd("VOX:BandPass_RefValue"), "VOX:BandPass_HiLimit": self.fieldname_with_ucd("VOX:BandPass_HiLimit"), "VOX:BandPass_LoLimit": self.fieldname_with_ucd("VOX:BandPass_LoLimit"), "VOX:Image_PixFlags": self.fieldname_with_ucd("VOX:Image_PixFlags"), "VOX:Image_AccessReference": self.fieldname_with_ucd("VOX:Image_AccessReference"), "VOX:Image_AccessRefTTL": self.fieldname_with_ucd("VOX:Image_AccessRefTTL"), "VOX:Image_FileSize": self.fieldname_with_ucd("VOX:Image_FileSize") } self._recnames = { "title": self._siacols["VOX:Image_Title"], "ra": self._siacols["POS_EQ_RA_MAIN"], "dec": self._siacols["POS_EQ_DEC_MAIN"], "instr": self._siacols["INST_ID"], "dateobs": self._siacols["VOX:Image_MJDateObs"], "format": self._siacols["VOX:Image_Format"], "naxes": self._siacols["VOX:Image_Naxes"], "naxis": self._siacols["VOX:Image_Naxis"], "acref": self._siacols["VOX:Image_AccessReference"] }
[docs]class SIAQuery(query.DALQuery): """ a class for preparing an query to an SIA service. Query constraints are added via its service type-specific methods. The various execute() functions will submit the query and return the results. The base URL for the query, which controls where the query will be sent when one of the execute functions is called, is typically set at construction time; however, it can be updated later via the :py:attr:`~pyvo.dal.query.DALQuery.baseurl` to send a configured query to another service. In addition to the search constraint attributes described below, search parameters can be set generically by name via dict semantics. The class attribute, ``std_parameters``, list the parameters defined by the SIA standard. The typical function for submitting the query is ``execute()``; however, alternate execute functions provide the response in different forms, allowing the caller to take greater control of the result processing. """ RESULTS_CLASS = SIAResults std_parameters = [ "POS", "SIZE", "INTERSECT", "NAXIS", "CFRAME", "EQUINOX", "CRPIX", "CRVAL", "CDELT", "ROTANG", "PROJ", "FORMAT", "VERB" ] allowed_intersects = "COVERS ENCLOSED CENTER OVERLAPS".split() def __init__(self, baseurl, version="1.0"): """ initialize the query object with a baseurl """ super(SIAQuery, self).__init__(baseurl, "sia", version) @property def pos(self): """ the position (POS) constraint as a 2-element tuple denoting RA and declination in decimal degrees. This defaults to None. """ return self.get("POS") @pos.setter def pos(self, pair): # do a check on the input if (isinstance(pair, list)): pair = tuple(pair) if (isinstance(pair, tuple)): if len(pair) != 2: raise ValueError("Wrong number of elements in pos list: " + str(pair)) if (not isinstance(pair[0], numbers.Number) or not isinstance(pair[1], numbers.Number)): raise ValueError("Wrong type of elements in pos list: " + str(pair)) else: raise ValueError("pos not a 2-element sequence") if pair[1] > 90.0 or pair[1] < -90.0: raise ValueError("pos declination out-of-range: " + str(pair[1])) while pair[0] < 0: pair = (pair[0]+360.0, pair[1]) while pair[0] >= 360.0: pair = (pair[0]-360.0, pair[1]) self["POS"] = pair @pos.deleter def pos(self): del self['POS'] @property def ra(self): """ the right ascension part of the position constraint (default: None). If this is set but dec has not been set yet, dec will be set to 0.0. """ if not self.pos: return None return self.pos[0] @ra.setter def ra(self, val): if not self.pos: self.pos = (0.0, 0.0) self.pos = (val, self.pos[1]) @property def dec(self): """ the declination part of the position constraint (default: None). If this is set but ra has not been set yet, ra will be set to 0.0. """ if not self.pos: return None return self.pos[1] @dec.setter def dec(self, val): if not self.pos: self.pos = (0.0, 0.0) self.pos = (self.pos[0], val) @property def size(self): """ a 2-element tuple giving the size of the rectangular search region along the right-ascension and declination directions, measured in decimal degrees. """ return self.get("SIZE") @size.setter def size(self, val): # do a check on the input if (isinstance(val, numbers.Number)): val = (val, val) elif (isinstance(val, list)): val = tuple(val) if (isinstance(val, tuple)): if len(val) != 2: raise ValueError("Wrong number of elements in size seq: " + str(val)) if (not isinstance(val[0], numbers.Number) or not isinstance(val[1], numbers.Number)): raise ValueError("Wrong type of elements in size seq: " + str(val)) else: raise ValueError("size not a 2-element number sequence: " + str(val)) if val[1] > 180.0 or val[1] <= 0.0: raise ValueError("declination size out-of-range: " + str(val[1])) if val[0] > 360.0 or val[0] <= 0.0: raise ValueError("ra size out-of-range: " + str(val[1])) # do check on val; convert single number to a pair self["SIZE"] = val @size.deleter def size(self): del self["SIZE"] @property def format(self): """ the desired format of the images to be returned. This will be in the form of a MIME-type (e.g. "image/fits") or one of the following special values. (Lower case are accepted when setting.) Special Values: =========== ==================================================== ALL all formats available GRAPHIC any graphical format (e.g. JPEG, PNG, GIF) GRAPHIC-ALL all graphical formats available METADATA no images reqested; only an empty table with fields properly specified =========== ==================================================== In addition, a value of "GRAPHIC-*fmt[,fmt]*" where *fmt* is graphical format type (e.g. "jpeg", "png", "gif") indicates that a graphical format is desired with a preference for _fmt_ in the order given. """ return self.get("FORMAT") @format.setter def format(self, val): if isinstance(val, str): uval = val.upper() if uval in ["ALL", "GRAPHIC", "GRAPHIC-ALL", "METADATA"]: val = uval elif uval.startswith("GRAPHIC-"): val = uval[:8] + val[8:] elif ',' in val: # can be a comma-separated list of MIME-types self.format = val.split(',') elif not query.is_mime_type(val): raise ValueError("Not a MIME-type or special value: " + val) elif hasattr(val, "__iter__"): # accept python iterables of MIME-types if len(val) == 0: del self["FORMAT"] return elif len(val) == 1: self.format = list(val)[0] return bad = [f for f in val if not query.is_mime_type(f)] if len(bad) > 0: raise ValueError("format list can only contain MIME-types; " + "(bad values: " + ','.join(bad) + ')') val = ','.join(val) self["FORMAT"] = val @format.deleter def format(self): del self["FORMAT"] @property def intersect(self): """ the search constraint that controls how images that overlap the search region are selected. Allowed (case-insensitive) values include: ========= ====================================================== COVERS select images that completely cover the search region ENCLOSED select images that are complete enclosed by the region OVERLAPS select any image that overlaps with the search region CENTER select images whose center is within the search region ========= ====================================================== """ return self.get("INTERSECT") @intersect.setter def intersect(self, val): if not isinstance(val, str): raise ValueError("intersect value not a string") val = val.upper() if val not in self.allowed_intersects: raise ValueError("unrecogized intersect value: " + val) self["INTERSECT"] = val @intersect.deleter def intersect(self): del self["INTERSECT"] @property def verbosity(self): """ an integer indicating the amount of metadata (i.e. columns) that will be returned by a query where 0 is the minimum amount and 3 is the maximum available. """ return self.get("VERB") @verbosity.setter def verbosity(self, val): # do a check on val if not isinstance(val, int): raise ValueError("verbosity value not an integer: " + val) self["VERB"] = val @verbosity.deleter def verbosity(self): del self["VERB"]
[docs]class SIAService(query.DALService): """ a representation of an SIA service """ QUERY_CLASS = SIAQuery def __init__(self, baseurl, resmeta=None, version="1.0"): """ instantiate an SIA service Parameters ---------- baseurl : str the base URL for submitting search queries to the service. resmeta : str an optional dictionary of properties about the service """ super(SIAService, self).__init__(baseurl, "sia", version, resmeta)
[docs] def search(self, pos, size, format='all', intersect="overlaps", verbosity=2, **keywords): """ submit a simple SIA query to this service with the given constraints. This method is provided for a simple but typical SIA queries. For more complex queries, one should create an SIAQuery object via create_query() Parameters ---------- pos : 2-element tuple of floats the ICRS RA and Dec of the center of the search region in decimal degrees size : a float or a 2-element sequence of floats the full rectangular size of the search region along the RA and Dec directions in decimal degrees format : str the image format(s) of interest. "all" (default) indicates all available formats; "graphic" indicates graphical images (e.g. jpeg, png, gif; not FITS); "metadata" indicates that no images should be returned--only an empty table with complete metadata; "image/\*" indicates a particular image format where * can have values like "fits", "jpeg", "png", etc. intersect : str a token indicating how the returned images should intersect with the search region; recognized values include: ========= ====================================================== COVERS select images that completely cover the search region ENCLOSED select images that are complete enclosed by the region OVERLAPS select any image that overlaps with the search region CENTER select images whose center is within the search region ========= ====================================================== verbosity : str an integer value that indicates the volume of columns to return in the result table. 0 means the minimum set of columsn, 3 means as many columns as are available. **keywords : additional parameters can be given via arbitrary keyword arguments. These can be either standard parameters (with names drown from the ``SIAQuery.std_parameters`` list) or paramters custom to the service. Where there is overlap with the parameters set by the other arguments to this function, these keywords will override. Returns ------- SIAResults a container holding a table of matching catalog records Raises ------ DALServiceError for errors connecting to or communicating with the service DALQueryError if the service responds with an error, including a query syntax error. See Also -------- SIAResults pyvo.dal.query.DALServiceError pyvo.dal.query.DALQueryError """ q = self.create_query(pos, size, format, intersect, verbosity, **keywords) return q.execute()
[docs] def create_query(self, pos=None, size=None, format=None, intersect=None, verbosity=None, **keywords): """ create a query object that constraints can be added to and then executed. The input arguments will initialize the query with the given values. Parameters ---------- pos : 2-element tuple of floats a 2-element tuple giving the ICRS RA and Dec of the center of the search region in decimal degrees size : 2-element tuple of floats a 2-element tuple giving the full rectangular size of the search region along the RA and Dec directions in decimal degrees format : str the image format(s) of interest. "all" indicates all available formats; "graphic" indicates graphical images (e.g. jpeg, png, gif; not FITS); "metadata" indicates that no images should be returned--only an empty table with complete metadata; "image/\*" indicates a particular image format where * can have values like "fits", "jpeg", "png", etc. intersect : str a token indicating how the returned images should intersect with the search region; recognized values include: ========= ====================================================== COVERS select images that completely cover the search region ENCLOSED select images that are complete enclosed by the region OVERLAPS select any image that overlaps with the search region CENTER select images whose center is within the search region ========= ====================================================== verbosity : int an integer value that indicates the volume of columns to return in the result table. 0 means the minimum set of columsn, 3 means as many columns as are available. **keywords : additional parameters can be given via arbitrary keyword arguments. These can be either standard parameters (with names drown from the ``SIAQuery.std_parameters`` list) or paramters custom to the service. Where there is overlap with the parameters set by the other arguments to this function, these keywords will override. Returns ------- SIAQuery the query instance See Also -------- SIAQuery """ q = self.QUERY_CLASS(self.baseurl, self.version) if pos is not None: q.pos = pos if size is not None: q.size = size if format: q.format = format if intersect: q.intersect = intersect if verbosity is not None: q.verbosity = verbosity q.update(keywords) return q