示例#1
0
class DKISTQueryResponseTable(QueryResponseTable):
    """
    Results of a DKIST Dataset search.
    """

    # Define some class properties to better format the results table.
    hide_keys: List[str] = [
        "Storage Bucket", "Full Stokes", "asdf Filename",
        "Recipie Instance ID", "Recipie Run ID", "Recipe ID", "Movie Filename",
        "Level 0 Frame count", "Creation Date", "Last Updated",
        "Experiment IDs", "Proposal IDs", "Preview URL"
    ]

    # These keys are shown in the repr and str representations of this class.
    _core_keys = TableAttribute(
        default=["Start Time", "End Time", "Instrument", "Wavelength"])

    # Map the keys in the response to human friendly ones.
    key_map: Mapping[str, str] = DefaultMap(
        None, {
            "asdfObjectKey": "asdf Filename",
            "boundingBox": "Bounding Box",
            "browseMovieObjectKey": "Movie Filename",
            "browseMovieUrl": "Preview URL",
            "bucket": "Storage Bucket",
            "contributingExperimentIds": "Experiment IDs",
            "contributingProposalIds": "Proposal IDs",
            "createDate": "Creation Date",
            "datasetId": "Dataset ID",
            "datasetSize": "Dataset Size",
            "embargoEndDate": "Embargo End Date",
            "endTime": "End Time",
            "experimentDescription": "Experiment Description",
            "exposureTime": "Exposure Time",
            "filterWavelengths": "Filter Wavelengths",
            "frameCount": "Number of Frames",
            "hasAllStokes": "Full Stokes",
            "instrumentName": "Instrument",
            "isDownloadable": "Downloadable",
            "isEmbargoed": "Embargoed",
            "observables": "Observables",
            "originalFrameCount": "Level 0 Frame count",
            "primaryExperimentId": "Primary Experiment ID",
            "primaryProposalId": "Primary Proposal ID",
            "qualityAverageFriedParameter": "Average Fried Parameter",
            "qualityAveragePolarimetricAccuracy":
            "Average Polarimetric Accuracy",
            "recipeId": "Recipe ID",
            "recipeInstanceId": "Recipie Instance ID",
            "recipeRunId": "Recipie Run ID",
            "startTime": "Start Time",
            "stokesParameters": "Stokes Parameters",
            "targetTypes": "Target Types",
            "updateDate": "Last Updated",
            "wavelengthMax": "Wavelength Max",
            "wavelengthMin": "Wavelength Min",
        })

    @staticmethod
    def _process_table(
            results: "DKISTQueryResponseTable") -> "DKISTQueryResponseTable":
        times = [
            "Creation Date", "End Time", "Start Time", "Last Updated",
            "Embargo End Date"
        ]
        units = {
            "Exposure Time": u.s,
            "Wavelength Min": u.nm,
            "Wavelength Max": u.nm,
            "Dataset Size": u.Gibyte,
            "Filter Wavelengths": u.nm
        }

        for colname in times:
            if colname not in results.colnames:
                continue  # pragma: no cover
            if not any([v is None for v in results[colname]]):
                results[colname] = Time(results[colname])

        for colname, unit in units.items():
            if colname not in results.colnames:
                continue  # pragma: no cover
            results[colname] = u.Quantity(results[colname], unit=unit)

        if results:
            results["Wavelength"] = u.Quantity(
                [results["Wavelength Min"], results["Wavelength Max"]]).T
            results.remove_columns(("Wavelength Min", "Wavelength Max"))

        return results

    @classmethod
    def from_results(
            cls, results: Iterable[Mapping[str, Any]], *,
            client: "DKISTDatasetClient") -> "DKISTQueryResponseTable":
        """
        Construct the results table from the API results.
        """
        new_results = defaultdict(list)
        for result in results:
            for key, value in result.items():
                new_results[cls.key_map[key]].append(value)

        data = cls._process_table(cls(new_results, client=client))
        data = data._reorder_columns(cls._core_keys.default, remove_empty=True)

        return data
示例#2
0
class QueryResponseTable(QTable):
    __doc__ = QTable.__doc__

    Row = QueryResponseRow
    Column = QueryResponseColumn

    client = TableAttribute()
    display_keys = TableAttribute(default=slice(None))
    hide_keys = TableAttribute()

    size_column = None

    def unhide_columns(self):
        """
        Modify this table so that all columns are displayed.
        """
        self.display_keys = slice(None)
        self.hide_keys = None
        return self

    def _reorder_columns(self, first_columns, remove_empty=True):
        """
        Generate a new version of this table with ``first_columns`` at the start.

        Parameters
        ----------
        first_columns : list
           The column names to put at the start of the table.
        remove_empty : bool, optional
           Remove columns where all values are `None`.
           Defaults to ``True``.

        Returns
        -------
        new_table : QueryResponseTable
            A sliced version of this table instance so that the columns are
            reordered.
        """
        all_cols = list(self.colnames)
        first_names = [n for n in first_columns if n in all_cols]
        extra_cols = [col for col in all_cols if col not in first_names]
        all_cols = first_names + extra_cols
        new_table = self[[col for col in all_cols if self[col] is not None]]

        if remove_empty:
            empty_cols = [
                col.info.name for col in self.itercols()
                if col.info.dtype.kind == 'O' and all(val is None
                                                      for val in col)
            ]
            new_table.remove_columns(empty_cols)

        return new_table

    @property
    def _display_table(self):
        """
        Apply the display_keys and hide_keys attributes to the table.

        This removes any keys in hide keys and then slices by any keys in
        display_keys to return the correct table.
        """

        keys = list(self.colnames)
        if self.hide_keys:
            # Index only the keys not in hide keys in order
            [keys.remove(key) for key in self.hide_keys if key in keys]

        if self.display_keys != slice(None):
            keys = [dk for dk in self.display_keys if dk in keys]

        table = self[keys]
        # The slicing operation resets display and hide keys to default, but we
        # have already applied it
        table.unhide_columns()

        return table

    def __str__(self):
        """Print out human-readable summary of records retrieved"""
        return '\n'.join(self._display_table.pformat(show_dtype=False))

    def __repr__(self):
        """Print out human-readable summary of records retrieved"""
        return object.__repr__(self) + "\n" + str(self._display_table)

    def _repr_html_(self):
        return QTable._repr_html_(self._display_table)

    def show(self, *cols):
        """
        Return a table with only ``cols`` present.

        If no ``cols`` are specified, all columns will be shown, including any
        hidden by default.

        This differs slightly from ``QueryResponseTable[cols]`` as it allows
        keys which are not in the table to be requested.
        """
        table = self.copy()
        table.unhide_columns()

        if len(cols) == 0:
            return table

        valid_cols = [col for col in cols if col in table.colnames]
        table = table[valid_cols]

        # The slicing operation resets display and hide keys to default, but we
        # want to bypass it here.
        table.unhide_columns()
        return table

    def path_format_keys(self):
        """
        Returns all the names that can be used to format filenames.

        Each one corresponds to a single column in the table, and the format
        syntax should match the dtype of that column, i.e. for a ``Time``
        object or a ``Quantity``.
        """
        rbp = set(self[0].response_block_map.keys())
        for row in self[1:]:
            rbp.intersection(row.response_block_map.keys())
        return rbp

    def total_size(self):
        """
        Returns the total size of all files in a query.

        Derived classes must set the 'size_column' class attribute to make use
        of this.
        """
        if self.size_column not in self.colnames:
            return np.nan * u.byte
        sizes = self[self.size_column]
        # Strip negative filesizes
        total = np.nansum(sizes[sizes > 0])
        if not (total > 0 * u.byte):
            return np.nan * u.byte
        # Find the first power of 3 below the total filesize
        power = 10**(np.floor(np.log10(total.to_value(u.byte)) // 3) * 3)
        # Create mapping from prefix value to prefix name
        prefix_dict = {p[2]: p[0][0] for p in u.si_prefixes}
        prefix_unit = u.Unit(f'{prefix_dict[power]}byte')
        return total.to(prefix_unit).round(3)
示例#3
0
class QueryResponseTable(QTable):
    __doc__ = QTable.__doc__

    Row = QueryResponseRow
    Column = QueryResponseColumn

    client = TableAttribute()
    display_keys = TableAttribute(default=slice(None))
    hide_keys = TableAttribute()

    # This is a work around for https://github.com/astropy/astropy/pull/11217
    # TODO Remove when min astropy version is > 4.2.1
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        for attr in list(kwargs):
            descr = getattr(self.__class__, attr, None)
            if isinstance(descr, TableAttribute):
                setattr(self, attr, kwargs.pop(attr))

    def unhide_columns(self):
        """
        Modify this table so that all columns are displayed.
        """
        self.display_keys = slice(None)
        self.hide_keys = None
        return self

    def _reorder_columns(self, first_columns, remove_empty=True):
        """
        Generate a new version of this table with ``first_columns`` at the start.

        Parameters
        ----------
        first_columns : list
           The column names to put at the start of the table.
        remove_empty : bool, optional
           Remove columns where all values are `None`.
           Defaults to ``True``.

        Returns
        -------
        new_table : QueryResponseTable
            A sliced version of this table instance so that the columns are
            reordered.
        """
        all_cols = list(self.colnames)
        first_names = [n for n in first_columns if n in all_cols]
        extra_cols = [col for col in all_cols if col not in first_names]
        all_cols = first_names + extra_cols
        new_table = self[[col for col in all_cols if self[col] is not None]]

        if remove_empty:
            empty_cols = [
                col.info.name for col in self.itercols()
                if col.info.dtype.kind == 'O' and all(val is None
                                                      for val in col)
            ]
            new_table.remove_columns(empty_cols)

        return new_table

    @property
    def _display_table(self):
        """
        Apply the display_keys and hide_keys attributes to the table.

        This removes any keys in hide keys and then slices by any keys in
        display_keys to return the correct table.
        """

        keys = list(self.colnames)
        if self.hide_keys:
            # Index only the keys not in hide keys in order
            [keys.remove(key) for key in self.hide_keys if key in keys]

        if self.display_keys != slice(None):
            keys = [dk for dk in self.display_keys if dk in keys]

        table = self[keys]
        # The slicing operation resets display and hide keys to default, but we
        # have already applied it
        table.unhide_columns()

        return table

    def __str__(self):
        """Print out human-readable summary of records retrieved"""
        return '\n'.join(self._display_table.pformat(show_dtype=False))

    def __repr__(self):
        """Print out human-readable summary of records retrieved"""
        return object.__repr__(self) + "\n" + str(self._display_table)

    def _repr_html_(self):
        return QTable._repr_html_(self._display_table)

    def show(self, *cols):
        """
        Return a table with only ``cols`` present.

        If no ``cols`` are specified, all columns will be shown, including any
        hidden by default.

        This differs slightly from ``QueryResponseTable[cols]`` as it allows
        keys which are not in the table to be requested.
        """
        table = self.copy()
        table.unhide_columns()

        if len(cols) == 0:
            return table

        valid_cols = [col for col in cols if col in table.colnames]
        table = table[valid_cols]

        # The slicing operation resets display and hide keys to default, but we
        # want to bypass it here.
        table.unhide_columns()
        return table

    def path_format_keys(self):
        """
        Returns all the names that can be used to format filenames.

        Each one corresponds to a single column in the table, and the format
        syntax should match the dtype of that column, i.e. for a ``Time``
        object or a ``Quantity``.
        """
        rbp = set(self[0].response_block_map.keys())
        for row in self[1:]:
            rbp.intersection(row.response_block_map.keys())
        return rbp
示例#4
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class VSOQueryResponseTable(QueryResponseTable):
    hide_keys = ['fileid', 'fileurl']
    errors = TableAttribute(default=[])

    @classmethod
    def from_zeep_response(cls, response, *, client, _sort=True):
        """
        Construct a table response from the zeep response.
        """
        # _sort is a hack to be able to convert from a legacy QueryResponse to
        # a table response.
        if _sort:
            records = iter_sort_response(response)
        else:
            records = response

        data = []
        for record in records:
            row = defaultdict(lambda: None)
            for key, value in serialize_object(record).items():
                if not isinstance(value, Mapping):
                    if key == "size":
                        # size is in bytes with a very high degree of precision.
                        value = (value * u.Kibyte).to(u.Mibyte).round(5)

                    key = key.capitalize() if key not in cls.hide_keys else key
                    row[key] = value
                else:
                    if key == "wave":
                        # Some records in the VSO have 'kev' which astropy
                        # doesn't recognise as a unit, so fix it.
                        waveunit = value['waveunit']
                        waveunit = 'keV' if waveunit == 'kev' else waveunit

                        row["Wavelength"] = None
                        if value['wavemin'] is not None and value[
                                'wavemax'] is not None:
                            row["Wavelength"] = u.Quantity([
                                float(value['wavemin']),
                                float(value['wavemax'])
                            ],
                                                           unit=waveunit)

                        row["Wavetype"] = value['wavetype']
                        continue
                    for subkey, subvalue in value.items():
                        key_template = f"{key.capitalize()} {subkey.capitalize()}"
                        if key == "time" and subvalue is not None:
                            key_template = f"{subkey.capitalize()} {key.capitalize()}"
                            subvalue = parse_time(subvalue)
                            # Change the display to the 'T'-less version
                            subvalue.format = 'iso'
                        row[key_template] = subvalue
            data.append(row)

        # Reorder the columns to put the most useful ones first.
        data = cls(data, client=client)
        return data._reorder_columns([
            'Start Time', 'End Time', 'Source', 'Instrument', 'Type',
            'Wavelength'
        ],
                                     remove_empty=True)

    def total_size(self):
        if 'size' not in self.colnames:
            return np.nan
        return np.nansum(self['size'])

    def add_error(self, exception):
        self.errors.append(exception)
示例#5
0
class Features(Table):
    """A class for holding PAHFIT features and their associated
    parameter information.  Note that each parameter has an associated
    `kind', and that each kind has an associated set of allowable
    parameters (see _kind_params, below).
    """

    TableFormatter = BoundedParTableFormatter
    MaskedColumn = BoundedMaskedColumn

    param_covar = TableAttribute(default=[])
    _kind_params = {
        'starlight': {'temperature', 'tau'},
        'dust_continuum': {'temperature', 'tau'},
        'line': {'wavelength', 'power'},  # 'fwhm', Instrument Pack detail!
        'dust_feature': {'wavelength', 'fwhm', 'power'},
        'attenuation': {'model', 'tau', 'geometry'},
        'absorption': {'wavelength', 'fwhm', 'tau', 'geometry'}
    }

    _units = {'temperature': u.K, 'wavelength': u.um, 'fwhm': u.um}
    _group_attrs = set(
        ('bounds', 'features', 'kind'))  # group-level attributes
    _param_attrs = set(
        ('value', 'bounds'))  # Each parameter can have these attributes
    _no_bounds = set(('name', 'group', 'geometry',
                      'model'))  # String attributes (no bounds)

    @classmethod
    def read(cls, file, *args, **kwargs):
        """Read a table from file.

        If reading a YAML file, read it in as a science pack and
        return the new table. Otherwise, use astropy's normal Table
        reader.
        """
        if file.endswith(".yaml") or file.endswith(".yml"):
            return cls._read_scipack(file)
        else:
            return super().read(file, *args, **kwargs)

    @classmethod
    def _read_scipack(cls, file):
        """Read a science pack specification from YAML file.

        Arguments:
        ----------

          file: the name of the file, either a full valid path, or
            named file in the PAHFIT science_packs directory.!

        Returns:
        --------

          table: A filled pahfit.features.Features table.
        """

        feat_tables = dict()

        if not os.path.isfile(file):
            pack_path = resource_filename("pahfit", "packs/science")
            file = os.path.join(pack_path, file)
        try:
            with open(file) as fd:
                scipack = yaml.load(fd, Loader=UniqueKeyLoader)
        except IOError as e:
            raise PAHFITFeatureError("Error reading science pack file\n"
                                     f"\t{file}\n\t{repr(e)}")
        for (name, elem) in scipack.items():
            try:
                keys = elem.keys()
            except AttributeError:
                raise PAHFITFeatureError("Invalid science pack"
                                         f" format at {name}\n\t{file}")

            try:
                kind = elem.pop('kind')
            except KeyError:
                raise PAHFITFeatureError(f"No kind found for {name}\n\t{file}")

            try:
                valid_params = cls._kind_params[kind]
            except KeyError:
                raise PAHFITFeatureError(
                    f"Unknown kind {kind} for {name}\n\t{file}")
            unknown_params = [
                x for x in keys
                if not (x in valid_params or x in cls._group_attrs)
            ]
            if unknown_params:
                raise PAHFITFeatureError(
                    f"Unknown {kind} parameters:"
                    f" {', '.join(unknown_params)}\n\t{file}")

            hasFeatures = 'features' in elem
            hasLists = any(k not in cls._group_attrs and (
                isinstance(v, (tuple, list)) or (isinstance(
                    v, dict) and cls._param_attrs.isdisjoint(v.keys())))
                           for (k, v) in elem.items())
            if hasFeatures and hasLists:
                raise PAHFITFeatureError(
                    "A single group cannot contain both 'features'"
                    f" and parameter list(s): {name}\n\t{file}")
            isGroup = (hasFeatures or hasLists)
            bounds = None
            if isGroup:  # A named group of features
                if 'bounds' in elem:
                    if not isinstance(elem['bounds'], dict):
                        for p in cls._no_bounds:
                            if p in elem:
                                raise PAHFITFeatureError(
                                    f"Parameter {p} cannot have "
                                    f"bounds: {name}\n\t{file}")
                        if sum(p in elem for p in valid_params) > 1:
                            raise PAHFITFeatureError(
                                "Groups with simple bounds "
                                "can only specify a single "
                                f"parameter: {name}\n\t{file}")
                        if hasFeatures:
                            raise PAHFITFeatureError(
                                "Groups with simple bounds "
                                "cannot specify "
                                f"'features': {name}\n\t{file}")
                    bounds = elem.pop('bounds')
                if hasFeatures:  # our group uses a features dict
                    for n, v in elem['features'].items():
                        if bounds and 'bounds' not in v:  # inherit bounds
                            v['bounds'] = bounds
                        cls._add_feature(kind, feat_tables, n, group=name, **v)
                elif hasLists:  # a "shortcut" feature group, using lists
                    llen = []
                    for k, v in elem.items():
                        if k in cls._group_attrs:
                            continue
                        if not isinstance(v, (tuple, list, dict)):
                            raise PAHFITFeatureError(
                                f"All non-group parameters in {name} "
                                f"must be lists or dicts:\n\t{file}")
                        llen.append(len(v))

                    if not all(x == llen[0] for x in llen):
                        raise PAHFITFeatureError(
                            f"All parameter lists in group {name} "
                            f"must be the same length:\n\t{file}")
                    ngroup = llen[0]
                    feat_names = None
                    for k, v in elem.items():
                        if isinstance(elem[k], dict):
                            if not feat_names:  # First names win
                                feat_names = list(elem[k].keys())
                            elem[k] = list(elem[k].values()
                                           )  # turn back into a value list
                    if not feat_names:  # no names: construct one for each group feature
                        feat_names = [f"{name}{x:02}" for x in range(ngroup)]
                    for i in range(
                            ngroup):  # Iterate over list(s) adding feature
                        v = {k: elem[k][i] for k in valid_params if k in elem}
                        cls._add_feature(kind,
                                         feat_tables,
                                         feat_names[i],
                                         group=name,
                                         bounds=bounds,
                                         **v)
                else:
                    raise PAHFITFeatureError(
                        f"Group {name} needs either 'features' or"
                        f"parameter list(s):\n\t{file}")
            else:  # Just one standalone feature
                cls._add_feature(kind, feat_tables, name, **elem)
        return cls._construct_table(feat_tables)

    @classmethod
    def _add_feature(cls,
                     kind: str,
                     t: dict,
                     name: str,
                     *,
                     bounds=None,
                     group='_none_',
                     **pars):
        """Adds an individual feature to the passed dictionary t."""
        if kind not in t:
            t[kind] = {}  # group by kind
        if name not in t[kind]:
            t[kind][name] = {}
        t[kind][name]['group'] = group
        t[kind][name]['kind'] = kind
        for (param, val) in pars.items():
            if param not in cls._kind_params[kind]:
                continue
            if isinstance(val, dict):  # A param attribute dictionary
                unknown_attrs = [
                    x for x in val.keys() if x not in cls._param_attrs
                ]
                if unknown_attrs:
                    raise PAHFITFeatureError("Unknown parameter attributes for"
                                             f" {name} ({kind}, {group}): "
                                             f"{', '.join(unknown_attrs)}")
                if 'value' not in val:
                    raise PAHFITFeatureError("Missing 'value' attribute for "
                                             f"{name} ({kind}, {group})")
                value = val['value']
                if 'bounds' in val:  # individual param bounds
                    if param in cls._no_bounds:
                        raise PAHFITFeatureError(
                            "Parameter {param} cannot have bounds: "
                            f"{name} ({kind}, {group})")
                    bounds = val['bounds']
            else:
                value = val  # a bare value
            if isinstance(bounds, dict):
                b = bounds.get(param)
                if b and param in cls._no_bounds:
                    raise PAHFITFeatureError(
                        "Parameter {param} cannot have bounds: "
                        f"{name} ({kind}, {group})")
            else:  # Simple bounds
                b = bounds
            try:
                t[kind][name][param] = (value if param in cls._no_bounds else
                                        value_bounds(value, b))
            except ValueError as e:
                raise PAHFITFeatureError(
                    "Error initializing value and bounds for"
                    f" {name} ({kind}, {group}):\n\t{e}")

    @classmethod
    def _construct_table(cls, inp: dict):
        """Construct a masked table with units from input dictionary
        INP.  INP is a dictionary with feature names as the key, and a
        dictionary of feature parameters as value.  Each value in the
        feature parameter dictionary is either a value or tuple of 3
        values for bounds.
        """
        tables = []
        for (kind, features) in inp.items():
            kind_params = cls._kind_params[kind]  # All params for this kind
            rows = []
            for (name, params) in features.items():
                for missing in kind_params - params.keys():
                    if missing in cls._no_bounds:
                        params[missing] = 0.0
                    else:
                        params[missing] = value_bounds(0.0, bounds=(0.0, None))
                rows.append(dict(name=name, **params))
            table_columns = rows[0].keys()
            t = cls(rows, names=table_columns)
            for p in cls._kind_params[kind]:
                if p not in cls._no_bounds:
                    t[p].info.format = "0.4g"  # Nice format (customized by Formatter)
            tables.append(t)
        tables = vstack(tables)
        for cn, col in tables.columns.items():
            if cn in cls._units:
                col.unit = cls._units[cn]
        tables.add_index('name')
        return tables
示例#6
0
class VSOQueryResponseTable(QueryResponseTable):
    hide_keys = ['fileid', 'fileurl']
    errors = TableAttribute(default=[])
    size_column = 'Size'

    @classmethod
    def from_zeep_response(cls, response, *, client, _sort=True):
        """
        Construct a table response from the zeep response.
        """
        # _sort is a hack to be able to convert from a legacy QueryResponse to
        # a table response.
        if _sort:
            records = iter_sort_response(response)
        else:
            records = response

        data = []
        for record in records:
            row = defaultdict(lambda: None)
            for key, value in serialize_object(record).items():
                if not isinstance(value, Mapping):
                    if key == "size":
                        # size is in bytes with a very high degree of precision.
                        value = (value * u.Kibyte).to(u.Mibyte).round(5)

                    key = key.capitalize() if key not in cls.hide_keys else key
                    row[key] = value
                else:
                    if key == "wave":
                        # Some records in the VSO have 'kev' which astropy
                        # doesn't recognise as a unit, so fix it.
                        waveunit = value['waveunit']
                        waveunit = 'keV' if waveunit == 'kev' else waveunit

                        row["Wavelength"] = None
                        if value['wavemin'] is not None and value['wavemax'] is not None:
                            row["Wavelength"] = u.Quantity(
                                [float(value['wavemin']), float(value['wavemax'])],
                                unit=waveunit)

                        row["Wavetype"] = value['wavetype']
                        continue
                    for subkey, subvalue in value.items():
                        if key == "time" and subvalue is not None:
                            key_template = f"{subkey.capitalize()} {key.capitalize()}"
                        else:
                            key_template = f"{key.capitalize()} {subkey.capitalize()}"
                        row[key_template] = subvalue
            data.append(row)

        data = cls(data, client=client)
        # Parse times
        for col in data.colnames:
            if col.endswith('Time'):
                try:
                    # Try to use a vectorised call to parse_time
                    data[col] = parse_time(data[col])
                except Exception:
                    # If that fails, parse dates one by one. This is needed if
                    # VSO returns a variety of different date format strings
                    times = []
                    mask = []
                    for i, t in enumerate(data[col]):
                        if t is not None:
                            times.append(parse_time(t))
                        else:
                            # Create a dummy time and mask it later
                            times.append(Time(val=0, format='mjd'))
                            mask.append(i)
                    data[col] = Time(times)
                    data[col][mask] = np.ma.masked

                data[col].format = 'iso'

        # Reorder the columns to put the most useful ones first.
        return data._reorder_columns(['Start Time', 'End Time', 'Source',
                                      'Instrument', 'Type', 'Wavelength'],
                                     remove_empty=True)

    def add_error(self, exception):
        self.errors.append(exception)