Initial draft of SpectrogramMeta classes

changelog/245.feature.rst

@@ -0,0 +1 @@
+Add ``SpectrogramMetaABC`` and ``SpectrogramMeta`` metadata classes backed by ``ndcube.meta.NDMeta`` with instrument specific subclasses ``WAVESMeta`` and ``CALISTOMeta`` providing typed property access to spectrogram metadata.

radiospectra/spectrogram/meta.py

@@ -0,0 +1,182 @@
+import abc
+
+from ndcube.meta import NDMeta, NDMetaABC
+
+__all__ = ["SpectrogramMetaABC", "SpectrogramMeta"]
+
+
+class SpectrogramMetaABC(NDMetaABC):
+    """
+    Abstract base class for all spectrogram metadata.
+    """
+
+    # Identification
+    @property
+    @abc.abstractmethod
+    def instrument(self):
+        pass
+
+    @property
+    @abc.abstractmethod
+    def observatory(self):
+        pass
+
+    @property
+    @abc.abstractmethod
+    def detector(self):
+        pass
+
+    @property
+    @abc.abstractmethod
+    def processing_level(self):
+        """The level to which the data has been processed."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def version(self):
+        """The data version."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def source_filename(self):
+        """The source filename."""
+        pass
+
+    # Time
+    @property
+    @abc.abstractmethod
+    def date_start(self):
+        """The start time of the observation."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def date_end(self):
+        """The end time of the observation."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def temporal_resolution(self):
+        """Temporal resolution, both raw and current."""
+        pass
+
+    # Frequency
+    @property
+    @abc.abstractmethod
+    def frequency_range(self):
+        """Start and end frequencies of the observation."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def frequency_resolution(self):
+        """Frequency resolution, both raw and current."""
+        pass
+
+    # Calibration and signal
+    @property
+    @abc.abstractmethod
+    def data_units(self):
+        """Units of the data (e.g. arbitrary, V^2/Hz, sfu, dB)."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def calibration_state(self):
+        """Calibration state."""
+        pass
+
+    @property
+    @abc.abstractmethod
+    def polarisation(self):
+        """Stokes parameter convention or polarization."""
+        pass
+
+    # Quality
+    @property
+    @abc.abstractmethod
+    def data_mask(self):
+        """Data mask."""
+        pass
+
+    # Position
+    @property
+    @abc.abstractmethod
+    def observer_location(self):
+        """Observer location."""
+        pass
+
+
+class SpectrogramMeta(NDMeta, SpectrogramMetaABC):
+    """
+    Base class for radio spectrogram metadata.
+
+    Backed by `ndcube.meta.NDMeta` (a `dict` subclass).
+    """
+
+    @property
+    def instrument(self):
+        return self["instrument"]
+
+    @property
+    def observatory(self):
+        return self["observatory"]
+
+    @property
+    def detector(self):
+        return self["detector"]
+
+    @property
+    def date_start(self):
+        return self["start_time"]
+
+    @property
+    def date_end(self):
+        return self["end_time"]
+
+    @property
+    def processing_level(self):
+        return self.get("processing_level")
+
+    @property
+    def version(self):
+        return self.get("version")
+
+    @property
+    def source_filename(self):
+        return self.get("source_filename")
+
+    @property
+    def temporal_resolution(self):
+        return self.get("temporal_resolution")
+
+    @property
+    def frequency_range(self):
+        return self.get("wavelength")
+
+    @property
+    def frequency_resolution(self):
+        return self.get("frequency_resolution")
+
+    @property
+    def data_units(self):
+        return self.get("data_units")
+
+    @property
+    def calibration_state(self):
+        return self.get("calibration_state")
+
+    @property
+    def polarisation(self):
+        return self.get("polarisation")
+
+    @property
+    def data_mask(self):
+        return self.get("data_mask")
+
+    @property
+    def observer_location(self):
+        return self.get("observer_location")

radiospectra/spectrogram/sources/callisto.py

@@ -1,9 +1,25 @@
 import astropy.units as u
 from astropy.coordinates.earth import EarthLocation
 
+from radiospectra.spectrogram.meta import SpectrogramMeta
 from radiospectra.spectrogram.spectrogrambase import GenericSpectrogram
 
-__all__ = ["CALISTOSpectrogram"]
+__all__ = ["CALISTOSpectrogram", "CALISTOMeta"]
+
+
+class CALISTOMeta(SpectrogramMeta):
+    """Metadata for e-CALLISTO spectrograms."""
+
+    @property
+    def observer_location(self):
+        """The location of the observatory."""
+        fits_meta = self.get("fits_meta")
+        if fits_meta:
+            lat = fits_meta.get("OBS_LAT", 0) * u.deg * (1.0 if fits_meta.get("OBS_LAC") == "N" else -1.0)
+            lon = fits_meta.get("OBS_LON", 0) * u.deg * (1.0 if fits_meta.get("OBS_LOC") == "E" else -1.0)
+            height = fits_meta.get("OBS_ALT", 0) * u.m
+            return EarthLocation(lat=lat, lon=lon, height=height)
+        return None
 
 
 class CALISTOSpectrogram(GenericSpectrogram):
@@ -27,14 +43,13 @@ class CALISTOSpectrogram(GenericSpectrogram):
     """
 
     def __init__(self, data, meta, **kwargs):
+        if not isinstance(meta, CALISTOMeta):
+            meta = CALISTOMeta(meta)
         super().__init__(meta=meta, data=data, **kwargs)
 
     @property
     def observatory_location(self):
-        lat = self.meta["fits_meta"]["OBS_LAT"] * u.deg * (1.0 if self.meta["fits_meta"]["OBS_LAC"] == "N" else -1.0)
-        lon = self.meta["fits_meta"]["OBS_LON"] * u.deg * (1.0 if self.meta["fits_meta"]["OBS_LOC"] == "E" else -1.0)
-        height = self.meta["fits_meta"]["OBS_ALT"] * u.m
-        return EarthLocation(lat=lat, lon=lon, height=height)
+        return self.meta.observer_location
 
     @classmethod
     def is_datasource_for(cls, data, meta, **kwargs):

radiospectra/spectrogram/sources/waves.py

@@ -1,6 +1,21 @@
+from radiospectra.spectrogram.meta import SpectrogramMeta
 from radiospectra.spectrogram.spectrogrambase import GenericSpectrogram
 
-__all__ = ["WAVESSpectrogram"]
+__all__ = ["WAVESSpectrogram", "WAVESMeta"]
+
+
+class WAVESMeta(SpectrogramMeta):
+    """Metadata for WIND/WAVES spectrograms."""
+
+    @property
+    def background(self):
+        """The background subtracted from the data."""
+        return self.get("background")
+
+    @property
+    def receiver(self):
+        """The name of the receiver."""
+        return self.get("detector")
 
 
 class WAVESSpectrogram(GenericSpectrogram):
@@ -24,21 +39,23 @@ class WAVESSpectrogram(GenericSpectrogram):
     """
 
     def __init__(self, data, meta, **kwargs):
+        if not isinstance(meta, WAVESMeta):
+            meta = WAVESMeta(meta)
         super().__init__(meta=meta, data=data, **kwargs)
 
     @property
     def receiver(self):
         """
         The name of the receiver.
         """
-        return self.meta["receiver"]
+        return getattr(self.meta, "receiver", self.meta.get("receiver"))
 
     @property
     def background(self):
         """
         The background subtracted from the data.
         """
-        return self.meta.bg
+        return getattr(self.meta, "background", self.meta.get("bg"))
 
     @classmethod
     def is_datasource_for(cls, data, meta, **kwargs):

radiospectra/spectrogram/spectrogrambase.py

@@ -5,6 +5,7 @@
 
 from radiospectra.exceptions import SpectraMetaValidationError
 from radiospectra.mixins import NonUniformImagePlotMixin, PcolormeshPlotMixin
+from radiospectra.spectrogram.meta import SpectrogramMeta
 from radiospectra.utils import build_spectrogram_wcs
 
 __all__ = ["GenericSpectrogram"]
@@ -30,6 +31,9 @@ def __init_subclass__(cls, **kwargs):
             cls._registry[cls] = cls.is_datasource_for
 
     def __init__(self, data, meta, wcs=None, **kwargs):
+        if not isinstance(meta, SpectrogramMeta):
+            meta = SpectrogramMeta(meta)
+
         if wcs is None:
             self._validate_meta(meta)
             wcs = build_spectrogram_wcs(self._time_axis_from_meta(meta), meta["freqs"]).wcs
@@ -40,42 +44,45 @@ def observatory(self):
         """
         The name of the observatory which recorded the spectrogram.
         """
-        return self.meta["observatory"].upper()
+        val = getattr(self.meta, "observatory", self.meta.get("observatory"))
+        return val.upper() if val else None
 
     @property
     def instrument(self):
         """
         The name of the instrument which recorded the spectrogram.
         """
-        return self.meta["instrument"].upper()
+        val = getattr(self.meta, "instrument", self.meta.get("instrument"))
+        return val.upper() if val else None
 
     @property
     def detector(self):
         """
         The detector which recorded the spectrogram.
         """
-        return self.meta["detector"].upper()
+        val = getattr(self.meta, "detector", self.meta.get("detector"))
+        return val.upper() if val else None
 
     @property
     def start_time(self):
         """
         The start time of the spectrogram.
         """
-        return self.meta["start_time"]
+        return getattr(self.meta, "date_start", self.meta.get("start_time"))
 
     @property
     def end_time(self):
         """
         The end time of the spectrogram.
         """
-        return self.meta["end_time"]
+        return getattr(self.meta, "date_end", self.meta.get("end_time"))
 
     @property
     def wavelength(self):
         """
         The wavelength range of the spectrogram.
         """
-        return self.meta["wavelength"]
+        return getattr(self.meta, "frequency_range", self.meta.get("wavelength"))
 
     @property
     def times(self):

radiospectra/spectrogram/tests/test_meta.py

@@ -0,0 +1,42 @@
+import pytest
+
+from radiospectra.spectrogram.meta import SpectrogramMeta
+
+
+def test_spectrogram_meta_required_keys():
+    meta = SpectrogramMeta(
+        {
+            "instrument": "test_inst",
+            "observatory": "test_obs",
+            "detector": "test_det",
+            "start_time": "2020-01-01",
+            "end_time": "2020-01-02",
+        }
+    )
+
+    assert meta.instrument == "test_inst"
+    assert meta.observatory == "test_obs"
+    assert meta.detector == "test_det"
+    assert meta.date_start == "2020-01-01"
+    assert meta.date_end == "2020-01-02"
+
+
+def test_spectrogram_meta_missing_required():
+    meta = SpectrogramMeta({})
+    with pytest.raises(KeyError):
+        _ = meta.instrument
+
+
+def test_spectrogram_meta_optional_keys():
+    meta = SpectrogramMeta(
+        {
+            "processing_level": "L2",
+            "version": "1.0",
+            "wavelength": "radio",
+        }
+    )
+
+    assert meta.processing_level == "L2"
+    assert meta.version == "1.0"
+    assert meta.frequency_range == "radio"
+    assert meta.temporal_resolution is None