survey.polygon

survey.polygon#

This module defines the PolygonSurvey class, a survey type where fields are represented as shapely polygons projected onto the sky.

class skysurvey.survey.polygon.PolygonSurvey(data=None, fields=None)[source]#

Bases: BaseSurvey

The PolygonSurvey class.

Parameters:

  • data (pandas.DataFrame) – observing data.

  • fields (geopandas.GeoDataFrame) – field definitions.

  • _DEFAULT_FIELDS (geopandas.GeoDataFrame or None) – The default field definitions for this survey type. Subclasses should override this to provide specific survey grids.

classmethod from_pointings(data, footprint=None, moc=None, rakey='ra', deckey='dec')[source]#

Load an instance from pointings.

Parameters:

  • data (pandas.DataFrame or dict) – observing data, must contain the rakey and deckey columns.

  • footprint (shapely.geometry) – footprint in the sky of the observing camera

  • moc (mocpy.MOC) – MOC representation of the observing camera

  • rakey (str) – name of the R.A. column (in deg)

  • deckey (str) – name of the Declination column (in deg)

Return type:

PolygonSurvey

classmethod from_random(size, bands, mjd_range, skynoise_range, fields=None, **kwargs)[source]#

Load an instance with random observing data.

Parameters:

  • size (int) – number of observations to draw

  • bands (list of str) – list of bands that should be drawn.

  • mjd_range (list or array) – min and max mjd for the random drawing.

  • skynoise_range (list or array) – min and max skynoise for the random drawing.

  • fields (geopandas.GeoDataFrame) – field definitions.

  • method (**kwargs goes to the draw_random())

Return type:

PolygonSurvey

get_fields(observed=True)[source]#

Get the fields.

Parameters:

observed (bool) – if True, return only the observed fields.

Return type:

geopandas.GeoDataFrame

get_observed_area(nside=200)[source]#

Measure the observed area.

This uses healpy for accuracy.

Parameters:

nside (int, optional) – Healpix nside.

Returns:

Area in deg2.

Return type:

float

to_healpix(nside, pass_data=True, backend='polars', polars_to_pandas=True, use_pyarrow_extension_array=False)[source]#

Convert the current polygon survey into a healpix survey.

Parameters:

  • nside (int) – Healpix nside.

  • pass_data (bool, optional) – Should the returned survey have the full data of just the fieldid matching?

  • backend (str, optional) –

    Which backend to use to merge the data (speed issue):

    • polars (fastest): requires polars installed -> converted to pandas at the end

    • pandas (classic): the normal way

    • dask (lazy): as persisted dask.dataframe is returned

  • polars_to_pandas (bool, optional) – = ignored if backend != ‘polars’ = Should the dataframe be converted into a pandas.DataFrame or say a polars.DataFrame (using the to_pandas() option).

  • use_pyarrow_extension_array (bool, optional) – = ignored in backend != ‘polars’ or polars_to_pandas is not True = Should the pandas dataframe be based on numpy array (slow to load but faster then) or based on pyarrow array (like in polars) ; faster but numpy.asarray will be used by pandas when need (which will then slow things down).

Return type:

HealpixSurvey

radec_to_fieldid(radec, observed_fields=False)[source]#

Get the fieldid associated to the given coordinates.

Parameters:

  • radec (pandas.DataFrame or 2d array) – Coordinates in degree.

  • observed_fields (bool, optional) – Should this be limited to fields actually observed? This is ignored is self.data is None.

Return type:

pandas.DataFrame

draw_random(size, bands, mjd_range, skynoise_range, gain_range=1, zp_range=25, inplace=False, fieldids=None, **kwargs)[source]#

Draw random observations.

Parameters:

  • size (int) – number of observations to draw

  • bands (list of str) – list of bands that should be drawn.

  • mjd_range (list or array) – min and max mjd for the random drawing.

  • skynoise_range (list or array) – min and max skynoise for the random drawing.

  • gain_range (list or array) – min and max gain for the random drawing.

  • zp_range (list or array) – min and max zp for the random drawing.

  • inplace (bool) – if True, the data are stored in the instance. Otherwise, a new instance is returned.

  • fieldids (list) – list of fieldids to draw from.

  • _draw_random (**kwargs goes to)

Return type:

PolygonSurvey or None

show(stat='size', column=None, title=None, data=None, origin=180, vmin=None, vmax=None, cmap='tab10', autoscale=False, grid=True, **kwargs)[source]#

Show the sky coverage.

Parameters:

  • stat (str, optional) – Statistic to plot.

  • column (str, optional) – Column to use for the statistic.

  • title (str, optional) – Title of the plot.

  • data (pandas.DataFrame, optional) – Data to plot.

  • origin (float, optional) – Origin of the ra coordinates.

  • vmin (float, optional) – Min and max values for the colorbar.

  • vmax (float, optional) – Min and max values for the colorbar.

  • cmap (str, optional) – Colormap to use.

  • autoscale (bool, optional) – If True, autoscale the plot.

  • grid (bool, optional) – If True, show the grid.

  • **kwargs – Goes to matplotlib.collections.PolyCollection.

Return type:

matplotlib.figure

property fieldids#

List of fields id.

property nfields#

Number of fields.