Here is a summary of the current implementation of selector actions in faro as related to this ticket.
Problem we were trying to solve:
Imagine that we have an object catalog for a given tract and we want to compute one metric value per band. We iterate over bands and for each band, we want to load the columns specific for that band that are specified in the selector actions (e.g., load g_psfFlux in order to apply a SNR selection for the g band to get bright stars).
Selector definitions are located in https://github.com/lsst/faro/blob/main/python/lsst/faro/utils/selectors.py ; see for example SNRSelector
For an example of how selectors are used to identify which columns to load from objectTable_tract, see https://github.com/lsst/faro/blob/main/python/lsst/faro/measurement/TractTableMeasurement.py, in particular, the runQuantum method of TractTableMeasurementTask
def runQuantum(self, butlerQC, inputRefs, outputRefs):
|
inputs = butlerQC.get(inputRefs)
|
kwargs = {"currentBands": butlerQC.quantum.dataId['band']}
|
|
columns = list(self.config.measure.columns.values())
|
for column in self.config.measure.columnsBand.values():
|
columns.append(kwargs["currentBands"] + '_' + column)
|
columnsWithSelectors = self._getTableColumnsSelectors(columns, kwargs["currentBands"])
|
kwargs["catalog"] = inputs["catalog"].get(parameters={"columns": columnsWithSelectors})
|
The _getTableColumnsSelectors function is defined in https://github.com/lsst/faro/blob/main/python/lsst/faro/base/CatalogMeasurementBase.py in the CatalogMeasurementBaseTask
def _getTableColumnsSelectors(self, columns, currentBands=None):
|
"""given a list of selectors return columns required to apply these
|
selectors.
|
Parameters
|
----------
|
columns: `list` [`str`]
|
a list of columns required to calculate a metric. This list
|
is appended with any addditional columns required for the selectorActions.
|
currentBands: `list` [`str`]
|
The filter band(s) associated with the observations.
|
Returns
|
-------
|
columnNames: `list` [`str`] the set of columns required to compute a
|
metric with any addditional columns required for the selectorActions
|
appended to the set.
|
"""
|
columnNames = set(columns)
|
for actionStruct in [self.config.measure.selectorActions]:
|
for action in actionStruct:
|
for col in action.columns(currentBands):
|
columnNames.add(col)
|
|
return columnNames
|
The critical line of code above is the following:
action.columns(currentBands)
where we pass in the relevant band or bands to the selector action in order to return the list of columns corresponding to those bands. For example, for the SNRSelector
def columns(self, currentBands=None):
|
allCols = []
|
if self.selectorBandType == "staticBandSet":
|
bands = self.staticBandSet
|
else:
|
bands = currentBands
|
|
if bands is not None:
|
for band in bands:
|
allCols += [band+'_'+self.fluxType, band+'_'+self.fluxType+'Err']
|
else:
|
allCols = [self.fluxType, self.fluxType+'Err']
|
return allCols
|
As I understand it, the difference in implementation of selector actions for analysis_drp https://github.com/lsst/analysis_drp/blob/main/python/lsst/analysis/drp/dataSelectors.py is that the bands are not updated in run time, but are set in advance in configuration.
Story
Here is a summary of the current implementation of selector actions in faro as related to this ticket.
Problem we were trying to solve:
Imagine that we have an object catalog for a given tract and we want to compute one metric value per band. We iterate over bands and for each band, we want to load the columns specific for that band that are specified in the selector actions (e.g., load g_psfFlux in order to apply a SNR selection for the g band to get bright stars).
Selector definitions are located in https://github.com/lsst/faro/blob/main/python/lsst/faro/utils/selectors.py ; see for example SNRSelector
For an example of how selectors are used to identify which columns to load from objectTable_tract, see https://github.com/lsst/faro/blob/main/python/lsst/faro/measurement/TractTableMeasurement.py, in particular, the runQuantum method of TractTableMeasurementTask
The _getTableColumnsSelectors function is defined in https://github.com/lsst/faro/blob/main/python/lsst/faro/base/CatalogMeasurementBase.py in the CatalogMeasurementBaseTask
selectors.ParametersReturns"""columnNames.add(col)The critical line of code above is the following:
action.columns(currentBands)
where we pass in the relevant band or bands to the selector action in order to return the list of columns corresponding to those bands. For example, for the SNRSelector
As I understand it, the difference in implementation of selector actions for analysis_drp https://github.com/lsst/analysis_drp/blob/main/python/lsst/analysis/drp/dataSelectors.py is that the bands are not updated in run time, but are set in advance in configuration.