Source code for lsst.sims.maf.metrics.optimalM5Metric

from builtins import str
from .baseMetric import BaseMetric
from .simpleMetrics import Coaddm5Metric
import numpy as np
import warnings

__all__ = ['OptimalM5Metric']


[docs]class OptimalM5Metric(BaseMetric): """Compare the co-added depth of the survey to one where all the observations were taken on the meridian. Parameters ---------- m5Col : str ('fiveSigmaDepth') Column name that contains the five-sigma limiting depth of each observation optM5Col : str ('m5Optimal') The column name of the five-sigma-limiting depth if the observation had been taken on the meridian. normalize : bool (False) If False, metric returns how many more observations would need to be taken to reach the optimal depth. If True, the number is normalized by the total number of observations already taken at that position. magDiff : bool (False) If True, metric returns the magnitude difference between the achieved coadded depth and the optimal coadded depth. Returns -------- numpy.array If magDiff is True, returns the magnitude difference between the optimal and actual coadded depth. If normalize is False (default), the result is the number of additional observations (taken at the median depth) the survey needs to catch up to optimal. If normalize is True, the result is divided by the number of observations already taken. So if a 10-year survey returns 20%, it would need to run for 12 years to reach the same depth as a 10-year meridian survey. """ def __init__(self, m5Col='fiveSigmaDepth', optM5Col='m5Optimal', filterCol='filter', magDiff=False, normalize=False, **kwargs): if normalize: self.units = '% behind' else: self.units = 'N visits behind' if magDiff: self.units = 'mags' super(OptimalM5Metric, self).__init__(col=[m5Col, optM5Col,filterCol], units=self.units, **kwargs) self.m5Col = m5Col self.optM5Col = optM5Col self.normalize = normalize self.filterCol = filterCol self.magDiff = magDiff self.coaddRegular = Coaddm5Metric(m5Col=m5Col) self.coaddOptimal = Coaddm5Metric(m5Col=optM5Col)
[docs] def run(self, dataSlice, slicePoint=None): filters = np.unique(dataSlice[self.filterCol]) if np.size(filters) > 1: warnings.warn("OptimalM5Metric does not make sense mixing filters. Currently using filters " + str(filters)) regularDepth = self.coaddRegular.run(dataSlice) optimalDepth = self.coaddOptimal.run(dataSlice) if self.magDiff: return optimalDepth-regularDepth medianSingle = np.median(dataSlice[self.m5Col]) # Number of additional median observations to get as deep as optimal result = (10.**(0.8 * optimalDepth)-10.**(0.8 * regularDepth)) / \ (10.**(0.8 * medianSingle)) if self.normalize: result = result/np.size(dataSlice)*100. return result