import os
import numpy as np
from jwst import datamodels
from jwst.stpipe import Step
[docs]class GetDefaultGain(Step):
""" Get the default gain. """
spec = """
median_value = boolean(default=False) # only return median value.
save = boolean(default=False) # save gain model to disk as .fits.
save_path = string(default=None) # save gain model path.
"""
[docs] def process(self, input):
""" Get and save gain data from the default CRDS files.
Parameters
----------
input: jwst.datamodels.RampModel or jwst.datamodels.CubeModel
This is either an uncal.fits or rateints.fits loaded
data segment. The gain will be the same no matter which
data segment you pass in.
median_value : boolean
If True only return the median value rather than the gain
model. Default is False.
save : boolean
If True save the gain model to disc. Default is False.
save_path : string
If save==True save the gain model to this path. Default
is None.
Returns
-------
if median_value == False:
gain : jwst.datamodels.GainModel
The gain model which can be passed to other steps.
elif median_value == True:
gain : float
The median gain value on the entire detector.
"""
with datamodels.open(input) as input_model:
# Check input model type.
if not isinstance(input_model, datamodels.RampModel) \
and not isinstance(input_model, datamodels.CubeModel):
self.log.error("Input is a {} which was not expected for "
"GainStep, skipping step.".format(
str(type(input_model))))
return input_model
# Extract default gain model.
self.log.info("Getting default gain model.")
gain_filename = self.get_reference_file(input_model, "gain")
gain_model = datamodels.GainModel(gain_filename)
if self.save:
gain_model.save(path=os.path.join(
self.save_path, "default_gain.fits"))
# Median value.
med_gain = np.median(gain_model.data)
self.log.info("Median gain={} electrons/DN.".format(med_gain))
if self.median_value:
return float(med_gain)
else:
return gain_model
def finalize_result(self, res, ref):
"""
:meta private:
"""
# Required to enable ref model to be returned.
# Overwrites base class method.
pass