# remove datasets with no observations during the requested period
observations = [v for v in data if v is not None]
if len(observations) > 0:
# add the data to the dictionary
evaporation[v['name']] = data
print('')
# the ETCalculator class uses the Penman-Monteith Equation to estimate
# evapotranspiration time series; let's make an instance to use
calculator = ETCalculator()
# the ETCalculator makes use of hourly and daily time series that must be
# supplied externally as:
#
# 1. time series type (temperature, dewpoint, humidity, wind, solar, etc)
# 2. time step step ("daily", "hourly", or size in minutes, e.g., 60, 1440)
# 3. start time
# 4. list of data values
#
# note these are the same formats used by the PyHSPF HSPFModel class
# so now we can add the daily timeseries from above
calculator.add_timeseries('tmin', 'daily', start, tmin)
calculator.add_timeseries('tmax', 'daily', start, tmax)
calculator.add_timeseries('dewpoint', 'daily', start, dewt)
