#!/usr/bin/env python
"""
Save as file calculate-daily-tp.py and run "python calculate-daily-tp.py".
Input file : tp_20170101-20170102.nc
Output file: daily-tp_20170101.nc
"""
import time, sys
from datetime import datetime, timedelta
from netCDF4 import Dataset, date2num, num2date
import numpy as np
day = 20170101
d = datetime.strptime(str(day), '%Y%m%d')
f_in = 'tp_%d-%s.nc' % (day, (d + timedelta(days = 1)).strftime('%Y%m%d'))
f_out = 'daily-tp_%d.nc' % day
time_needed = []
for i in range(1, 25):
time_needed.append(d + timedelta(hours = i))
with Dataset(f_in) as ds_src:
var_time = ds_src.variables['time']
time_avail = num2date(var_time[:], var_time.units,
calendar = var_time.calendar)
indices = []
for tm in time_needed:
a = np.where(time_avail == tm)[0]
if len(a) == 0:
sys.stderr.write('Error: precipitation data is missing/incomplete - %s!\n'
% tm.strftime('%Y%m%d %H:%M:%S'))
sys.exit(200)
else:
print('Found %s' % tm.strftime('%Y%m%d %H:%M:%S'))
indices.append(a[0])
var_tp = ds_src.variables['tp']
tp_values_set = False
for idx in indices:
if not tp_values_set:
data = var_tp[idx, :, :]
tp_values_set = True
else:
data += var_tp[idx, :, :]
with Dataset(f_out, mode = 'w', format = 'NETCDF3_64BIT_OFFSET') as ds_dest:
# Dimensions
for name in ['latitude', 'longitude']:
dim_src = ds_src.dimensions[name]
ds_dest.createDimension(name, dim_src.size)
var_src = ds_src.variables[name]
var_dest = ds_dest.createVariable(name, var_src.datatype, (name,))
var_dest[:] = var_src[:]
var_dest.setncattr('units', var_src.units)
var_dest.setncattr('long_name', var_src.long_name)
ds_dest.createDimension('time', None)
var = ds_dest.createVariable('time', np.int32, ('time',))
time_units = 'hours since 1900-01-01 00:00:00'
time_cal = 'gregorian'
var[:] = date2num([d], units = time_units, calendar = time_cal)
var.setncattr('units', time_units)
var.setncattr('long_name', 'time')
var.setncattr('calendar', time_cal)
# Variables
var = ds_dest.createVariable(var_tp.name, np.double, var_tp.dimensions)
var[0, :, :] = data
var.setncattr('units', var_tp.units)
var.setncattr('long_name', var_tp.long_name)
# Attributes
ds_dest.setncattr('Conventions', 'CF-1.6')
ds_dest.setncattr('history', '%s %s'
% (datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
' '.join(time.tzname)))
print('Done! Daily total precipitation saved in %s' % f_out)
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