# pywws - Python software for USB Wireless Weather Stations
# http://github.com/jim-easterbrook/pywws
# Copyright (C) 2008-21 pywws contributors
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
"""Predict future weather using recent data
::
%s
"""
from __future__ import absolute_import, print_function
__docformat__ = "restructuredtext en"
__usage__ = """
usage: python -m pywws.forecast [options] data_dir
options are:
-h | --help display this help
data_dir is the root directory of the weather data
"""
__doc__ %= __usage__
__usage__ = __doc__.split('\n')[0] + __usage__
from ast import literal_eval
from datetime import datetime, timedelta
import getopt
import sys
import pywws.localisation
import pywws.storage
def _(msg):
return msg
_forecast_text = {
'A' : _("Settled fine"),
'B' : _("Fine weather"),
'C' : _("Becoming fine"),
'D' : _("Fine, becoming less settled"),
'E' : _("Fine, possible showers"),
'F' : _("Fairly fine, improving"),
'G' : _("Fairly fine, possible showers early"),
'H' : _("Fairly fine, showery later"),
'I' : _("Showery early, improving"),
'J' : _("Changeable, mending"),
'K' : _("Fairly fine, showers likely"),
'L' : _("Rather unsettled clearing later"),
'M' : _("Unsettled, probably improving"),
'N' : _("Showery, bright intervals"),
'O' : _("Showery, becoming less settled"),
'P' : _("Changeable, some rain"),
'Q' : _("Unsettled, short fine intervals"),
'R' : _("Unsettled, rain later"),
'S' : _("Unsettled, some rain"),
'T' : _("Mostly very unsettled"),
'U' : _("Occasional rain, worsening"),
'V' : _("Rain at times, very unsettled"),
'W' : _("Rain at frequent intervals"),
'X' : _("Rain, very unsettled"),
'Y' : _("Stormy, may improve"),
'Z' : _("Stormy, much rain")
}
del _
[docs]def zambretti_code(params, hourly_data):
"""Simple implementation of Zambretti forecaster algorithm.
Inspired by beteljuice.com Java algorithm, as converted to Python by
honeysucklecottage.me.uk, and further information
from http://www.meteormetrics.com/zambretti.htm"""
north = literal_eval(params.get('Zambretti', 'north', 'True'))
baro_upper = float(params.get('Zambretti', 'baro upper', '1050.0'))
baro_lower = float(params.get('Zambretti', 'baro lower', '950.0'))
if not hourly_data['rel_pressure']:
return ''
if hourly_data['wind_ave'] is None or hourly_data['wind_ave'] < 0.3:
wind = None
else:
wind = hourly_data['wind_dir']
if hourly_data['pressure_trend'] is None:
trend = 0.0
else:
trend = hourly_data['pressure_trend'] / 3.0
# normalise pressure
pressure = 950.0 + (
(1050.0 - 950.0) * (hourly_data['rel_pressure'] - baro_lower) /
(baro_upper - baro_lower))
# adjust pressure for wind direction
if wind is not None:
if not isinstance(wind, int):
wind = int(wind + 0.5) % 16
if not north:
# southern hemisphere, so add 180 degrees
wind = (wind + 8) % 16
pressure += ( 5.2, 4.2, 3.2, 1.05, -1.1, -3.15, -5.2, -8.35,
-11.5, -9.4, -7.3, -5.25, -3.2, -1.15, 0.9, 3.05)[wind]
# compute base forecast from pressure and trend (hPa / hour)
summer = north == (hourly_data['idx'].month >= 4 and
hourly_data['idx'].month <= 9)
if trend >= 0.1:
# rising pressure
if summer:
pressure += 3.2
F = 0.1740 * (1031.40 - pressure)
LUT = ('A', 'B', 'B', 'C', 'F', 'G', 'I', 'J', 'L', 'M', 'M', 'Q', 'T',
'Y')
elif trend <= -0.1:
# falling pressure
if summer:
pressure -= 3.2
F = 0.1553 * (1029.95 - pressure)
LUT = ('B', 'D', 'H', 'O', 'R', 'U', 'V', 'X', 'X', 'Z')
else:
# steady
F = 0.2314 * (1030.81 - pressure)
LUT = ('A', 'B', 'B', 'B', 'E', 'K', 'N', 'N', 'P', 'P', 'S', 'W', 'W',
'X', 'X', 'X', 'Z')
# clip to range of lookup table
F = min(max(int(F + 0.5), 0), len(LUT) - 1)
# convert to letter code
return LUT[F]
[docs]def zambretti(params, hourly_data):
code = zambretti_code(params, hourly_data)
return pywws.localisation.translation.ugettext(_forecast_text[code])
[docs]def main(argv=None):
from pywws.timezone import time_zone
if argv is None:
argv = sys.argv
try:
opts, args = getopt.getopt(argv[1:], "h", ['help'])
except getopt.error as msg:
print('Error: %s\n' % msg, file=sys.stderr)
print(__usage__.strip(), file=sys.stderr)
return 1
# process options
for o, a in opts:
if o in ('-h', '--help'):
print(__usage__.strip())
return 0
# check arguments
if len(args) != 1:
print("Error: 1 argument required", file=sys.stderr)
print(__usage__.strip(), file=sys.stderr)
return 2
data_dir = args[0]
with pywws.storage.pywws_context(data_dir) as context:
params = context.params
pywws.localisation.set_application_language(params)
hourly_data = context.hourly_data
idx = hourly_data.before(datetime.max)
print('Zambretti (current):', zambretti(params, hourly_data[idx]))
idx = time_zone.utc_to_local(idx)
if idx.hour < 8 or (idx.hour == 8 and idx.minute < 30):
idx -= timedelta(hours=24)
idx = idx.replace(hour=9, minute=0, second=0)
idx = time_zone.local_to_utc(idx)
idx = hourly_data.nearest(idx)
lcl = time_zone.utc_to_local(idx)
print('Zambretti (at %s):' % lcl.strftime('%H:%M %Z'), zambretti(
params, hourly_data[idx]))
return 0
if __name__ == "__main__":
sys.exit(main())