added i2c/humidity

[pyshared.git] / humidity.py

diff --git a/humidity.py b/humidity.py
new file mode 100755 (executable)
index 0000000..9e4d439
--- /dev/null
+++ b/humidity.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+# -*- coding: iso-8859-15 -*-
+
+RS = 8314.3 # J/(kmol*K) universelle Gaskonstante
+MW = 18.016 # kg/kmol Molekulargewicht des Wasserdampfes
+
+# Openweathermap
+STATION=2911298
+API_ID="41ff32c10636d35b4c7a46000cb1a6a1"
+
+import urllib
+import json
+
+# Sättigungsdampfdruck in hPa
+def calc_saturation_vapor_pressure(temp_c):
+       if temp_c >= 0:
+               a = 7.5
+               b = 237.3
+       else:
+               a = 7.6
+               b = 240.7 
+       
+       return 6.1078 * 10**((a*temp_c)/(b+temp_c))
+
+
+# https://www.wetterochs.de/wetter/feuchte.html
+def calc_humidity_abs(temp_c, humdity_rel):
+       temp_k = temp_c + 273.15
+
+       # Dampfdruck in hPa
+       SDD = calc_saturation_vapor_pressure(temp_c)
+       DD = humdity_rel/100.0 * SDD
+       humidity_abs = 10**5 * MW/RS * DD/temp_k
+       return humidity_abs
+
+
+def calc_humidity_rel(temp_c, humidity_abs):
+       temp_k = temp_c + 273.15
+       SDD = calc_saturation_vapor_pressure(temp_c)
+       DD = humidity_abs*temp_k * RS / (10**5*MW)
+       
+       humdity_rel = DD/SDD*100
+       return humdity_rel
+
+def get_weather_current():
+       query = urllib.urlencode({'id': STATION, 'APPID': API_ID, 'lang': 'de'})
+       url = "http://api.openweathermap.org/data/2.5/weather?units=metric&%s" % query
+       response = urllib.urlopen(url)
+       results = response.read()
+       return json.loads(results)
+
+def check_ventilate(temp_indoor, humdity_rel_indoor):
+       dWeatherCurrent = get_weather_current()
+       temp_outdoor = dWeatherCurrent["main"]["temp"]
+       humdity_rel_outdoor = dWeatherCurrent["main"]["humidity"]
+
+       humdity_abs_indoor = calc_humidity_abs(temp_indoor, humdity_rel_indoor)
+       humdity_abs_outdoor = calc_humidity_abs(temp_outdoor, humdity_rel_outdoor)
+
+       print "Wassergehalt Innen: %.2f, Außen: %.2f" % (humdity_abs_indoor, humdity_abs_outdoor)
+       return humdity_abs_indoor - humdity_abs_outdoor
+
+
+if __name__ == "__main__":
+       check_ventilate(21, 50)