Android Open Source - humiditytracker Climate Data

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License

The source code is released under:

GNU General Public License

Java Source Code

/*
This file is part of leafdigital Humidity tracker.
//from w w  w.j ava  2  s  .  c o  m
Humidity tracker 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 3 of the License, or
(at your option) any later version.

Humidity tracker 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 Humidity tracker. If not, see <http://www.gnu.org/licenses/>.

Copyright 2010 Samuel Marshall.
*/
package com.leafdigital.humidity;

public class ClimateData
{
  public final static int FIELD_TEMPERATURE=0, FIELD_HUMIDITY=1,
    FIELD_DEWPOINT=2, FIELD_DENSITY=3;

  private double[] measured = new double[4], min = new double[4], max = new double[4];

  public static class FieldValue
  {
    private float measured, min, max;

    private FieldValue(int field, double[] measured, double[] min, double[] max)
    {
      this.measured = (float)measured[field];
      this.min = (float)min[field];
      this.max = (float)max[field];
    }

    public float getMeasured()
    {
      return measured;
    }

    public float getMin()
    {
      return min;
    }

    public float getMax()
    {
      return max;
    }
  }

  public ClimateData(double temp, float tempError, double humidity, float humidityError)
  {
    measured[FIELD_TEMPERATURE] = temp;
    min[FIELD_TEMPERATURE] = Math.max(0, temp - tempError);
    max[FIELD_TEMPERATURE] = Math.min(40, temp + tempError);

    measured[FIELD_HUMIDITY] = humidity;
    min[FIELD_HUMIDITY] = Math.max(1, humidity - humidityError);
    max[FIELD_HUMIDITY] = Math.min(100, humidity + humidityError);

    measured[FIELD_DEWPOINT] = getDewpoint(measured);
    min[FIELD_DEWPOINT] = getDewpoint(min);
    max[FIELD_DEWPOINT] = getDewpoint(max);

    measured[FIELD_DENSITY] = getDensity(measured);
    min[FIELD_DENSITY] = getDensity(min);
    max[FIELD_DENSITY] = getDensity(max);
  }

  private static double getDewpoint(double[] values)
  {
    double temp = values[FIELD_TEMPERATURE];
    double humidity = values[FIELD_HUMIDITY];

    // Dewpoint valid up to 60 degrees, from
    // http://en.wikipedia.org/wiki/Dew_point#Calculating_the_dew_point
    double a = 17.271, b = 237.2;
    double gamma = ((a * temp) / (b + temp)) + Math.log(humidity/100.0);
    return b * gamma / (a - gamma);
  }

  private static double getDensity(double[] values)
  {
    double temp = values[FIELD_TEMPERATURE];
    double humidity = values[FIELD_HUMIDITY];

    // Approximate saturated vapour density valid up to 40 degrees, from
    // http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/relhum.html#c3
    double saturated = 5.018 + 0.32321 * temp + 0.0081847 * temp * temp
      + 0.00031243 * temp * temp * temp;
    return saturated * (humidity / 100.0);
  }

  public FieldValue getField(int field)
  {
    return new FieldValue(field, measured, min, max);
  }
}

Java Source Code List

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