Moving average calculation

gistfile1.js

      // Calculate moving average
      var averageData = [];
      var lastValue = null;
      var movingAverage = null;
      for (var i = 0; i < dates.length; i++) {
        var value = measurementData[i] || missingData[i];
        if (!movingAverage) {
          movingAverage = value;
        } else {
          movingAverage = ((value - movingAverage)/7) + movingAverage;
        }
        if (isNaN(movingAverage)) {
          averageData.push(null);
        } else {
          averageData.push(movingAverage);
        }
      }
      // Calculate trend if there is more than 3 data points
      var oldestAverage = null;
      var numAveragePoints = 0;
      ED.util.each(dates, function(date, dateIndex) {
        if (averageData[dateIndex] && !oldestAverage) {
          oldestAverage = averageData[dateIndex];
        }
        if (averageData[dateIndex]) {
          numAveragePoints++;
          newestAverage = averageData[dateIndex];
        }
      });

      var averageChange = null;
      if (numAveragePoints > 3) {
        averageChange = (newestAverage - oldestAverage)/numAveragePoints;
      }