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Calcul de la médiane - javascript

J'ai essayé de calculer médiane mais j'ai néanmoins quelques problèmes mathématiques, car je ne peux pas obtenir la valeur médiane correcte ni comprendre pourquoi. Voici le code;

class StatsCollector {

    constructor() {
        this.inputNumber = 0;
        this.average = 0;

        this.timeout = 19000;

        this.frequencies = new Map();
        for (let i of Array(this.timeout).keys()) {
            this.frequencies.set(i, 0);
        }
    }

    pushValue(responseTimeMs) {
        let req = responseTimeMs;
        if (req > this.timeout) {
            req = this.timeout;
        }

        this.average = (this.average * this.inputNumber + req) / (this.inputNumber + 1);

        console.log(responseTimeMs / 1000)
        let groupIndex = Math.floor(responseTimeMs / 1000);
        this.frequencies.set(groupIndex, this.frequencies.get(groupIndex) + 1);

        this.inputNumber += 1;
    }

    getMedian() {
        let medianElement = 0;
        if (this.inputNumber <= 0) {
            return 0;
        }
        if (this.inputNumber == 1) {
            return this.average
        }
        if (this.inputNumber == 2) {
            return this.average
        }
        if (this.inputNumber > 2) {
            medianElement = this.inputNumber / 2;
        }

        let minCumulativeFreq = 0;
        let maxCumulativeFreq = 0;
        let cumulativeFreq = 0;
        let freqGroup = 0;
        for (let i of Array(20).keys()) {
            if (medianElement <= cumulativeFreq + this.frequencies.get(i)) {
                minCumulativeFreq = cumulativeFreq;
                maxCumulativeFreq = cumulativeFreq + this.frequencies.get(i);
                freqGroup = i;
                break;
            }
            cumulativeFreq += this.frequencies.get(i);
        }

        return (((medianElement - minCumulativeFreq) / (maxCumulativeFreq - minCumulativeFreq)) + (freqGroup)) * 1000;
    }

    getAverage() {
        return this.average;
    }

}

Voici l'instantané des résultats lorsque j'entre les valeurs de 

342,654,987,1093,2234,6243,7087,20123

enter image description here

Le résultat correct devrait être;

Médiane: 1663,5

javascriptmedian
8
Muhammed Bayram

Changez votre méthode médiane en ceci: 

function median(values){
    values.sort(function(a,b){
    return a-b;
  });

  if(values.length ===0) return 0

  var half = Math.floor(values.length / 2);

  if (values.length % 2)
    return values[half];
  else
    return (values[half - 1] + values[half]) / 2.0;
}

violon

13
jdmdevdotnet

Voici une autre solution:

function median(numbers) {
    const sorted = numbers.slice().sort();
    const middle = Math.floor(sorted.length / 2);

    if (sorted.length % 2 === 0) {
        return (sorted[middle - 1] + sorted[middle]) / 2;
    }

    return sorted[middle];
}
1
JBallin

`

var arr = {  
  max: function(array) {
    return Math.max.apply(null, array);
  },

  min: function(array) {
    return Math.min.apply(null, array);
  },

  range: function(array) {
    return arr.max(array) - arr.min(array);
  },

  midrange: function(array) {
    return arr.range(array) / 2;
  },

  sum: function(array) {
    var num = 0;
    for (var i = 0, l = array.length; i < l; i++) num += array[i];
    return num;
  },

  mean: function(array) {
    return arr.sum(array) / array.length;
  },

  median: function(array) {
    array.sort(function(a, b) {
      return a - b;
    });
    var mid = array.length / 2;
    return mid % 1 ? array[mid - 0.5] : (array[mid - 1] + array[mid]) / 2;
  },

  modes: function(array) {
    if (!array.length) return [];
    var modeMap = {},
      maxCount = 1,
      modes = [array[0]];

    array.forEach(function(val) {
      if (!modeMap[val]) modeMap[val] = 1;
      else modeMap[val]++;

      if (modeMap[val] > maxCount) {
        modes = [val];
        maxCount = modeMap[val];
      }
      else if (modeMap[val] === maxCount) {
        modes.Push(val);
        maxCount = modeMap[val];
      }
    });
    return modes;
  },

  variance: function(array) {
    var mean = arr.mean(array);
    return arr.mean(array.map(function(num) {
      return Math.pow(num - mean, 2);
    }));
  },

  standardDeviation: function(array) {
    return Math.sqrt(arr.variance(array));
  },

  meanAbsoluteDeviation: function(array) {
    var mean = arr.mean(array);
    return arr.mean(array.map(function(num) {
      return Math.abs(num - mean);
    }));
  },

  zScores: function(array) {
    var mean = arr.mean(array);
    var standardDeviation = arr.standardDeviation(array);
    return array.map(function(num) {
      return (num - mean) / standardDeviation;
    });
  }
};

`

0
Dps