CODEWITHSUNDEEP
javascriptmathrange
8DK
8DK

Reputation: 714

Math.min/max.apply set values as percent of new range

I have an array list of values

var v=[0.009865,0.009866,0.009309,0.009831,0.009919,0.009965,0.009806,0.009509,0.009731,0.009888];

I calculate the min,max and difference between the two to make the range

var max=Math.max.apply(this,v)/100;
var min=Math.min.apply(this,v)/100;
var dif=max-min;

console.dir({'max':max,'min':min,'dif':dif});

the console.dir shows

max: 0.00009965
min: 0.00009308999999999999
dif: 0.000006560000000000005

Then I loop through each value attempting to convert them into percentages inside the range

(by finding out how larger the current value is than the min, dividing the answer by the dif and multiplying the result by 100 to get the percent)

for (var i=0;i<v.length;i++){
    v[i]=((v[i]-min)/dif)*100;
    console.log(v[i]);
    }

the console.log shows values I really don't expect to see (expected between 0-100)

148962.04268292672
148977.28658536574
140486.43292682915
148443.74999999985
149785.21341463405
150486.43292682915
148062.65243902427
143535.21341463405
146919.35975609746
149312.65243902427

What am I doing wrong?

My reference to the math: https://math.stackexchange.com/questions/51509/how-to-calculate-percentage-of-value-inside-arbitrary-range

Upvotes: 1

Views: 1207

Answers (2)

KooiInc
KooiInc

Reputation: 122916

You could to this using Array.map, something like:

var v= [0.009865,0.009866,0.009309,0.009831,0.009919,0.009965,
        0.009806,0.009509,0.009731,0.009888]
   ,vv= v.map( function (a) { 
                return ( ( Math.abs(a-this.min) / this.diff() )*100 )
                        .toFixed(2); 
               },
               {min: Math.min.apply(null, v), 
                max: Math.max.apply(null, v),
                diff: function () { return this.max-this.min; } }
              );
 // => returns vv
 // ["84.76", "84.91", "0.00", "79.57", "92.99", "100.00", 
 //  "75.76", "30.49", "64.33", "88.26"]

MDN documentation on Array.prototype.map

Upvotes: 0

Barmar
Barmar

Reputation: 781096

Don't divide by 100 when setting max and min:

var max=Math.max.apply(this,v);
var min=Math.min.apply(this,v);

Output:

84.7560975609757
84.90853658536585
0
79.57317073170726
92.9878048780489
100
75.76219512195132
30.487804878048845
64.32926829268297
88.26219512195112

Upvotes: 5

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