loop over array, but not every element

Question

I would like to iterate over the array and getting an average from 5 next elements, not from the whole array. I try to do it by code bellow, but it doesn´t work. I appreciate any kind of help or suggestions.

 function standardDeviation(array) {
        let newArray = [];
        for (let i = 0; i < array.length; i++) {
          let tempArray = []; 
          const arrAvg = tempArray =>
            tempArray.reduce((a, b) => a + b, 0) / tempArray.length;
          newArray += tempArray;

          for (let j = array[i]; (j = array[i + 5]); i++) {
            tempArray += array[j];
          }
        }
        console.log(newArray);
        return newArray;
      }
      var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
      standardDeviation(arr);

I guess you want for(let j = i; j < array.length && j < i + 5; j++) in the inner loop — Jonas Wilms
– Jonas Wilms, Commented Feb 27, 2019 at 14:55

Nina Scholz · Accepted Answer · 2019-02-27 14:58:53Z

2

You could slice a given array and take only five elements for getting an average.

function standardDeviation(array) {
    const arrAvg = tempArray => tempArray.reduce((a, b) => a + b, 0) / tempArray.length;
    return array.map((_, i, a) => arrAvg(a.slice(i, i + 5)));
}

var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(standardDeviation(arr));

answered Feb 27, 2019 at 14:58

Nina Scholz

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Flo · Accepted Answer · 2019-02-27 15:06:05Z

0

You could try using the slice() function of array element.

// simulated loop index
var curr_index_pos = 3; 
// entire array
var array_full = [1,2,3,4,5,6,7,8,9,10]; 

// array with 5 next values from "curr_index_pos"
var array_5 = array_full.slice(curr_index_pos,curr_index_pos+5); 

var sum = 0;
for( var i = 0; i < array_5.length; i++ ) {
   sum += parseInt( array_5[i] ); 
}

var avg = sum/array_5.length;

console.log("array_5", array_5);
// [4,5,6,7,8]
console.log("sum", sum);
// 30
console.log("avg", avg);
// 6

answered Feb 27, 2019 at 15:06

Flo

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