Question 392643 in Javascript Question posted in
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Javascript – JS/GAS: Find value pairs matching multiple ratios in array

Google Apps Script:

I have an array with numbers.
The array contains monetary values extracted from an invoice.
Another array contains the applicable VAT/tax values.

For each tax value I want to find the applicable value pair(s) in the array.

Example input:

enter image description here

Resulting Input Arrays:

values = [4000, 2500, 2066.12, 2000, 1834.86];
taxRates = [9,21];

The desired output from these inputs would be:

taxAmounts = [[2000,2500][1834.86, 2066,12]];

indicated in the image above in colors where the numbers in the output came from;

 taxAmounts[0][0] = 2000    = green  = inc tax amount (for taxRates[0])
 taxAmounts[1][0] = 1834.86 = brown  = ex tax amount (for taxRates[0])
 taxAmounts[0][1] = 2500    = yellow = inc tax amount (for taxRates[1])
 taxAmounts[1][1] = 2066,12 = pink   = ex tax amount (for taxRates[1])

in other words I want to find the following values:

inc tax amount for each taxRate in 'taxRates'
ex tax amount for each taxRate in 'taxRates'

My approach:(pseudo code)

Look for 2 items in array which differ by 21%
     when found, check if the highest of these 2 numbers is the highest number in the array
         if highest number --> return this number     //if highest number then only 1 tax bracket
         if not highest number                        //multiple tax brackets
             check for matching value pair for next item in 'taxRates' Array (recursion)
                 if number found in 1st check + number found in 2nd check = highest number in array --> 
                    return these 2 numbers
                 else
                    continue checking for lower % values e.g. 104% until...
                    ...sum of all found values == highest num in array, then return these numbers
                       if no satisfactory match found after all checks
                           return undefined;

I have tried to write this in code but not getting correct output so must have made an error (or likely multiple logic errors in my code which I thus far have not been able to fix). Most likely there is a much smarter way to write this.

Any help will be greatly appreciated. Thank you!

my code:

function findBtwPairs(btwRates, amountsArr, incBtwArr, exBtwArr){
  for(m=0 ; m < btwRates.length ; m++){
    skipIndex = 0;
    for (i=0;i<amountsArr.length;i++){
      for (j=0;j<amountsArr.length;j++){
        if (i!=j){
          cond1 = (roundTo((amountsArr[i]/amountsArr[j]),2) == (1+btwRates[m]/100));
            cond2 = (roundTo((amountsArr[i]/amountsArr[j]),2) == (btwRates[m]/100));
          if (cond1 || cond2){          //inc btw and ex btw specified
              if(cond1){incBtw = amountsArr[i]; exBtw = amountsArr[j];}else{incBtw = amountsArr[i]+amountsArr[j]; exBtw = amountsArr[j];};
            if(roundTo(incBtw,0) == roundTo(amountsArr[0],0)){              //if found amount is highest number
              return [[incBtw], [exBtw]];
            }else{                      //if found amount NOT highest number
                incBtwArr = [incBtw]; exBtw = [exBtw];      //convert to arrays
              functionOutput = findBtwPairs(btwRates, amountsArr, incBtw, exBtw);
              if(functionOutput != undefined){
                incBtwArr = incBtwArr + functionOutput[0]; console.log("functionOutput[0] =" + functionOutput[0]);
                exBtwArr = exBtwArr + functionOutput[1]; console.log("functionOutput[1] =" + functionOutput[0]);
                }           //add found inc. and ex. btw values (e.g. 9% inc/ex value) to 'incBtw' and 'exBtw' Arrays
              if (roundTo(sumArray(incBtwArr),0) == roundTo(amountsArr[0]),0){
                return [incBtwArr, exBtwArr]
                }
              } // end of if/else
            } // end of if(cond1 || cond2){
          } // end of if (i!=j){
        } // end of j loop
      } // end of i loop
    } //end of m loop
    console.log( "BTW RATES NOT FOUND USING RATES IN 'btwRates' Array" );
  } // end of fn 'findBtwPairs'

//$$ Helper functions $$

function sumArray(array){
    return array.reduce(add, 0); // with initial value to avoid when the array is empty
    }

function add(accumulator, a) {
  return accumulator + a;
}

function roundTo(num, decimals) {
  return ( +num.toFixed(decimals));
}
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I have since re-written my code in a better way;

    my new code:

            var valuePairs = [];
var inc; var ex;
var amounts = [ 5000, 2000, 2000, 1834.86, 1652.89, 1000, 961.5385, 15, 12,3,1];
var btwTypes = [21,13,9,4];

function tester(){
  // console.log(roundTo(5000,0));
  console.log("final output = [" + theBtwFinder(btwTypes) + "]");
}

function theBtwFinder(rates){
  while(rates.length>0){
    if (findValuePair(rates[0]) != undefined){
      valuePairs.push(findValuePair(rates[0])[0]); valuePairs.push(findValuePair(rates[0])[1])

      if(roundTo(sumArrayEvenIndices(valuePairs),0) == roundTo(amounts[0],0)){
      return valuePairs;
      }
      }
      btwTypes.shift(); //remove first item of 'btwTypes' Array since we're done checking for that btw percentage
    }
  }

function findValuePair(deltaPercentage){
  for(i=0;i<amounts.length;i++){
    for(j=0;j<amounts.length;j++){
      if(i!=j){ //don't check value against itself
        if ( roundTo(amounts[i]/amounts[j], 2) == (1 + deltaPercentage/100) ){
          inc = amounts[i]; ex = amounts[j];
          return[inc, ex];
        }else if( roundTo(amounts[i]/amounts[j], 2) == (deltaPercentage/100) ){
          inc = amounts[i]+amounts[j]; ex = amounts[j];
          return[inc, ex];
        }
      }
    }
  }
  return undefined; //no pair found
}

// $$$ HELPER FUNCTIONS $$$
function sumArrayEvenIndices(array){
  var sum = 0;
  for(index in array){
    if (!(index % 2)){ //of index is even
      sum += array[index];
    }
  }
    return sum; 
    }

function roundTo(num, decimals) {
  return ( +num.toFixed(decimals));
}

    Visual representation of what the code does:

    function input: enter image description here


  2. 0

    I hope this can help

    function findBtwPairs(taxRates, values) {
    let taxAmounts = [];

    for (let rate of taxRates) {
        let found = false;

        for (let i = 0; i < values.length; i++) {
            for (let j = i + 1; j < values.length; j++) {
                let exTax = values[j];
                let incTax = values[i] - exTax;

                if (Math.abs(incTax / exTax * 100 - rate) < 0.01) {
                    taxAmounts.push([values[i], exTax]);
                    found = true;
                    break;
                }
            }
            if (found) break;
        }
    }
    return taxAmounts;
}

// Example usage:
let values = [4000, 2500, 2066.12, 2000, 1834.86];
let taxRates = [9, 21];
let result = findBtwPairs(taxRates, values);
console.log(result);
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