Find the nearest value in an array

Question

Find the nearest value in an array

I need to find the closest number in an array that is not higher than a specified number. Here's an example scenario:
Let's say we have an array:

[1, 3, 7, 15, 40, 55, 70, 80, 95]

The variable for the number is: numberD1;
If numberD1 is 8 - The closest number should be 7, not 15.
If numberD1 is 54 - The closest number should be 40, not 55.

In other words, I want to find the closest number in the array that is not greater than the selected number (similar to the Math.floor() function).

I apologize for any grammar errors in my English. I hope I have explained my issue clearly.

javascript arrays

Answer 1

Answer №1

If you're looking for a solution, consider this code snippet:

// Here is a sample array for demonstration
let numbers = [1, 3, 7, 15, 40, 55, 70, 80, 95];

// Finding the closest number in the array
function getClosestNumber(numbers, target) {
    return target - numbers.reduce(function(currentClosest, value) {
        return target >= value ? Math.min(target - value, currentClosest) : currentClosest;
    }, 1e100);
}  

// Outputting the results
document.write('Closest number to 8 is: ' + getClosestNumber(numbers, 8));

document.write('<br>');

document.write('Closest number to 54 is: ' + getClosestNumber(numbers, 54));

Answer 2

If you're looking for a solution, consider this code snippet:

// Here is a sample array for demonstration
let numbers = [1, 3, 7, 15, 40, 55, 70, 80, 95];

// Finding the closest number in the array
function getClosestNumber(numbers, target) {
    return target - numbers.reduce(function(currentClosest, value) {
        return target >= value ? Math.min(target - value, currentClosest) : currentClosest;
    }, 1e100);
}  

// Outputting the results
document.write('Closest number to 8 is: ' + getClosestNumber(numbers, 8));

document.write('<br>');

document.write('Closest number to 54 is: ' + getClosestNumber(numbers, 54));

Answer 3

Answer №2

Based on my understanding, it seems that you are in search of a solution similar to this one, especially when the array is organized in ascending order:

let myList = ...
let targetNumber = ...
let finalResult = null;
for (let index = 0; index < myList.length(); index++){
    if (myList[index] <= targetNumber)
        targetNumber = myList[index];
}
return finalResult;

Answer 4

Based on my understanding, it seems that you are in search of a solution similar to this one, especially when the array is organized in ascending order:

let myList = ...
let targetNumber = ...
let finalResult = null;
for (let index = 0; index < myList.length(); index++){
    if (myList[index] <= targetNumber)
        targetNumber = myList[index];
}
return finalResult;

Answer 5

Answer №3

If your array is already sorted, you can simply search for the specified value and return the value right before it.

Loop through the array with a search, then return numberD1[key - 1];

Oh, I see that you are looking for any random value, but I believe you can still find a solution. Look for the nearest value greater than it and apply the same logic I mentioned before.

Answer 6

If your array is already sorted, you can simply search for the specified value and return the value right before it.

Loop through the array with a search, then return numberD1[key - 1];

Oh, I see that you are looking for any random value, but I believe you can still find a solution. Look for the nearest value greater than it and apply the same logic I mentioned before.

Answer 7

Answer №4

Here is a solution that should meet the requirements:

Updated - Implemented logic to find a number that is closest but lower if possible

function findClosestLower(num, array){
var closest = Infinity
    for (var i = 0; i < array.length; i++)
        if (closest < num){
            if (array[i] < num && array[i] > closest)
                closest = array[i]
        }
        else if (array[i] < num || array[i] < closest)
            closest = array[i]
    return closest != Infinity? closest :null
}

Answer 8

Here is a solution that should meet the requirements:

Updated - Implemented logic to find a number that is closest but lower if possible

function findClosestLower(num, array){
var closest = Infinity
    for (var i = 0; i < array.length; i++)
        if (closest < num){
            if (array[i] < num && array[i] > closest)
                closest = array[i]
        }
        else if (array[i] < num || array[i] < closest)
            closest = array[i]
    return closest != Infinity? closest :null
}

Answer 9

Answer №5

I had this idea to create a custom method called Array.prototype.insert() that would add a series of items at a specified index in an array and return the updated array. This method is essential for functional JavaScript programming. However, the insertNum function mentioned in the context of this discussion does not alter the original array.

Array.prototype.insert = function(i,...rest) {
  this.splice(i,0,...rest)
  return this
}

var arr = [1, 3, 7, 15, 40, 55, 70, 80, 95];
var insertNum = (a,n) => a.slice(0)
                          .insert(a.reduce((p,c,i) => {var d = Math.abs(n-c);
                                                       p[0] > d && (p[0] = d, p[1] = n > c ? i+1 : i);
                                                       return p} ,[Infinity,0])[1],n);

document.writeln("<pre>" + JSON.stringify(insertNum(arr,8)) + "</pre>");
document.writeln("<pre>" + JSON.stringify(insertNum(arr,54)) + "</pre>");

Answer 10

I had this idea to create a custom method called Array.prototype.insert() that would add a series of items at a specified index in an array and return the updated array. This method is essential for functional JavaScript programming. However, the insertNum function mentioned in the context of this discussion does not alter the original array.

Array.prototype.insert = function(i,...rest) {
  this.splice(i,0,...rest)
  return this
}

var arr = [1, 3, 7, 15, 40, 55, 70, 80, 95];
var insertNum = (a,n) => a.slice(0)
                          .insert(a.reduce((p,c,i) => {var d = Math.abs(n-c);
                                                       p[0] > d && (p[0] = d, p[1] = n > c ? i+1 : i);
                                                       return p} ,[Infinity,0])[1],n);

document.writeln("<pre>" + JSON.stringify(insertNum(arr,8)) + "</pre>");
document.writeln("<pre>" + JSON.stringify(insertNum(arr,54)) + "</pre>");

Find the nearest value in an array

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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