CODEWITHSUNDEEP
javascriptarraysmultidimensional-array
beriliox
beriliox

Reputation: 267

How to get the minimum value from a multi-dimensional array?

I'm trying to get the lower numeric value from a multi-dimensional array. Just like this.

var Things = [
    ["guitar", "99", "guitar.png"],
    ["vinyl", "89", "vinyl.png"],
    ["bed", "25", "bed.png"]
];

I would like to return an alert of the lower value, like this:

alert() // 25

If anybody could help me, would be very grateful.

Upvotes: 0

Views: 186

Answers (4)

Spencer Wieczorek
Spencer Wieczorek

Reputation: 21565

Assuming the second elements are the values we are comparing. We can simply do a standard algorithm to iterate through an array and find the lowest value.

var array = [
  ["guitar", "99", "guitar.png"],
  ["vinyl", "89", "vinyl.png"],
  ["bed", "25", "bed.png"]
];
// Assume the first element has the lowest value     
var lowest = +Infinity; // `+` cast to number                       
array.forEach(function(item) {
    if(+item[1] < lowest) lowest = +item[1]; // If we find a lower value update lowest
});
console.log(lowest);

Upvotes: 0

user663031
user663031

Reputation:

Decompose the problem into two parts you can solve separately (or use existing tools to solve):

  1. Extract the second element of each sub-array--into a new, one-level array.
  2. Find the minimum of an array.

For the first, we use map to create a new array from an old one, by applying some transformation to each element. In this case, the transformation is to extract the second element, and convert it to a number, so:

Things.map(([,num]) => +num))

[,num] means to assign the second element of the array passed in to the parameter num), and the the plus sign makes sure it's a number. See below for the non-ES6 version.

For the second, we can just use Math.min.

Combining these, we can write:

Math.min(...Things.map(([,num]) => +num)))

Math.min(...) passes all the elements in the mapped array (the numbers) as parameters to Math.min.

Obligatory disclaimer: the => is the ES6 arrow function, the [,num] is ES6 parameter destructuring (, and ... is the ES6 parameter spread operator. These will work only in environments that support ES6 one way or another. Otherwise, fall back to 

Math.min.apply(0, Things.map(function(elt) { return +elt[1]; }))

Upvotes: 1

Amadan
Amadan

Reputation: 198304

var array = [
        ["guitar", "99", "guitar.png"],
        ["vinyl", "89", "vinyl.png"],
        ["bed", "25", "bed.png"]
    ];

min_second = array.reduce(function(a, x) {
  var b = parseFloat(x[1]);
  return a < b ? a : b;
}, Number.POSITIVE_INFINITY);
              
console.log(min_second);

array.reduce will apply the callback function to the accumulator and each consecutive element, and assign the result to the accumulator; the accumulator starts at +∞. The intent of the callback is that each element whose second value (converted to a number) is less than that becomes the new accumulator. Thus,

  • the accumulator starts at +∞
  • when compared to 99, becomes 99
  • when compared to 89, becomes 89
  • when compared to 25, becomes 25

If it were to be compared to a value greater than the current value of the accumulator, it would not change.

Upvotes: 1

toto
toto

Reputation: 1190

Try it using sort function:

function compare(a,b) {
  if (parseInt(a[1]) < parseInt(b[1]))
    return -1;
  if (parseInt(a[1]) > parseInt(b[1]))
    return 1;
  return 0;
}

var myArray = [
        ["guitar", "99", "guitar.png"],
        ["vinyl", "89", "vinyl.png"],
        ["bed", "25", "bed.png"]
    ];

myArray.sort(compare);

alert(myArray[0][1]);

Upvotes: -1

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