CODEWITHSUNDEEP
javascript
Prosto Trader
Prosto Trader

Reputation: 3527

Find minimum in array of arrays js

I have an array of arrays, each one of them consists of two values - timestamp and price.

[
  [1147651200000, 376.2],
  [1147737600000, 350],
  [1147824000000, 374.5]
]

I need to find date and time in which price was the lowest among all points. What function should I use, pls help.

EDIT:

Thanks everyone! I took tests to to see which function is fastest. Here is how I did it (example with .sort, others are same)

console.time('cycle');
var k = 0;
while (k<10000) {
var input = [
  [1147651200000, 376.2],
  [1147737600000, 350],
  [1147824000000, 374.5]
];

var output = input.sort(function(a,b){
  return a[1] > b[1];
})[0];
k++;
}
console.log(output);
console.timeEnd('cycle'); //36 ms

.map //67 ms
minimum in cycle // 108 ms

Upvotes: 1

Views: 1579

Answers (4)

RazvanDH
RazvanDH

Reputation: 782

Maybe something like this?

var min = arr[0][1];
var timestamp = 0;
for(i in arr) {
    if(arr[i][1] <= min ) {
        min = arr[i][1];
        timestamp = arr[i][0];
    }
}

Upvotes: 0

RichieHindle
RichieHindle

Reputation: 281375

Sorting the array is O(N logN) - if performance with large arrays might be an issue, here's an O(N) solution:

var min = a[0];
for (var i = 1; i < a.length; i++) {
    if (a[i][1] < min[1]) {
        min = a[i];
    }
}

// min is now [1147737600000, 350]

Upvotes: 2

adeneo
adeneo

Reputation: 318182

Get the numbers from the array into a new array, use Math.min to get the lowest, and backtrack to get the timestamp.

var arr = [
  [1147651200000, 376.2],
  [1147737600000, 350],
  [1147824000000, 374.5]
] 

var numbs     = arr.map(function(x) { return x[1]||0 });
var timestamp = arr[numbs.indexOf(Math.min.apply( Math, numbs ))][0];

FIDDLE

Upvotes: 1

hsz
hsz

Reputation: 152206

Just try with:

var input = [
  [1147651200000, 376.2],
  [1147737600000, 350],
  [1147824000000, 374.5]
];

var output = input.sort(function(a,b){
  return a[1] > b[1];
})[0];

Output:

[1147737600000, 350]

Upvotes: 5

Related Questions