Navigating through designated interval inside js es6 map

Question

Navigating through designated interval inside js es6 map

I am currently working with a JavaScript map structure that is sorted based on time, storing object states.

Map(key:time(inMilli), value: {object attributes})

My goal is to efficiently retrieve a collection of all values within a specific start and end time range from the map without having to iterate over the entire map.

//here is my current approach. However, I would like to avoid comparing against the entire map of times
let map = dataService.getTimeData()//returns map of all objects
let updates = getRange(someTime, someTime);

function getRange(start, stop){
  let foundValues = [];
  //if start is equal to or after end time
  if(start >= stop) return [start];

  //search the map for values within the given range
  for([key,value] of map){
    if(key > start && key < stop) foundValues.push(key)
  }  
  return foundValues;
}

javascript es6-map

Answer 1

Answer №1

function getValuesInRange(start, stop){

    let valuesInRange = [];

    if (start <= stop) return [start];

    for(let [k, v] of myMap.entries()){
        if (k > start && k < stop) {
            valuesInRange.push(k);
        } else {
            return valuesInRange;
        }
    }  
    return valuesInRange;
}

The function above retrieves values within a specified range from a map and stops the iteration once the range is exceeded.

function findValuesWithinRange(start, stop) {

  const entriesArray = Array.from(myMap);

  let valuesInRange = [];
  let currentEntry = entriesArray.shift();

  while (currentEntry[0] > start && currentEntry[0] < stop && entriesArray.length) {
    valuesInRange.push(currentEntry[1]);
    currentEntry = entriesArray.shift();
  }

  return valuesInRange;

}

This implementation using a while loop avoids iterating through all map items and assumes the map is already sorted.

Answer 2

function getValuesInRange(start, stop){

    let valuesInRange = [];

    if (start <= stop) return [start];

    for(let [k, v] of myMap.entries()){
        if (k > start && k < stop) {
            valuesInRange.push(k);
        } else {
            return valuesInRange;
        }
    }  
    return valuesInRange;
}

The function above retrieves values within a specified range from a map and stops the iteration once the range is exceeded.

function findValuesWithinRange(start, stop) {

  const entriesArray = Array.from(myMap);

  let valuesInRange = [];
  let currentEntry = entriesArray.shift();

  while (currentEntry[0] > start && currentEntry[0] < stop && entriesArray.length) {
    valuesInRange.push(currentEntry[1]);
    currentEntry = entriesArray.shift();
  }

  return valuesInRange;

}

This implementation using a while loop avoids iterating through all map items and assumes the map is already sorted.

Answer 3

Answer №2

Utilized the jstreemap library to work with a TreeMap and iterate through their upper and lower bounds functions. This approach proved to be quite straightforward and efficient, definitely worth trying out.

let map = new TreeMap(); // Just emphasizing that this is now a TreeMap
map = dataService.getData();

function getRange(startTime, endTime){
  let from = map.lowerBound(startTime);
  let to = map.upperBound(endTime);
  let it = from; // Initialize to the first value in iterator
  let foundValues = [];

  // Iterates only from the first requested object to the last. Avoids unnecessary searches for values.
  while(!it.equals(to)){
    foundValues.push(it);
    it.next();
  }
  return foundValues;
}

Answer 4

Utilized the jstreemap library to work with a TreeMap and iterate through their upper and lower bounds functions. This approach proved to be quite straightforward and efficient, definitely worth trying out.

let map = new TreeMap(); // Just emphasizing that this is now a TreeMap
map = dataService.getData();

function getRange(startTime, endTime){
  let from = map.lowerBound(startTime);
  let to = map.upperBound(endTime);
  let it = from; // Initialize to the first value in iterator
  let foundValues = [];

  // Iterates only from the first requested object to the last. Avoids unnecessary searches for values.
  while(!it.equals(to)){
    foundValues.push(it);
    it.next();
  }
  return foundValues;
}

Navigating through designated interval inside js es6 map

Answer №1

Answer №2

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