Guide on aggregating values of a specific property within an array of objects, considering a given condition

As a junior Web Developer seeking some guidance to solve a problem, I am reaching out here for the first time. Please bear with me if I miss any crucial details.

The data array I have looks like this:

[
 {x: Date(1234), y: 0}
 {x: Date(1235), y: 0}
 {x: Date(1236), y: 300}
 {x: Date(1237), y: 300}
 {x: Date(1238), y: 300}
 {x: Date(1239), y: 300}
 {x: Date(1240), y: 300}
 {x: Date(1241), y: 0}
 {x: Date(1242), y: 0}
 {x: Date(1243), y: 0}
]

I am looking to create a new array where consecutive 'y' values greater than 0 are summed up. The sum should be associated with the first 'x' value of the consecutive items, as shown below:

[
 {x: Date(1234), y: 0}
 {x: Date(1235), y: 0}
 {x: Date(1236), y: 1500}
 {x: Date(1241), y: 0}
 {x: Date(1242), y: 0}
 {x: Date(1243), y: 0}
]

I believe utilizing 'reduce' could help, but I am unsure about the exact steps to take. Any assistance on this matter would be highly appreciated.

Thank you in advance!

javascriptarraysreduce

Answer №1

To achieve the desired result, you can utilize the reduce method in the following manner: https://jsbin.com/leladakiza/edit?js,console

var data = [
 {x: Date(1234), y: 0},
 {x: Date(1235), y: 0},
 {x: Date(1236), y: 300},
 {x: Date(1237), y: 300},
 {x: Date(1238), y: 300},
 {x: Date(1239), y: 300},
 {x: Date(1240), y: 300},
 {x: Date(1241), y: 0},
 {x: Date(1242), y: 0},
 {x: Date(1243), y: 0},
];

var result = data.reduce(function (accumulator, value) {
  var lastIndex = accumulator.length - 1;
  if (value.y <= 0 || lastIndex < 0 || accumulator[lastIndex].y <= 0) {
    accumulator.push(value);
  } else {
    accumulator[lastIndex].y += value.y;
  }
  return accumulator;
}, []);

Answer №2

One efficient way to handle this scenario is by utilizing a reduce function as shown below.

var arr = [{
    x: Date(1234),
    y: 0
  },
  {
    x: Date(1235),
    y: 0
  },
  {
    x: Date(1236),
    y: 300
  },
  {
    x: Date(1237),
    y: 300
  },
  {
    x: Date(1238),
    y: 300
  },
  {
    x: Date(1239),
    y: 300
  },
  {
    x: Date(1240),
    y: 300
  },
  {
    x: Date(1241),
    y: 0
  },
  {
    x: Date(1242),
    y: 0
  },
  {
    x: Date(1243),
    y: 0
  }
];

var yGreaterThanZero = null;
var aggregated = arr.reduce(function(acc, cur) {
  if (cur.y > 0) {
    if (!yGreaterThanZero) {
      acc.push(cur);
      yGreaterThanZero = cur;
    } else {
      yGreaterThanZero.y += cur.y;
    }
  } else {
    acc.push(cur);
  }
  return acc;
}, []);

console.log(aggregated);

Answer №3

This logic demonstrates an interesting approach. The process involves initiating recording when a value greater than 0 is detected and then concluding it at the end of the recording (when a value less than 0 appears).

var a = [
 {x: Date(1234), y: 0},
 {x: Date(1235), y: 0},
 {x: Date(1236), y: 300},
 {x: Date(1237), y: 300},
 {x: Date(1238), y: 300},
 {x: Date(1239), y: 300},
 {x: Date(1240), y: 300},
 {x: Date(1241), y: 0},
 {x: Date(1242), y: 0},
 {x: Date(1243), y: 0},
 {x: Date(1244), y: 200},
 {x: Date(1245), y: 200},
 {x: Date(1246), y: 200},
 {x: Date(1247), y: 200},
]

var newA = [];
var recording = false;
var temp = {}
a.forEach(item => {
  if (item.y > 0) {
    recording = true;
    if (temp.y) {
      if(!temp.x) temp.x = item.x;
      temp.y = temp.y + item.y
    } else {
      temp = item;
    }
  } else {
    if (recording) newA.push(temp)
    recording = false;
    temp = {};
    newA.push(item);
  }
})
if (recording) newA.push(temp)

console.log(newA)

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