Retrieve specific elements from an array based on the other elements present in the array

Question

Retrieve specific elements from an array based on the other elements present in the array

I am working with a result set that consists of various combinations from the following data structure:

[ ["1st", "FELONY"], ["2nd", "FELONY"],  ["3rd", "FELONY"], ["1st", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"]]

For example, it could be:

[  ["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]]

Or:

[ ["1st", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"]]

Or any other combination and order of elements.

If the array contains a subarray with FELONY, my aim is to disregard MISDEMEANOR elements and retrieve "1st" if available, then "2nd", finally "3rd". If there are no FELONY elements in the array, I want to fetch the "1st" MISDEMEANOR element if present, then "2nd", finally "3rd".

This is how I have approached the problem:

var arr = [ ["1st", "FELONY"], ["3rd", "FELONY"], ["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]];
for(var i = 0, found = [], fel1 = false, fel2 = false, fel3 = false, mis1 = false, mis2 = false, mis3 = false; i < arr.length; i++) {
   if(arr[i][0] == "1st" && arr[i][1] == "FELONY"){
       found = arr[i];
       fel1 = true;
   } else if (arr[i][0] == "2nd" && arr[i][1] == "FELONY" && !fel1){
       found = arr[i];
       fel2 = true;
   } else if (arr[i][0] == "3rd" && arr[i][1] == "FELONY" && !fel1 && !fel2){
       found = arr[i];
       fel3 = true;
   } else if (arr[i][0] == "1st" && arr[i][1] == "MISDEMEANOR" && !fel1 && !fel2 && !fel3){
       found = arr[i];
       mis1 = true;
   } else if (arr[i][0] == "2nd" && arr[i][1] == "MISDEMEANOR" && !fel1 && !fel2 && !fel3 && !mis1){
       found = arr[i];
       mis2 = true;
   } else if (arr[i][0] == "3rd" && arr[i][1] == "MISDEMEANOR" && !fel1 && !fel2 && !fel3 && !mis1){
       found = arr[i];
       mis3 = true;
   }
}

if( match && (match[2] == "FELONY" || match[2] == "MISDEMEANOR") && (found[2] != "FELONY" && found[1] != "1st") ) {
            found = [ match[1], match[2], match[3], match[4] ]
            console.log("FOUND! " + found[1]);
} else {
            console.log(`could not parse ${chargesList[i]}`);
}

console.log(JSON.stringify(found));

The current solution works but seems a bit messy. Are there cleaner ways to achieve this using EcmaScript 6 features?

javascript arrays algorithm data-structures ecmascript-6

Answer 1

Answer №1

To efficiently navigate through your array with minimal repetition, it is best to avoid long chains of if/else statements. One effective approach is to implement a scoring system where each item is assigned a unique score and the highest score indicates the desired item. There are numerous ways to achieve this, but one straightforward method involves assigning numerical values to 'felony' and 'misdemeanor' such that they are higher than any other categories. The 10s place represent felony/misdemeanors, while the 1s digit represents the ranking within those categories. By iterating through the array once using this scoring system, you can easily identify the item with the highest score:

let scores = {
  FELONY: 20,
  MISDEMEANOR: 10,
  '1st': 3,
  '2nd': 2,
  '3rd': 1
}

let arr = [["2nd", "FELONY"],["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"],["1st", "FELONY"]]

let highest = 0, result
for (item of arr) {
  let score = item.reduce((a, c) => a + scores[c], 0)
  if (score > highest) {
    highest = score
    result = item
  }
}
console.log(result)

This method also facilitates easy modifications to preferences or the addition of new categories without relying on alphabetical order for sorting.

Answer 2

To efficiently navigate through your array with minimal repetition, it is best to avoid long chains of if/else statements. One effective approach is to implement a scoring system where each item is assigned a unique score and the highest score indicates the desired item. There are numerous ways to achieve this, but one straightforward method involves assigning numerical values to 'felony' and 'misdemeanor' such that they are higher than any other categories. The 10s place represent felony/misdemeanors, while the 1s digit represents the ranking within those categories. By iterating through the array once using this scoring system, you can easily identify the item with the highest score:

let scores = {
  FELONY: 20,
  MISDEMEANOR: 10,
  '1st': 3,
  '2nd': 2,
  '3rd': 1
}

let arr = [["2nd", "FELONY"],["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"],["1st", "FELONY"]]

let highest = 0, result
for (item of arr) {
  let score = item.reduce((a, c) => a + scores[c], 0)
  if (score > highest) {
    highest = score
    result = item
  }
}
console.log(result)

This method also facilitates easy modifications to preferences or the addition of new categories without relying on alphabetical order for sorting.

Answer 3

Answer №2

If you're looking for a straightforward solution, you can consider the following:

function sortArray(a) {
  return [...a].sort(([aa, ab], [ba, bb]) => (ab + aa).localeCompare(bb + ba))
}

To implement this method, simply do the following:

const [selected] = sortArray(arr)

Key points to remember:

Copying the array using [...a] is necessary because the sort function modifies the original array
This specific sorting logic assumes that in your case, FELONY should come before MISDEMEANOR, and numbers like 1st, 2nd, etc., are involved
Although not the most efficient approach, it should suffice for your current requirements

If you need to sort other strings differently, you can utilize a lookup table as shown below:

const lookup = {
  FELONY: 1,
  MISDEMEANOR: 2,
  ...
}

sort(... => (lookup[ab] + lookup[aa]).localeCompare(...))

Answer 4

If you're looking for a straightforward solution, you can consider the following:

function sortArray(a) {
  return [...a].sort(([aa, ab], [ba, bb]) => (ab + aa).localeCompare(bb + ba))
}

To implement this method, simply do the following:

const [selected] = sortArray(arr)

Key points to remember:

Copying the array using [...a] is necessary because the sort function modifies the original array
This specific sorting logic assumes that in your case, FELONY should come before MISDEMEANOR, and numbers like 1st, 2nd, etc., are involved
Although not the most efficient approach, it should suffice for your current requirements

If you need to sort other strings differently, you can utilize a lookup table as shown below:

const lookup = {
  FELONY: 1,
  MISDEMEANOR: 2,
  ...
}

sort(... => (lookup[ab] + lookup[aa]).localeCompare(...))

Answer 5

Answer №3

Unsure whether the solution presented here is more sophisticated or effective than what you already have - I'll defer to the expertise of JavaScript professionals to provide feedback. Nevertheless, this is my attempt:

It should be noted that the following rough assumptions were taken into consideration :-|

The initial element of the inner array (sub-array) always begins with ordinal numbers like 1st, 2nd, etc.

1.1 The subsequent characters after the number are single digits (not exceeding 9).

var sampleArray = [ ["1st", "FELONY"], ["2nd", "FELONY"],  ["3rd", "FELONY"], ["1st", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"]] 
// var sampleArray = [["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]]
// var sampleArray = [["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]]

var reducedArray = sampleArray.reduce((a,b) => a.concat(b))

// Step 1: Filter out any instances of FELONY.
let result = [];
if(reducedArray.includes("FELONY")) {
sampleArray.forEach(a => {if(a.includes("FELONY")) {
    result.push(a);
}})
}else{
result = sampleArray;
}

// Step 2: Sort and retrieve the first element.

result.sort((a,b) => {
if(a[0].substring(0) < b[0].substring(0)) {
    return -1;
} else if(a[0].substring(0) > b[0].substring(0)){
    return 1;
}
return 0;
})

console.log(result[0]);

Answer 6

Unsure whether the solution presented here is more sophisticated or effective than what you already have - I'll defer to the expertise of JavaScript professionals to provide feedback. Nevertheless, this is my attempt:

It should be noted that the following rough assumptions were taken into consideration :-|

The initial element of the inner array (sub-array) always begins with ordinal numbers like 1st, 2nd, etc.

1.1 The subsequent characters after the number are single digits (not exceeding 9).

var sampleArray = [ ["1st", "FELONY"], ["2nd", "FELONY"],  ["3rd", "FELONY"], ["1st", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"]] 
// var sampleArray = [["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]]
// var sampleArray = [["2nd", "FELONY"], ["2nd", "MISDEMEANOR"], ["1st", "MISDEMEANOR"]]

var reducedArray = sampleArray.reduce((a,b) => a.concat(b))

// Step 1: Filter out any instances of FELONY.
let result = [];
if(reducedArray.includes("FELONY")) {
sampleArray.forEach(a => {if(a.includes("FELONY")) {
    result.push(a);
}})
}else{
result = sampleArray;
}

// Step 2: Sort and retrieve the first element.

result.sort((a,b) => {
if(a[0].substring(0) < b[0].substring(0)) {
    return -1;
} else if(a[0].substring(0) > b[0].substring(0)){
    return 1;
}
return 0;
})

console.log(result[0]);

Answer 7

Answer №4

Transforming your structure into an object structure can easily accommodate any number of people or rankings in the future.

const list = [ ["1st", "FELONY"], ["2nd", "FELONY"],  ["3nd", "FELONY"], ["1st", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"]]  

let obj = {}
list.forEach((item, index) => {
  obj = {
    ...obj,
    [item[1]] : {
       ...obj[item[1]],
       [item[0]]: index,
    }
  }
})

console.log(obj)

You can observe that for the given list above, our object appears as follows:

{
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

From this object structure, we can now retrieve the required value with ease.

const obj = {
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

let nameToLookFor = 'FELONY';
if (!obj[nameToLookFor]) {
  nameToLookFor = 'MISDEMEANOR'
}

const found = 
  obj[nameToLookFor]['1st'] || obj[nameToLookFor]['2nd'] || obj[nameToLookFor]['3rd']);

console.log(found)

const obj = {
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

let nameToLookFor = 'FELONY';
if (!obj[nameToLookFor]) {
  nameToLookFor = 'MISDEMEANOR'
}


const found = 
  obj[nameToLookFor]['1st'] || obj[nameToLookFor]['2nd'] || obj[nameToLookFor]['3rd'];

console.log(found)

Answer 8

Transforming your structure into an object structure can easily accommodate any number of people or rankings in the future.

const list = [ ["1st", "FELONY"], ["2nd", "FELONY"],  ["3nd", "FELONY"], ["1st", "MISDEMEANOR"], ["3rd", "MISDEMEANOR"]]  

let obj = {}
list.forEach((item, index) => {
  obj = {
    ...obj,
    [item[1]] : {
       ...obj[item[1]],
       [item[0]]: index,
    }
  }
})

console.log(obj)

You can observe that for the given list above, our object appears as follows:

{
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

From this object structure, we can now retrieve the required value with ease.

const obj = {
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

let nameToLookFor = 'FELONY';
if (!obj[nameToLookFor]) {
  nameToLookFor = 'MISDEMEANOR'
}

const found = 
  obj[nameToLookFor]['1st'] || obj[nameToLookFor]['2nd'] || obj[nameToLookFor]['3rd']);

console.log(found)

const obj = {
  "FELONY": {
    "1st": 0,
    "2nd": 1,
    "3nd": 2
  },
  "MISDEMEANOR": {
    "1st": 3,
    "3rd": 4
  }
}

let nameToLookFor = 'FELONY';
if (!obj[nameToLookFor]) {
  nameToLookFor = 'MISDEMEANOR'
}


const found = 
  obj[nameToLookFor]['1st'] || obj[nameToLookFor]['2nd'] || obj[nameToLookFor]['3rd'];

console.log(found)

Answer 9

Answer №5

function organizePenalties(data){
    const   felonies = data.filter(subArr => subArr[1] == "FELONY"),
            misdemeanors = data.filter(subArr => subArr[1] == "MISDEMEANOR");

    function sortData(arr){
      const sortedArray = [];

      for(let i = 0; i < arr.length; i++){
        sortedArray[arr[i][0][0] - 1] = arr[i];
      }

      return sortedArray[0] || sortedArray[1] || sortedArray[2];
    }

    return felonies.length > 0 ? sortData(felonies) : sortData(misdemeanors);
}

To begin with, I suggest using the ES6 filter array method to categorize felonies and misdemeanors. This method creates an array with elements that match a specified condition, in this case either "FELONY" or "MISDEMEANOR"
I then implemented a custom sorting function that takes in an array, iterates through it, and assigns each element to a new array based on a specified position. By extracting and adjusting the numerical value, we accurately place each item in its corresponding index in the newarr.
The final step of our custom sorting function is to return the first item encountered, depending on the input data. For example, if the input data is [["3rd", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"]], there would be no item at index 0, but one would exist at index 1, making the use of the || operator perfect for this scenario.
Lastly, a ternary operation checks whether there are any felonies by examining their length. If felony records are present, the function returns the sorted result for felonies; otherwise, it returns the sorted result for misdemeanors.

Answer 10

function organizePenalties(data){
    const   felonies = data.filter(subArr => subArr[1] == "FELONY"),
            misdemeanors = data.filter(subArr => subArr[1] == "MISDEMEANOR");

    function sortData(arr){
      const sortedArray = [];

      for(let i = 0; i < arr.length; i++){
        sortedArray[arr[i][0][0] - 1] = arr[i];
      }

      return sortedArray[0] || sortedArray[1] || sortedArray[2];
    }

    return felonies.length > 0 ? sortData(felonies) : sortData(misdemeanors);
}

To begin with, I suggest using the ES6 filter array method to categorize felonies and misdemeanors. This method creates an array with elements that match a specified condition, in this case either "FELONY" or "MISDEMEANOR"
I then implemented a custom sorting function that takes in an array, iterates through it, and assigns each element to a new array based on a specified position. By extracting and adjusting the numerical value, we accurately place each item in its corresponding index in the newarr.
The final step of our custom sorting function is to return the first item encountered, depending on the input data. For example, if the input data is [["3rd", "MISDEMEANOR"], ["2nd", "MISDEMEANOR"]], there would be no item at index 0, but one would exist at index 1, making the use of the || operator perfect for this scenario.
Lastly, a ternary operation checks whether there are any felonies by examining their length. If felony records are present, the function returns the sorted result for felonies; otherwise, it returns the sorted result for misdemeanors.

Retrieve specific elements from an array based on the other elements present in the array

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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