Top method for combining an array prefix with a reversed array prefix

Question

Top method for combining an array prefix with a reversed array prefix

When given two arrays and indices, the task is to combine a portion of the first array with a reversed portion of the second array.

For instance:

// Provided Input
arr1 = [1,2,3,4,5,6,7,8,9];
arr2 = [10,11,12,13,14,15];
ind1 = 6;
ind2 = 3;

// Expected Output
arr = [1,2,3,4,5,6,12,11,10];

This is my current implementation:

function Concat(arr1,arr2,ind1,ind2) {
    let arr = [];
    for (let n = 0; n < ind1; n++)
        arr.push(arr1[n]);
    for (let n = ind2; n > 0; n--)
        arr.push(arr2[n-1]);
    return arr;
}

I am open to suggestions on how this can be improved in terms of efficiency or simplicity. Any ideas?

javascript arrays

Answer 1

Answer №1

Consider trying out the following approach:

Note: While this may not offer a significant speed improvement over your current method, it does provide a cleaner solution.

function CombineArrays(arr1,arr2,index1,index2) {
  return [].concat(arr1.slice(0, index1), arr2.slice(0, index2).reverse());
}

arr1 = [1,2,3,4,5,6,7,8,9];
arr2 = [10,11,12,13,14,15];
index1 = 6;
index2 = 3;

console.log(CombineArrays(arr1, arr2, index1, index2))

As mentioned earlier, the performance impact of this method is not substantial. You can compare the results here on js-perf.

An alternative approach is available if you have the flexibility to modify the input structure.

By expecting an array of objects in a specific order, we can simplify the code and make it more generic. Assuming the structure as follows:

_{Kindly consider the syntax, as my primary language is TypeScript which influences my writing style.}

interface CombinedStructure {
  values: Array<any>;
  endIndex: number;
  shouldReverse: boolean
}

This structural change enhances readability and makes the code easier to customize.

function CombineCustomData(arr) {
  return arr.reduce(function(acc, cur) {
    var tempArray = cur.values.slice(0, cur.endIndex);
    if (cur.shouldReverse) {
      tempArray = tempArray.reverse();
    }
    return acc.concat(tempArray);
  }, []);
}

var inputData = [{
    values: [1, 2, 3, 4, 5, 6, 7, 8, 9],
    endIndex: 6
  },
  {
    values: [10, 11, 12, 13, 14, 15],
    endIndex: 3,
    shouldReverse: true
  }
]

console.log(CombineCustomData(inputData))

Answer 2

Consider trying out the following approach:

Note: While this may not offer a significant speed improvement over your current method, it does provide a cleaner solution.

function CombineArrays(arr1,arr2,index1,index2) {
  return [].concat(arr1.slice(0, index1), arr2.slice(0, index2).reverse());
}

arr1 = [1,2,3,4,5,6,7,8,9];
arr2 = [10,11,12,13,14,15];
index1 = 6;
index2 = 3;

console.log(CombineArrays(arr1, arr2, index1, index2))

As mentioned earlier, the performance impact of this method is not substantial. You can compare the results here on js-perf.

An alternative approach is available if you have the flexibility to modify the input structure.

By expecting an array of objects in a specific order, we can simplify the code and make it more generic. Assuming the structure as follows:

_{Kindly consider the syntax, as my primary language is TypeScript which influences my writing style.}

interface CombinedStructure {
  values: Array<any>;
  endIndex: number;
  shouldReverse: boolean
}

This structural change enhances readability and makes the code easier to customize.

function CombineCustomData(arr) {
  return arr.reduce(function(acc, cur) {
    var tempArray = cur.values.slice(0, cur.endIndex);
    if (cur.shouldReverse) {
      tempArray = tempArray.reverse();
    }
    return acc.concat(tempArray);
  }, []);
}

var inputData = [{
    values: [1, 2, 3, 4, 5, 6, 7, 8, 9],
    endIndex: 6
  },
  {
    values: [10, 11, 12, 13, 14, 15],
    endIndex: 3,
    shouldReverse: true
  }
]

console.log(CombineCustomData(inputData))

Answer 3

Answer №2

To solve this without any issues, you can utilize the following code:

var arr1 = [1,2,3,4,5,6,7,8,9];
var arr2 = [10,11,12,13,14,15];
var ind1 = 6;
var ind2 = 3;
var output = [...arr1.slice(0, ind1), ...arr2.slice(0, ind2).reverse()];
console.log(output);

If you prefer not to employ ES6 spread syntax, you can opt for array.prototype.concat:

var arr1 = [1,2,3,4,5,6,7,8,9];
var arr2 = [10,11,12,13,14,15];
var ind1 = 6;
var ind2 = 3;
var output = arr1.slice(0, ind1).concat(arr2.slice(0, ind2).reverse());
console.log(output);

Answer 4

To solve this without any issues, you can utilize the following code:

var arr1 = [1,2,3,4,5,6,7,8,9];
var arr2 = [10,11,12,13,14,15];
var ind1 = 6;
var ind2 = 3;
var output = [...arr1.slice(0, ind1), ...arr2.slice(0, ind2).reverse()];
console.log(output);

If you prefer not to employ ES6 spread syntax, you can opt for array.prototype.concat:

var arr1 = [1,2,3,4,5,6,7,8,9];
var arr2 = [10,11,12,13,14,15];
var ind1 = 6;
var ind2 = 3;
var output = arr1.slice(0, ind1).concat(arr2.slice(0, ind2).reverse());
console.log(output);

Answer 5

Answer №3

Easiest way to merge two arrays

Example:

// array declaration
let firstArray = [1,2,3,4,5,6,7,8,9];
let secondArray = [10,11,12,13,14,15];
let indexOne = 6;
let indexTwo = 3;
var mergedArray = [];

// adjust length based on indexes
firstArray.length = indexOne;
secondArray.length = indexTwo;

// reverse and concatenate the arrays
mergedArray = firstArray.concat(secondArray.reverse());
console.log(mergedArray);

Efficient and clear approach.

Answer 6

Easiest way to merge two arrays

Example:

// array declaration
let firstArray = [1,2,3,4,5,6,7,8,9];
let secondArray = [10,11,12,13,14,15];
let indexOne = 6;
let indexTwo = 3;
var mergedArray = [];

// adjust length based on indexes
firstArray.length = indexOne;
secondArray.length = indexTwo;

// reverse and concatenate the arrays
mergedArray = firstArray.concat(secondArray.reverse());
console.log(mergedArray);

Efficient and clear approach.

Answer 7

Answer №4

Utilizing ES6 features

let arrayOne = [1,2,3,4,5,6,7,8,9],
    arrayTwo = [10,11,12,13,14,15];
let indexOne = 6,
    indexTwo = 3;

let newArray = [...arrayOne.slice(0, indexOne), ...arrayTwo.slice(0, indexTwo).reverse()];

console.log(newArray)

Answer 8

Utilizing ES6 features

let arrayOne = [1,2,3,4,5,6,7,8,9],
    arrayTwo = [10,11,12,13,14,15];
let indexOne = 6,
    indexTwo = 3;

let newArray = [...arrayOne.slice(0, indexOne), ...arrayTwo.slice(0, indexTwo).reverse()];

console.log(newArray)

Answer 9

Answer №5

If you need to combine multiple arrays, consider utilizing this technique. It enables you to merge any number of arrays in a specific order using the function cascading concept. You can chain together this cascading approach and take advantage of optional parameters for reversing the order if needed.

const arr1 = [1,2,3,4,5,6,7,8,9];
const arr2 = [10,11,12,13,14,15];

const obj = {
  items: [],
  concat(arr, index, isReverse = false) {
     let temp = arr.slice(0, index);
     this.items = this.items.concat(isReverse ? temp.reverse() : temp);
     return this;
  }
};

obj.concat(arr1, 6).concat(arr2, 3, true);
console.log(obj.items);

Answer 10

If you need to combine multiple arrays, consider utilizing this technique. It enables you to merge any number of arrays in a specific order using the function cascading concept. You can chain together this cascading approach and take advantage of optional parameters for reversing the order if needed.

const arr1 = [1,2,3,4,5,6,7,8,9];
const arr2 = [10,11,12,13,14,15];

const obj = {
  items: [],
  concat(arr, index, isReverse = false) {
     let temp = arr.slice(0, index);
     this.items = this.items.concat(isReverse ? temp.reverse() : temp);
     return this;
  }
};

obj.concat(arr1, 6).concat(arr2, 3, true);
console.log(obj.items);

Top method for combining an array prefix with a reversed array prefix

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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