Consider pushing items onto an array only once when the condition is met, instead of adding to the array every

Question

Consider pushing items onto an array only once when the condition is met, instead of adding to the array every

I have been tasked with importing Excel files containing customer orders into my web application. The process involves converting the data in the file into an object of arrays, where each array represents a row from the Excel sheet.

Once the data is imported, I need to search for specific items within a column to identify the shoe brands requested by customers. However, I encountered an issue where the same column data was being pushed into the array multiple times instead of just once.

In the code snippet below, you can see how I attempted to address this problem using conditional statements:


for (let i = 0; i < this.data.length; i++) {
    if (this.data[i].indexOf('Adidas') !== -1) {
        let brandIndex = this.data[i].indexOf('Adidas');
        for (let j = 0; j < this.data.length; j++) {
            this.brandArray.push(this.data[j][brandIndex]);
        }
    } else if (this.data[i].indexOf('Puma') !== -1) {
        let brandIndex = this.data[i].indexOf('Puma');
        for (let j = 0; j < this.data.length; j++) {
            this.brandArray.push(this.data[j][brandIndex]);
        }
    } else if (this.data[i].indexOf('Nike') !== -1) {
        let brandIndex = this.data[i].indexOf('Nike');
        for (let j = 0; j < this.data.length; j++) {
            this.brandArray.push(this.data[j][brandIndex]);
        }
    }
}

The current implementation pushes the column data into the array every time a condition is met. Is there a more efficient way, possibly utilizing the '%' operator or another function, to ensure that each column is only added to the array once?

If, for example, I had a customer sheet with the following entries:

https://i.stack.imgur.com/G62py.png

I would like the resulting array to be

[Nike, Adidas, Puma, Puma, Asics, Nike]

javascript arrays typescript algorithm

Answer 1

Answer №1

If you want to efficiently add unique elements without checking if they already exist in an array, consider using a Set data structure. By adding elements to a Set and then converting it back to an array, you can avoid the potential O(n²) time complexity that may arise from repeatedly checking for duplicates in an array.

Here is an example of how you can use a Set:

const mySet = new Set();

mySet.add(123);
console.log([...mySet]);

mySet.add("hello world");
console.log([...mySet]);

mySet.add(123);
console.log([...mySet]);

To convert a Set back to an array, you can use either [...mySet] or Array.from(mySet).

In your code snippet, you are initializing a Set called manufactSet and populating it with unique values. After processing the data, you convert the Set back to an array named manufactArray.

However, there seems to be confusion in the loop logic where you push all elements when encountering a specific value ('Adidas'). It might be more appropriate to push only that specific element rather than the entire row. Consider revising this section of your code accordingly.

Based on your requirements, it appears that you want to extract specific manufacturers multiple times from different rows. In this case, utilizing a Set may not be suitable. Here's an optimized version of your code in ES6:

const someManufacturers = new Set(['Adidas', 'Puma', 'Nike']);

function getColumnNumber() {
  for (const row of this.data) {
    for (let i = 0; i < row.length; i++) {
      if (someManufacturers.has(row[i])) return i;
    }
  }
}
var manufacturerColumnNumber = getColumnNumber();

for (const row of this.data) {
  this.manufactArray.push(row[manufacturerColumnNumber]);
}

By adjusting your implementation as suggested above, you can achieve the desired functionality more efficiently while avoiding unnecessary iterations through the data.

Answer 2

If you want to efficiently add unique elements without checking if they already exist in an array, consider using a Set data structure. By adding elements to a Set and then converting it back to an array, you can avoid the potential O(n²) time complexity that may arise from repeatedly checking for duplicates in an array.

Here is an example of how you can use a Set:

const mySet = new Set();

mySet.add(123);
console.log([...mySet]);

mySet.add("hello world");
console.log([...mySet]);

mySet.add(123);
console.log([...mySet]);

To convert a Set back to an array, you can use either [...mySet] or Array.from(mySet).

In your code snippet, you are initializing a Set called manufactSet and populating it with unique values. After processing the data, you convert the Set back to an array named manufactArray.

However, there seems to be confusion in the loop logic where you push all elements when encountering a specific value ('Adidas'). It might be more appropriate to push only that specific element rather than the entire row. Consider revising this section of your code accordingly.

Based on your requirements, it appears that you want to extract specific manufacturers multiple times from different rows. In this case, utilizing a Set may not be suitable. Here's an optimized version of your code in ES6:

const someManufacturers = new Set(['Adidas', 'Puma', 'Nike']);

function getColumnNumber() {
  for (const row of this.data) {
    for (let i = 0; i < row.length; i++) {
      if (someManufacturers.has(row[i])) return i;
    }
  }
}
var manufacturerColumnNumber = getColumnNumber();

for (const row of this.data) {
  this.manufactArray.push(row[manufacturerColumnNumber]);
}

By adjusting your implementation as suggested above, you can achieve the desired functionality more efficiently while avoiding unnecessary iterations through the data.

Consider pushing items onto an array only once when the condition is met, instead of adding to the array every

Answer №1

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