What is the best way to utilize the _.uniq function in underscore to efficiently track and distinguish between even and odd numbers?

Question

What is the best way to utilize the _.uniq function in underscore to efficiently track and distinguish between even and odd numbers?

Just getting started with JavaScript and I've made some progress. My goal is to use underscore to display two sets of unique even and odd numbers on the console, but I seem to have hit a roadblock at about 90% completion.

var arr = ([1,3,5,2,0,4,5,2,9,9,8,2]);            
sort(arr);

function sort(arr) {

var evens = [];
var odds = [];                        
for(var i = 0; i < arr.length; i++) {            
    if(arr[i] % 2 ){            
        odds.push(arr[i]);            
    } else if(!(arr[i] % 2)) {            
        evens.push(arr[i]);            
}            
}            

console.log("ODD NUMBERS:" + " " + odds);            
console.log("EVEN NUMBERS:" + " " + evens);            
if(_.uniq(evens).length != evens.length || _.uniq(odds).length != odds.length){            
console.log("FAIL!");            
}             
}

javascript arrays sorting underscore.js unique

Answer 1

Answer №1

To start, sort your array by separating the even and odd numbers, then utilize _.uniq

var arr = [1,3,5,2,0,4,5,2,9,9,8,2];

var evens = _.filter(arr, function(num){ return num % 2 == 0; });
var odds = _.filter(arr, function(num){ return num % 2 != 0; });

console.log("EVEN NUMBERS: "+_.uniq(evens));
console.log("ODD NUMBERS: "+_.uniq(odds));

<script src="http://underscorejs.org/underscore-min.js"></script>

Answer 2

To start, sort your array by separating the even and odd numbers, then utilize _.uniq

var arr = [1,3,5,2,0,4,5,2,9,9,8,2];

var evens = _.filter(arr, function(num){ return num % 2 == 0; });
var odds = _.filter(arr, function(num){ return num % 2 != 0; });

console.log("EVEN NUMBERS: "+_.uniq(evens));
console.log("ODD NUMBERS: "+_.uniq(odds));

<script src="http://underscorejs.org/underscore-min.js"></script>

Answer 3

Answer №2

arr[i] % 2 results in 0, which is equivalent to false in the condition of an if statement.

if (arr[i] % 2 === 0) { 
  // this code block executes when the number is even
} else {
  // this code block executes when the number is not even
}

Answer 4

arr[i] % 2 results in 0, which is equivalent to false in the condition of an if statement.

if (arr[i] % 2 === 0) { 
  // this code block executes when the number is even
} else {
  // this code block executes when the number is not even
}

Answer 5

Answer №3

Uncertain if I have correctly understood your needs, however, below is a solution using ES6.

filter method is well-supported across most browsers and allows for better array manipulation in a declarative manner.

const arr = [1,3,5,2,0,4,5,2,9,9,8,2]; 
const isEven = el => el % 2 === 0;
const isOdd = el => el % 2 !== 0;
const evens = arr.filter(isEven);
const odds = arr.filter(isOdd);
console.log(`Unique evens: ${_.uniq(evens)}`); // => "Unique evens: 2,0,4,8"
console.log(`Unique odds: ${_.uniq(odds)}`); // "Unique odds: 1,3,5,9"

Answer 6

Uncertain if I have correctly understood your needs, however, below is a solution using ES6.

filter method is well-supported across most browsers and allows for better array manipulation in a declarative manner.

const arr = [1,3,5,2,0,4,5,2,9,9,8,2]; 
const isEven = el => el % 2 === 0;
const isOdd = el => el % 2 !== 0;
const evens = arr.filter(isEven);
const odds = arr.filter(isOdd);
console.log(`Unique evens: ${_.uniq(evens)}`); // => "Unique evens: 2,0,4,8"
console.log(`Unique odds: ${_.uniq(odds)}`); // "Unique odds: 1,3,5,9"

Answer 7

Answer №4

Primary issue:

ReferenceError: _ is not defined.

Make sure that you have included the Underscore library in your HTML file using

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>

, or that Underscore has been properly required in your JavaScript file.

Secondary problem: "I expect no errors and both lists to be displayed in the console with distinct values."
This expected outcome isn't occurring because you need to execute the uniq function on the arrays. Simply wrap the two arrays with _.uniq() as shown below:

console.log("ODD NUMBERS:", _.uniq(odds));
console.log("EVEN NUMBERS:", _.uniq(evens));

Alternatively, you can apply _.uniq to the input array before sorting it, which will optimize processing time during sorting.

Regardless of the approach taken, assuming that Underscore is correctly implemented, the desired results should be achieved.

Answer 8

Primary issue:

ReferenceError: _ is not defined.

Make sure that you have included the Underscore library in your HTML file using

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>

, or that Underscore has been properly required in your JavaScript file.

Secondary problem: "I expect no errors and both lists to be displayed in the console with distinct values."
This expected outcome isn't occurring because you need to execute the uniq function on the arrays. Simply wrap the two arrays with _.uniq() as shown below:

console.log("ODD NUMBERS:", _.uniq(odds));
console.log("EVEN NUMBERS:", _.uniq(evens));

Alternatively, you can apply _.uniq to the input array before sorting it, which will optimize processing time during sorting.

Regardless of the approach taken, assuming that Underscore is correctly implemented, the desired results should be achieved.

What is the best way to utilize the _.uniq function in underscore to efficiently track and distinguish between even and odd numbers?

Answer №1

Answer №2

Answer №3

Answer №4

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