I'm writing a function to find the 10 most common words in a string. However, when I go to sort my arr it repeats some of the words for their values of count.

paragraph = `I love teaching. If you do not love teaching what else can you love. I love Python if you do not love something which can give you all the capabilities to develop an application what else can you love.`;
const tenMostFrequentWords = (str) => {
    const regex = /\b[a-z] \b/gi;
    const arr = str.match(regex);
    const set = new Set();
    for (word of arr) {
        const filteredArr = arr.filter(item => item == word);
        set.add({word: word, count: filteredArr.length});
    }
    const newArr = Array.from(set);
    newArr.sort((a,b) => b.count - a.count);
    return newArr;
}
console.log(tenMostFrequentWords(paragraph));

Why is this happening?

CodePudding user response：

You're adding new objects to the set in every iteration of your loop. A Set will compare them by reference (object identity), not by structural equality, so you're adding each word multiple times. Instead, use a Map for the counts by word (and don't use filter for counting, that amounts to quadratic complexity):

const tenMostFrequentWords = (str) => {
    const regex = /\b[a-z] \b/gi;
    const words = str.match(regex);
    const counts = new Map();
    for (word of words) {
        counts.set(word, (counts.get(word) ?? 0)   1);
    }
    const newArr = Array.from(counts, ([word, count]) => ({word, count}));
    newArr.sort((a,b) => b.count - a.count);
    return newArr.slice(0, 10);
}
const paragraph = `I love teaching. If you do not love teaching what else can you love. I love Python if you do not love something which can give you all the capabilities to develop an application what else can you love.`;
console.log(tenMostFrequentWords(paragraph));

CodePudding user response：

You iterate through arr and word "love" is in arr 6 times, so it will add it to set 6 times. Create another "arr" and every time you iterate check if the word has already been iterated over.