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Finding the most frequent word(s) in an array using JavaScript
Problem
We are required to write a JavaScript function that takes in an array, arr, of strings of English lowercase alphabets as the first argument. The second argument to our function is a number, num (num < length of arr).
Our function is supposed to return the num most frequent elements in the array arr.
The answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first.
For example, if the input to the function is
Input
const arr = ["the", "day", "is", "sunny", "the", "the", "the", "sunny", "is", "is"]; const num = 4;
Output
const output = ["the", "is", "sunny", "day"];
Output Explanation
"the", "is", "sunny" and "day" are the four most frequent words,
with the number of occurrences being 4, 3, 2 and 1 respectively.
Example
Following is the code −
const arr = ["the", "day", "is", "sunny", "the", "the", "the", "sunny", "is", "is"];
const num = 4;
const mostFrequent = (arr = [], num = 1) => {
const map = {};
let keys = [];
for (let i = 0; i < arr.length; i++) {
if (map[arr[i]]) {
map[arr[i]]++;
} else {
map[arr[i]] = 1;
}
}
for (let i in map) {
keys.push(i);
}
keys = keys.sort((a, b) => {
if (map[a] === map[b]) {
if (a > b) {
return 1;
} else {
return -1;
}
}
else {
return map[b] - map[a];
}
})
.slice(0, num);
return keys;
};
console.log(mostFrequent(arr, num));Output
[ 'the', 'is', 'sunny', 'day' ]
Updated on: 24-Apr-2021
687 Views
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