Alphabet Frequency Chart: Counting the occurrences of each letter in a given string (even if it is 0)

Question

Alphabet Frequency Chart: Counting the occurrences of each letter in a given string (even if it is 0)

I have developed a function that generates an array showing the frequency of each letter in the alphabet (a-z) within a given string, including 0 occurrences. The array consists of 26 numbers representing each letter of the alphabet. Here is the function I have created so far. While it functions correctly, I believe there may be a more streamlined approach to improve this solution.

export function generateMap(text){

 const text_arr = text.toLowerCase().split('');
 const valid_char = 'abcdefghijklmnopqrstuvwxyz'.split('')

 const map = {'a': 0, 'b': 0, 'c': 0, 'd': 0, 'e': 0, 'f': 0, 'g': 0, 'h': 0, 'i': 0, 'j': 0, 'k': 0, 'l': 0, 'm': 0, 'n': 0, 'o': 0, 'p': 0, 'q': 0, 'r': 0, 's': 0, 't': 0, 'u': 0, 'v': 0, 'w': 0, 'x': 0, 'y': 0, 'z': 0}


 text_arr.forEach(char => {
   if(valid_char.indexOf(char) > -1) map[char]++
 })

 return Object.values(map)

}

javascript arrays hashtable

Answer 1

Answer №1

When it comes to utilizing ES6, one innovative approach is extending the Map object with additional features for a more seamless process. This involves implementing an update() function for semantic incrementation and a get() function that provides a default value (such as 0) if a key does not currently exist in the map:

class DefaultMap extends Map {
  constructor (defaultValue, iterable = []) {
    super(iterable)
    this.default = defaultValue
  }

  get (key) {
    if (this.has(key)) {
      return super.get(key)
    }

    return this.default
  }

  update (key, fn) {
    this.set(key, fn(this.get(key)))
  }
}

const initialCharCode = 'a'.charCodeAt(0)

// create valid characters based on the ASCII table for characters a-z
const validChars = Array.from(
  {length: 26},
  (value, index) => String.fromCharCode(index + initialCharCode)
)

function generateMap (text) {
  const chars = text.replace(/[^a-z]/gi, '').toLowerCase().split('')
  const map = new DefaultMap(0)

  chars.forEach(char => map.update(char, count => count + 1))

  return validChars.map(validChar => map.get(validChar))
}

console.log(generateMap('Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.'))

In addition, the validChars are defined only once outside the generateMap() function to avoid redundant declarations. It is also beneficial to retrieve our array by mapping validChars rather than using Object.values() on the map, ensuring that the iteration order adheres to specifications rather than implementation-specific behavior.

Answer 2

When it comes to utilizing ES6, one innovative approach is extending the Map object with additional features for a more seamless process. This involves implementing an update() function for semantic incrementation and a get() function that provides a default value (such as 0) if a key does not currently exist in the map:

class DefaultMap extends Map {
  constructor (defaultValue, iterable = []) {
    super(iterable)
    this.default = defaultValue
  }

  get (key) {
    if (this.has(key)) {
      return super.get(key)
    }

    return this.default
  }

  update (key, fn) {
    this.set(key, fn(this.get(key)))
  }
}

const initialCharCode = 'a'.charCodeAt(0)

// create valid characters based on the ASCII table for characters a-z
const validChars = Array.from(
  {length: 26},
  (value, index) => String.fromCharCode(index + initialCharCode)
)

function generateMap (text) {
  const chars = text.replace(/[^a-z]/gi, '').toLowerCase().split('')
  const map = new DefaultMap(0)

  chars.forEach(char => map.update(char, count => count + 1))

  return validChars.map(validChar => map.get(validChar))
}

console.log(generateMap('Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.'))

In addition, the validChars are defined only once outside the generateMap() function to avoid redundant declarations. It is also beneficial to retrieve our array by mapping validChars rather than using Object.values() on the map, ensuring that the iteration order adheres to specifications rather than implementation-specific behavior.

Answer 3

Answer №2

Update:

function createCharacterMap(input){

    let inputArray = input.toLowerCase().split('').sort();

    const validCharacters = 'abcdefghijklmnopqrstuvwxyz'.split('').sort();
    const charMap = {};

    validCharacters.forEach(character => {
        let count = inputArray.lastIndexOf(character) + 1;
        inputArray = inputArray.slice(count);
        charMap[character] = count;
    });

    return Object.values(charMap)
}

The sort() function on validCharacters is crucial for proper execution.

Answer 4

Update:

function createCharacterMap(input){

    let inputArray = input.toLowerCase().split('').sort();

    const validCharacters = 'abcdefghijklmnopqrstuvwxyz'.split('').sort();
    const charMap = {};

    validCharacters.forEach(character => {
        let count = inputArray.lastIndexOf(character) + 1;
        inputArray = inputArray.slice(count);
        charMap[character] = count;
    });

    return Object.values(charMap)
}

The sort() function on validCharacters is crucial for proper execution.

Alphabet Frequency Chart: Counting the occurrences of each letter in a given string (even if it is 0)

Answer №1

Answer №2

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