What is the best way to calculate the frequency of a specific word in an array?

Question

What is the best way to calculate the frequency of a specific word in an array?

I have been attempting to eliminate duplicates from my array and determine the frequency of each word appearing in the array. While I have come across methods to address this issue, none of them seem to be working. For instance, when I input the text "this this is a test test," the final sorted list is:

1 - is

1 - a

2 - this

2 - test

Although I intend to eventually reverse the array so that the highest numbers appear first, this result is exactly what I am looking for! However, changing the text slightly to something like "this is a test test this" completely disrupts the order:

1 - this

1 - is

1 - a

1 - this

2 - test

Here, 'test' appears twice as expected, but 'this' shows up twice in the list with a count of '1' each time. This only occurs for consecutive duplicates. How can this be prevented?

Below is the code snippet I am currently using:

<!DOCTYPE html>
<html>
<body>

<p>Click the button to display the array values after splitting.</p>

<button onclick="analyze()">Analyze</button>

<p id="displayText"></p>

<script>
function compareWordCount(a,b) {
  if (parseInt(a) < parseInt(b))
    return -1;
  return 1;
}

function analyze() {
    var str = "this is a test test this";
    var res = str.split(" ");
    document.getElementById("displayText").innerHTML = res;
    document.getElementById("displayText").innerHTML += "<br/><br/>The number of words is: " + res.length + "<br/><br/><br/>";

    document.getElementById("displayText").innerHTML += "The list of words:<br/><br/>";

    var words = [];

    var wordsWithCount = [];

    for (i = 0; i < res.length; i++) {
        words.push(res[i]);
        document.getElementById("displayText").innerHTML += words[i] + "<br/><br/>";
    }

    var current = null;
    var cnt = 0;
    for (var i = 0; i < words.length; i++) {
        if (words[i] != current) {
            if (cnt > 0) {
                document.getElementById("displayText").innerHTML += "<br/><br/>" + cnt + " - " + current + "<br/>";
                wordsWithCount.push(cnt + " - " + current);
            }
            current = words[i];
            cnt = 1;
        } else {
            cnt++;
        }
    }

    if (cnt > 0) {
        document.getElementById("displayText").innerHTML += "<br/><br/>" + cnt + " - " + current + "<br/>";
        wordsWithCount.push(cnt + " - " + current);
    }

    wordsWithCount.sort(compareWordCount);

    document.getElementById("displayText").innerHTML += "<br/><br/><br/><br/><br/>The list of SORTED words:<br/><br/>";

    for (i = 0; i < wordsWithCount.length; i++) {
        document.getElementById("displayText").innerHTML += wordsWithCount[i] + "<br/><br/>";
    }
}
</script>

</body>
</html>

javascript arrays

Answer 1

Answer №1

Below is a potential resolution using a combination of the for loop and Array.prototype.forEach() method:

let sentence = "One Two Three One One Three Two One Two Three",
    words = sentence.split(' '),
    result = {},
    count = 0;
    
for (let i = 0; i < words.length; i++) {
  count = 0;
  words.forEach(function (word) {
    if (word === words[i]) {
      count++;
    }
  });
  if (!result[words[i]]) {
    result[words[i]] = count;
  }
}

console.log(result);

Answer 2

Below is a potential resolution using a combination of the for loop and Array.prototype.forEach() method:

let sentence = "One Two Three One One Three Two One Two Three",
    words = sentence.split(' '),
    result = {},
    count = 0;
    
for (let i = 0; i < words.length; i++) {
  count = 0;
  words.forEach(function (word) {
    if (word === words[i]) {
      count++;
    }
  });
  if (!result[words[i]]) {
    result[words[i]] = count;
  }
}

console.log(result);

Answer 3

Answer №2

GSerg's observation about this being a duplicate seems valid, but let's delve into the logic behind your code to clarify what's happening step by step:

Initially, you break down the string this is a test test this into an array:

words = [this, is, a, test, test, this]

As you loop through the array, you compare each word to the previous one. If they match, you increment a counter. If not, you add the previous word to the wordsWithCount array.

The issue arises when you encounter the second occurrence of this in the array. The problem stems from starting a new counter for the second instance instead of continuing with the existing one.

To address this, consider using a key-value structure like this:

for (var i = 0; i < words.length; i++) {
    if(wordsWithCount[words[i]] === undefined) {
        wordsWithCount[words[i]] = 1;
    } else {
        wordsWithCount[words[i]]++;
    }
}

This approach yields the desired structure:

wordsWithCount: {
    'this': 2,
    'is': 1,
    'a': 1,
    'test': 2
}

You can then iterate through this structure to generate the formatted list you mentioned:

var formattedWordsWithCount = [];
for (var word in wordsWithCount) {
    formattedWordsWithCount.push(wordsWithCount[word] + " - " + word);
}

Answer 4

GSerg's observation about this being a duplicate seems valid, but let's delve into the logic behind your code to clarify what's happening step by step:

Initially, you break down the string this is a test test this into an array:

words = [this, is, a, test, test, this]

As you loop through the array, you compare each word to the previous one. If they match, you increment a counter. If not, you add the previous word to the wordsWithCount array.

The issue arises when you encounter the second occurrence of this in the array. The problem stems from starting a new counter for the second instance instead of continuing with the existing one.

To address this, consider using a key-value structure like this:

for (var i = 0; i < words.length; i++) {
    if(wordsWithCount[words[i]] === undefined) {
        wordsWithCount[words[i]] = 1;
    } else {
        wordsWithCount[words[i]]++;
    }
}

This approach yields the desired structure:

wordsWithCount: {
    'this': 2,
    'is': 1,
    'a': 1,
    'test': 2
}

You can then iterate through this structure to generate the formatted list you mentioned:

var formattedWordsWithCount = [];
for (var word in wordsWithCount) {
    formattedWordsWithCount.push(wordsWithCount[word] + " - " + word);
}

Answer 5

Answer №3

Utilize an object to keep track of the frequency of each word:

    var sentence = "this is a test test this";
    var wordsArray = sentence.split(" ");
    var wordFrequency = {};

    for (var i = 0; i < wordsArray.length; i++) {
        var currentWord = wordsArray[i];
        if (currentWord in wordFrequency) {
            wordFrequency[currentWord]++;
        } else {
            wordFrequency[currentWord] = 1;
        }
    }

    console.log("WORD FREQUENCY");

    for (currentWord in wordFrequency) {
        console.log(currentWord + " - " + wordFrequency[currentWord]);
    }
    
    var sortedWords = [];
    for (var currentWord in wordFrequency) {
        sortedWords.push([currentWord, wordFrequency[currentWord]]);
    }
    
    sortedWords.sort(function(a, b) {
        return b[1] - a[1];
    });
    
    console.log("SORTED WORD FREQUENCY");
    
    for (var i = 0; i < sortedWords.length; i++) {
        var word = sortedWords[i][0];
        console.log(word + " - " + wordFrequency[word]);
    }

Answer 6

Utilize an object to keep track of the frequency of each word:

    var sentence = "this is a test test this";
    var wordsArray = sentence.split(" ");
    var wordFrequency = {};

    for (var i = 0; i < wordsArray.length; i++) {
        var currentWord = wordsArray[i];
        if (currentWord in wordFrequency) {
            wordFrequency[currentWord]++;
        } else {
            wordFrequency[currentWord] = 1;
        }
    }

    console.log("WORD FREQUENCY");

    for (currentWord in wordFrequency) {
        console.log(currentWord + " - " + wordFrequency[currentWord]);
    }
    
    var sortedWords = [];
    for (var currentWord in wordFrequency) {
        sortedWords.push([currentWord, wordFrequency[currentWord]]);
    }
    
    sortedWords.sort(function(a, b) {
        return b[1] - a[1];
    });
    
    console.log("SORTED WORD FREQUENCY");
    
    for (var i = 0; i < sortedWords.length; i++) {
        var word = sortedWords[i][0];
        console.log(word + " - " + wordFrequency[word]);
    }

Answer 7

Answer №4

Check out this clever solution that can handle case sensitivity and punctuation.

function cleanWord(word) {
  let cleaned;
  const regex = /(\w+)/g.exec(word.toLowerCase().trim());
  if(regex) {
    cleaned = regex[1];
  }
  return cleaned;
}

function countWords(str) {
  let wordCount = {};
  str.split(" ").forEach((word) => {
    word = cleanWord(word);
    if(word) {
      if (wordCount.hasOwnProperty(word)) {
        wordCount[word] = wordCount[word] + 1;
      } else {
        wordCount[word] = 1;
      }
    }
  });
  return wordCount;
}

console.log(countWords("This, . is a test! test this this"));

Answer 8

Check out this clever solution that can handle case sensitivity and punctuation.

function cleanWord(word) {
  let cleaned;
  const regex = /(\w+)/g.exec(word.toLowerCase().trim());
  if(regex) {
    cleaned = regex[1];
  }
  return cleaned;
}

function countWords(str) {
  let wordCount = {};
  str.split(" ").forEach((word) => {
    word = cleanWord(word);
    if(word) {
      if (wordCount.hasOwnProperty(word)) {
        wordCount[word] = wordCount[word] + 1;
      } else {
        wordCount[word] = 1;
      }
    }
  });
  return wordCount;
}

console.log(countWords("This, . is a test! test this this"));

What is the best way to calculate the frequency of a specific word in an array?

Answer №1

Answer №2

Answer №3

Answer №4

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