/*
This program finds the N most frequently appearing words in a text
after removing stopwords. It demonstrates clean structure, clear
comments, and efficient use of Scala collections and sorting.
*/
object TopWordsScala {
// ---------------------------------------------------------------
// Tokenize text into words (simple whitespace split)
// ---------------------------------------------------------------
def tokenize(text: String): List[String] = {
text
.split("\\s+")
.toList
.map { w =>
// Remove punctuation at the edges using regex
val trimmed = w.replaceAll("^\\p{Punct}+|\\p{Punct}+$", "")
trimmed.toLowerCase
}
.filter(_.nonEmpty)
}
// ---------------------------------------------------------------
// Count word frequencies, skipping stopwords
// ---------------------------------------------------------------
def countWordsFrequencies(
words: List[String],
stopwords: Set[String]
): Map[String, Int] = {
words
.filterNot(stopwords.contains)
.groupBy(identity)
.view
.mapValues(_.size)
.toMap
}
// ---------------------------------------------------------------
// Extract the top N most frequent words
// ---------------------------------------------------------------
def topN(freq: Map[String, Int], n: Int): List[(String, Int)] = {
freq.toList
.sortBy { case (word, count) => (-count, word) }
.take(n)
}
// ---------------------------------------------------------------
// Main
// ---------------------------------------------------------------
def main(args: Array[String]): Unit = {
val text =
"C is a general-purpose programming language created in 1972 by " +
"Dennis Ritchie. C gives programmers direct access to the features " +
"of CPU. It has been and continues to be used to implement " +
"operating systems (especially kernels) and device " +
"drivers. C programming language used on computers ranging from " +
"supercomputers to microcontrollers and embedded systems."
val stopwords: Set[String] = Set(
"the","is","a","to","how","after","but","this","for","by","in",
"and","can","content","be","you","yes","no","next","about","used",
"access","been","continues"
)
// Tokenize
val words = tokenize(text)
// Count frequencies
val freq = countWordsFrequencies(words, stopwords)
// Get top n
val n = 7
val topn = topN(freq, n)
// Print results
println(s"Top $n most frequent non-stopwords:")
topn.foreach { case (word, count) =>
println(s"$word : $count")
}
}
}
/*
run:
Top 7 most frequent non-stopwords:
c : 3
language : 2
programming : 2
systems : 2
1972 : 1
computers : 1
cpu : 1
*/
