spam_011.swift

func idf(word:String) -> Double {
    if let pos = self.vocabulary[word] {
        return self.idf[pos]
    } else {
        return Double(0.0)
    }
}


func tfidf(sentence:String) -> [Int:Double] {
    let cv = countVector(sentence: sentence)
    var vec = [Int:Double]()

    cv?.forEach({ (key, value) in
        let i = self.idf[key]
        print(i)
        let t = Double(value) / Double(cv!.count)
        print(t)
        vec[key] = t * i
    })
    //vec now is TFIDF, but is not normalized
    if self.norm { //L2 Norm
        var sum = vec.flatMap{ $1 }.reduce(0) { $0 + $1*$1 }
        sum = sqrt(sum)

        var n = [Int:Double]()

        vec.forEach({ (key, value) in
            n[key] = value / sum
        })

        return n
    }
    return vec
}