跟踪文本文件中字符的频率

Question

因此，对于我当前的数据结构项目，我必须读取一个文本文件并最终对字符进行 Huffman 编码，然后返回新编码的文件（我还没有接近这些文件）。

我要做的第一件事是扫描文件并确定每个字符的频率，然后创建所有字符及其频率的有序列表。但是，我很难想出一个很好的方法来保持频率和现有字符的运行总数。我认为 Hashtable 可能是一个好主意，其中每个键都是一个字符，它映射到的值是它的频率。

有没有更有效的方法来做到这一点？

提前致谢！

Answer 1

这是我使用文本文件查找字符频率的代码。

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Locale;


public class Frequency2 {

    private static char[] myarry;
    private static int[] count = new int[26];
    private static double[] precntage=new double[26];
    private static double totCount=0;


    public static void main(String[] args) throws FileNotFoundException, IOException {

        String ss = new Frequency().readFile("E:/look.txt");//path of the text file
        //System.out.println(ss);
        ss = ss.toLowerCase(Locale.ENGLISH); // put all text to lowercase

        myarry = ss.toCharArray();  // text put a char array
        //count the characters
        for (int i = 0; i < myarry.length; i++) {
            if (myarry[i] == 'a') {
                count[0] = count[0] + 1;
            } else if (myarry[i] == 'b') {
                count[1] = count[1] + 1;
            } else if (myarry[i] == 'c') {
                count[2] = count[2] + 1;
            } else if (myarry[i] == 'd') {
                count[3] = count[3] + 1;
            } else if (myarry[i] == 'e') {
                count[4] = count[4] + 1;
            } else if (myarry[i] == 'f') {
                count[5] = count[5] + 1;
            } else if (myarry[i] == 'g') {
                count[6] = count[6] + 1;
            } else if (myarry[i] == 'h') {
                count[7] = count[7] + 1;
            } else if (myarry[i] == 'i') {
                count[8] = count[8] + 1;
            } else if (myarry[i] == 'j') {
                count[9] = count[9] + 1;
            } else if (myarry[i] == 'k') {
                count[10] = count[10] + 1;
            } else if (myarry[i] == 'l') {
                count[11] = count[11] + 1;
            } else if (myarry[i] == 'm') {
                count[12] = count[12] + 1;
            } else if (myarry[i] == 'n') {
                count[13] = count[13] + 1;
            } else if (myarry[i] == 'o') {
                count[14] = count[14] + 1;
            } else if (myarry[i] == 'p') {
                count[15] = count[15] + 1;
            } else if (myarry[i] == 'q') {
                count[16] = count[16] + 1;
            } else if (myarry[i] == 'r') {
                count[17] = count[17] + 1;
            } else if (myarry[i] == 's') {
                count[18] = count[18] + 1;
            } else if (myarry[i] == 't') {
                count[19] = count[19] + 1;
            } else if (myarry[i] == 'u') {
                count[20] = count[20] + 1;
            } else if (myarry[i] == 'v') {
                count[21] = count[21] + 1;
            } else if (myarry[i] == 'w') {
                count[22] = count[22] + 1;
            } else if (myarry[i] == 'x') {
                count[23] = count[23] + 1;
            } else if (myarry[i] == 'y') {
                count[24] = count[24] + 1;
            } else if (myarry[i] == 'z') {
                count[25] = count[25] + 1;
            }

        }



        for (int i = 0; i <count.length; i++) {
            totCount+=count[i];
        }

        System.out.println("tot "+ totCount);


       // calculate presentage
        for (int i = 0; i <count.length; i++) {
               precntage[i]=((count[i]/totCount)*100);
               precntage[i]=Math.round(precntage[i]);
        }




        char s1='A';
        System.out.println("Letter\tPrecentage\tFrequency");
        for (int i = 0; i < count.length; i++) {
            String gs=Character.toString(s1++);
            System.out.println(gs+"\t"+precntage[i]+"%"+"\t\t"+count[i]);
        }


    }

    String readFile(String fileName) throws IOException {
        BufferedReader buff = new BufferedReader(new FileReader(fileName));
        try {
            StringBuilder sb = new StringBuilder();
            String l = buff.readLine();

            while (l != null) {
                sb.append(l);
                sb.append("\n");
                l = buff.readLine();
            }
            return sb.toString();
        } finally {
            buff.close();
        }
    }

}

希望这会对你有所帮助。