搜索引擎PageRank作业代码

pageRank.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"
)

var (
	alpha       *float64
	times       *int
	graphFile   *string
	nodeMapFile *string
	outFile     *string
	num         int

	pRank   map[int]float64
	nodeMap map[int]string
	linkMap map[int][]int
)

func parseFlag() {
	alpha = flag.Float64("alpha", 0.2, "参数α")
	times = flag.Int("m", 25, "迭代次数")
	graphFile = flag.String("wiki", "wiki.graph", "连接关系记录D") //wikigraphHead.txt
	nodeMapFile = flag.String("node", "node.map.utf8", "node.map.utf8")
	outFile = flag.String("output", "result.txt", "PageRank结果输出文件")

	flag.Parse()
	if flag.NFlag() == 0 {
		flag.PrintDefaults()
	}
}

func loadGraph() {
	f, err := os.Open(*nodeMapFile)
	if err != nil {
		fmt.Println(err)
		os.Exit(0)
	}
	defer f.Close()
	br := bufio.NewReader(f)

	nodeMap = make(map[int]string)
	linkMap = make(map[int][]int)
	var index, value int
	var name string
	for {
		line, err := br.ReadString('\n')
		if err == io.EOF {
			break
		} else {
			index = strings.Index(line, "-->")
			name = line[:index]
			value, err = strconv.Atoi(line[index+3 : len(line)-1])
			nodeMap[value] = name
			linkMap[value] = make([]int, 0)
		}
	}
	num = len(nodeMap)
	fmt.Println(num)

	f, err = os.Open(*graphFile)
	if err != nil {
		fmt.Println(err)
		os.Exit(0)
	}
	defer f.Close()
	br = bufio.NewReader(f)

	var outs []string
	for {
		line, err := br.ReadString('\n')
		if err == io.EOF {
			break
		} else {
			index = strings.Index(line, ":")
			value, err = strconv.Atoi(line[:index])
			outs = strings.Split(line[index+1:len(line)-1], ",") //末尾换行符去掉
			for i := 0; i < len(outs); i++ {
				out, _ := strconv.Atoi(outs[i])
				/*isnew := true
				for j := 0; j < len(linkMap[value]); j++ {
					if out == linkMap[value][j] {
						isnew = false
						break
					}
				}
				if isnew {*/
				linkMap[value] = append(linkMap[value], out)
				//}
			}
		}
	}
	fmt.Println("links format over")

}

func rank() {
	iTmp := make(map[int]float64)
	pRank = make(map[int]float64)
	s0Tmp, s1Tmp := 0.0, 0.0
	f1 := 1.0 / float64(num)
	f2 := *alpha / float64(num)
	for k := range nodeMap {
		iTmp[k] = f2
		pRank[k] = f1
		if len(linkMap[k]) == 0 { //outdegree
			s1Tmp += pRank[k]
		}
	}

	for k := 0; k < *times; k++ {
		//遍历每条链接关系
		for node, value := range linkMap {
			outdegree := len(value)
			for i := 0; i < outdegree; i++ {
				iTmp[value[i]] += (1.0 - *alpha) * pRank[node] / float64(outdegree)
			}
		}
		s0Tmp, s1Tmp = s1Tmp, 0.0
		for n := range pRank {
			pRank[n] = iTmp[n] + (1.0-*alpha)*s0Tmp/float64(num)
			iTmp[n] = f2
			if len(linkMap[n]) == 0 { //outdegree
				s1Tmp += pRank[n]
			}
		}
	}
	fmt.Println("rank over")
}

func output() {
	f, err := os.Create(*outFile)
	if err != nil {
		fmt.Println(err)
		os.Exit(0)
	}
	defer f.Close()

	bw := bufio.NewWriter(f)
	for k, v := range pRank {
		bw.WriteString(fmt.Sprintf("%.8d:%.20f:%s\n", k, v, nodeMap[k]))
	}
	bw.Flush()
}

func main() {
	parseFlag()
	loadGraph()
	rank()
	output()
}