fnv.example

fnv.go

package main

import (
	"bufio"
	"hash/fnv"
	"log"
	"os"
)

func main() {
	if len(os.Args) < 2 {
		log.Fatal("give me a file name")
	}
	file := os.Args[1]
	f, err := os.Open(file)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	s := bufio.NewScanner(f)

	distribution := make(map[uint32]int, 100)

	var total int
	for s.Scan() {
		in := s.Bytes()
		h := fnv.New32()
		h.Write(in)
		out := h.Sum32()

		distribution[out%100]++
		total++
	}

	var (
		maxK, minK uint32
		maxV, minV int
	)
	minV = 10021

	for k, v := range distribution {
		if v > maxV {
			maxV = v
			maxK = k
		}
		if v < minV {
			minV = v
			minK = k
		}

		log.Printf("%v: %v", k, v)
	}

	average := total / len(distribution)
	log.Printf("ave=%v", average)
	log.Printf("maxK=%v, maxV=%v minK=%v; minV=%v",
		maxK, maxV, minK, minV)
	log.Printf("[%f,%f]",
		float32((maxV-average))/float32(average),
		float32((minV-average))/float32(average),
	)

}