trigram-freq-merge.go

package main

import (
	"bufio"
	"fmt"
	"github.com/jessevdk/go-flags"
	"github.com/rs/zerolog/log"
	"os"
	"strconv"
	"strings"
)


type options struct {
	Help         bool   `short:"h" long:"help" description:"Show help message"`
	Input  		 string `short:"i" long:"input" default:"freq.txt" description:"File with trigrams and count seperated by space, new record on newline"`
	Output       string `short:"o" long:"output" default:"result.txt" description:"Output file with trigrams"`
}

type Cache struct {
	Data map[string]int
}

func (c *Cache) Init() {
	c.Data = make(map[string]int)
}

func (c *Cache) Update (trigram, count string) {
	cnt, err := strconv.Atoi(count)
	if err != nil {
		log.Warn().Msgf("Could not parse integer from %v", count)
		return
	}
	if _, ok := c.Data[trigram]; ok {
		c.Data[trigram] += cnt
	} else {
		c.Data[trigram] = cnt
	}
}

func main()  {
	var opts options
	p := flags.NewParser(&opts, flags.Default&^flags.HelpFlag)
	_, err := p.Parse()
	if err != nil {
		log.Fatal().Msgf("fail to parse args: %v", err)
	}

	if opts.Help {
		p.WriteHelp(os.Stdout)
		os.Exit(0)
	}

	c := Cache{}
	c.Init()

	input, err := os.Open(opts.Input)
	if err != nil {
		log.Fatal().Msgf("could not read file %s", opts.Input)
	}
	defer input.Close()

	out, err := os.Create(opts.Output)
	if err != nil {
		log.Fatal().Msgf("could not create output file %v", opts.Output)
	}
	defer out.Close()

	scanner := bufio.NewScanner(input)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		parsed := strings.Split(line, " ")
		log.Info().Msgf("parsed: %v", parsed)
		c.Update(parsed[1], parsed[0])
	}

	w := bufio.NewWriter(out)
	for trigram, count := range c.Data {
		w.WriteString(fmt.Sprintf("%s %d\n", trigram, count))
	}
	w.Flush()

}