Bucket stats based on a start and end time

statsbucket.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/montanaflynn/stats"
)

const timeFormat = "15:04:05"

var windowSize = time.Minute

type window struct {
	started   int
	ongoing   int
	ended     int
	durations []float64
}

func main() {
	finFile := flag.String("in", "", "Input file")
	flag.Parse()

	if *finFile == "" {
		flag.Usage()
		return
	}

	file, err := os.Open(*finFile)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer file.Close()

	times := []time.Time{}
	windows := make(map[time.Time]*window)

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		beginend := strings.Split(scanner.Text(), " ")
		startTime, err := time.Parse(timeFormat, beginend[0])
		if err != nil {
			panic(err)
		}
		endTime, err := time.Parse(timeFormat, beginend[1])
		if err != nil {
			panic(err)
		}

		beginWindow := startTime.Truncate(windowSize)
		endWindow := endTime.Add(windowSize).Truncate(windowSize)

		for i := beginWindow; i.Before(endWindow); i = i.Add(windowSize) {
			if _, ok := windows[i]; !ok {
				times = append(times, i)
				windows[i] = &window{}
				windows[i].durations = []float64{}
			}
			if i == beginWindow {
				windows[i].durations = append(windows[i].durations, endTime.Sub(startTime).Seconds())
				windows[i].started++
			} else if i == endWindow {
				windows[i].ended++
			} else {
				windows[i].ongoing++
			}
		}
	}

	if err := scanner.Err(); err != nil {
		fmt.Println(err)
		return
	}

	for _, time := range times {
		bucket := windows[time]
		var max, min, stddev, mean float64
		if bucket.started > 0 {
			max, _ = stats.Max(bucket.durations)
			min, _ = stats.Min(bucket.durations)
			stddev, _ = stats.StandardDeviation(bucket.durations)
			mean, _ = stats.Mean(bucket.durations)
		}

		fmt.Printf("%s,%d,%d,%d,%f,%f,%f,%f\n",
			time.Format(timeFormat),
			bucket.started,
			bucket.ongoing,
			bucket.ended,
			min,
			max,
			mean,
			stddev)
	}
}