auctionsim/main/main.go

package main

import (
	"encoding/csv"
	"flag"
	"fmt"
	"git.chromaticdragon.app/kistaro/auctionsim/auctionsim"
	"log"
	"math"
	"math/rand"
	"os"
	"strings"
)

var (
	bidders = flag.Int("b", 1000, "Number of bidders in each auction.")
	runs    = flag.Int("r", 1, "Number of auctions to run.")

	errorDev  = flag.Float64("d", 1.0, "Standard deviation of bidder irrationality.")
	errorMean = flag.Float64("m", 0.0, "Mean of bidder irrationality. Negative values represent a bias towards underbidding.")

	format = flag.String("f", "txt", "Output format: plain text (\"txt\") or CSV (\"csv\").")
)

func deltaStr(delta float64) string {
	if delta > 0 {
		return fmt.Sprintf("gained ¤%f", delta)
	}
	if delta < 0 {
		return fmt.Sprintf("lost ¤%f", -delta)
	}
	return "broken even"
}

func normalizeFormat() error {
	*format = strings.ToLower(*format)
	if *format == "txt" {
		return nil
	}
	if *format == "csv" {
		return nil
	}
	return fmt.Errorf("unrecognized format: %q", *format)
}

type emitter interface {
	Emit(*auctionsim.ResultSummary)
	Flush()
}

type textEmitter struct {
	notFirst bool
}

func (t *textEmitter) Emit(summary *auctionsim.ResultSummary) {
	if !t.notFirst {
		fmt.Println()
		fmt.Println("-----------------")
		fmt.Println()
		t.notFirst = true
	}
	fmt.Printf("The auction winner paid ¤%f. They have %s.\n", summary.Price, deltaStr(summary.WinnerProfit))
	fmt.Printf("The item was worth ¤%f to them.\n", summary.WinnerValue)
	fmt.Printf("They would have paid up to ¤%f for it.\n", summary.WinnerMaxBid)

	fmt.Println()
	if summary.LosersWithRegrets < 1 {
		fmt.Println("The item was not worth that to anybody.")
	} else {
		fmt.Printf("The item was worth that to %d bidders, who stopped bidding too soon.\n", summary.LosersWithRegrets)
	}

	fmt.Println()
	if summary.HighestValueRank > summary.Bidders {
		fmt.Println("Wow! It was infinitely beyond worthless to everybody.")
	} else {
		fmt.Printf("The bidder who would have gotten the most value was outbid by %d bidders.\n", summary.HighestValueRank-1)
		fmt.Printf("The item was worth at most ¤%f to them. Their maximum bid was ¤%f.\n", summary.HighestValue, summary.HighestValuatorBid)
		fmt.Printf("If they had paid the winning bid, they would have %s.\n", deltaStr(summary.MissedProfit))
		fmt.Printf("They valued it ¤%f more than the winning bidder.\n", summary.ValueDelta)
	}
}

func (*textEmitter) Flush() {}

type csvEmitter struct {
	w *csv.Writer
}

func (c *csvEmitter) Emit(summary *auctionsim.ResultSummary) {
	c.w.Write(summary.CSVRecord())
}

func (c *csvEmitter) Flush() {
	c.w.Flush()
}

func main() {
	flag.Parse()

	if err := normalizeFormat(); err != nil {
		log.Fatal(err)
	}

	e := emitter(&textEmitter{})
	if *format == "csv" {
		w := csv.NewWriter(os.Stdout)
		e = &csvEmitter{w}
		w.Write(auctionsim.ResultSummaryCSVHeader())
	}
	defer e.Flush()

	for i := 0; i < *runs; i++ {
		g := &auctionsim.BiddersFromDistributions{
			Values: auctionsim.NormalestDistribution(),
			Irrationalities: &auctionsim.NormalDistribution{
				Rand:   rand.New(rand.NewSource(int64(rand.Uint64()))),
				StdDev: *errorDev,
				Mean:   *errorMean,
			},
			Bankrolls: auctionsim.ConstDistribution(math.Inf(1)),
		}
		e.Emit(auctionsim.Summarize(auctionsim.RunAuctionVerbosely(
			&auctionsim.CappedBidderGenerator{
				G:   g,
				Lim: int64(*bidders),
			},
		)))
	}
}