Calculate Rating for Some Old Topcoder Marathon Match

main.go

package main

// author: Leonardone

// Marathon Match Rating Calculation
// community.topcoder.com/longcontest/?module=Static&d1=support&d2=ratings

import (
	"fmt"
	. "gitlab.com/neetsdkasu/tcutils/tcdatafeed"
	"math"
	"os"
	"strings"
)

var rdList = map[string]int64{
	"mm102":      17264,
	"mm103":      17309,
	"mm105":      17377,
	"tco18final": 17338,
}

func calcRatings(coders []*Result) {

	if len(coders) < 2 {
		return
	}

	numCoders := float64(len(coders))

	aveRating := 0.0
	for _, coder := range coders {
		aveRating += float64(coder.OldRating)
	}
	aveRating /= numCoders

	cf := 0.0
	{
		cf1 := 0.0
		cf2 := 0.0
		for _, coder := range coders {
			cf1 += math.Pow(float64(coder.OldVolatility), 2.0)
			cf2 += math.Pow(float64(coder.OldRating)-aveRating, 2.0)
		}
		cf1 /= numCoders
		cf2 /= numCoders - 1.0
		cf = math.Sqrt(cf1 + cf2)
	}

	eRanks := make([]float64, len(coders))
	ePerfs := make([]float64, len(coders))
	for i, coder1 := range coders {
		wp := 0.5
		for _, coder2 := range coders {
			tmp1 := float64(coder2.OldRating - coder1.OldRating)
			v1 := math.Pow(float64(coder1.OldVolatility), 2.0)
			v2 := math.Pow(float64(coder2.OldVolatility), 2.0)
			tmp2 := math.Sqrt(2.0 * (v1 + v2))
			wp += 0.5 * (math.Erf(tmp1/tmp2) + 1.0)
		}
		eRanks[i] = wp
		ePerfs[i] = -stdNorminv((eRanks[i] - 0.5) / numCoders)
	}

	aRanks := make([]float64, len(coders))
	aPerfs := make([]float64, len(coders))
	{
		rankSums := make([]int, coders[len(coders)-1].Placed+1)
		rankCounts := make([]int, len(rankSums))
		for i, coder := range coders {
			rankSums[coder.Placed] += i + 1
			rankCounts[coder.Placed]++
		}
		for i, coder := range coders {
			sum := float64(rankSums[coder.Placed])
			count := float64(rankCounts[coder.Placed])
			aRanks[i] = sum / count
			aPerfs[i] = -stdNorminv((aRanks[i] - 0.5) / numCoders)
		}
	}

	newRatings := make([]float64, len(coders))
	newVolatilities := make([]float64, len(coders))
	for i, coder := range coders {

		perfAs := float64(coder.OldRating) + cf*(aPerfs[i]-ePerfs[i])

		weight := 1.0/(1.0-(0.42/float64(coder.NumRatings)+0.18)) - 1.0
		if coder.OldRating > 2500 {
			weight *= 0.8
		} else if coder.OldRating >= 2000 {
			weight *= 0.9
		}

		Cap := 150.0 + 1500.0/float64(coder.NumRatings+1)

		newRatings[i] = math.Max(
			float64(coder.OldRating)-Cap,
			math.Min(
				float64(coder.OldRating)+Cap,
				(float64(coder.OldRating)+weight*perfAs)/(1.0+weight),
			))
		if coder.Placed == 1 && newRatings[i] <= float64(coder.OldRating) {
			newRatings[i] = float64(coder.OldRating + 1)
		}

		newVolatilities[i] = math.Sqrt(
			math.Pow(newRatings[i]-float64(coder.OldRating), 2.0)/weight +
				math.Pow(float64(coder.OldVolatility), 2.0)/(weight+1.0))
	}

	fmt.Println(fmt.Sprintf(
		"%-3s %-20s %-4s %-4s %-4s %-4s %-5s %-5s %-7s %-6s",
		"Pos", "Handle",
		"OldR", "OldV",
		"NewR", "NewV",
		"ARank", "ERank",
		"Rating", "Vol",
	))

	for i, coder := range coders {
		fmt.Println(fmt.Sprintf(
			"%3d %-20s %4d %4d %4d %4d %5.1f %5.1f %7.2f %6.2f",
			coder.Placed, coder.Handle,
			coder.OldRating, coder.OldVolatility,
			coder.NewRating, coder.NewVolatility,
			aRanks[i], eRanks[i],
			newRatings[i], newVolatilities[i],
		))
	}
}

func stdNorminv(p float64) float64 {
	return math.Sqrt2 * math.Erfinv(2.0*p-1.0)
}

func main() {

	if len(os.Args) != 2 {
		showUsage()
		return
	}
	name := strings.ToLower(os.Args[1])

	rd, ok := rdList[name]
	if !ok {
		fmt.Println("invalid arg:", os.Args[1])
		showUsage()
		return
	}

	round, err := GetRoundResults(rd)
	if err != nil {
		fmt.Println("## ERROR ##")
		fmt.Println(err.Error())
		os.Exit(1)
		return
	}

	coders := []*Result{}
	for _, res := range round.Results {
		if res.OldRating > 0 {
			coders = append(coders, res)
		}
	}

	calcRatings(coders)
}

func showUsage() {
	req := []interface{}{"    arg:"}
	for k := range rdList {
		req = append(req, k)
	}
	fmt.Println("usage:", os.Args[0], "<arg>")
	fmt.Println(req...)
}

mm102.txt

Pos Handle               OldR OldV NewR NewV ARank ERank Rating  Vol   
  1 wleite               2862  307 2891  291   1.0   1.6 2891.31 291.09
  2 H_a_s_h              2189  354 2264  358   2.0   6.2 2262.87 358.53
  3 hakomo               2638  503 2643  460   3.0   3.3 2643.05 460.63
  4 yowa                 2061  264 2100  255   4.0   7.2 2100.04 255.38
  5 my316g               1599  268 1727  339   5.0  17.2 1718.95 336.18
  6 alpha_virginis       1262  431 1430  509   6.0  26.2 1427.44 508.80
  7 sumoru               1718  258 1785  266   7.0  14.0 1783.93 265.78
  8 Rustyoldman          1466  227 1566  291   8.0  21.0 1566.06 290.81
  9 tashikani            1362  356 1478  393   9.0  23.9 1475.52 392.92
 10 ebicochineal         1690  224 1730  214  10.0  14.5 1728.50 214.43
 11 EvbCFfp1XB           2093  283 2057  270  11.0   6.8 2056.77 269.92
 12 windhunterSB         1772  353 1784  316  12.0  13.4 1783.74 316.61
 13 Kriii                1765  557 1784  489  13.0  15.0 1782.48 493.61
 14 eris_c               1616  164 1635  149  14.0  16.3 1634.77 149.66
 15 bigeye               1330  245 1425  263  15.0  25.0 1424.77 263.09
 16 okazaki              1856  277 1817  262  16.0  11.0 1817.42 261.87
 17 kruntuid             1319  307 1377  298  17.0  25.1 1375.80 298.11
 18 kosakkun             1862  382 1812  355  18.0  11.7 1813.37 355.24
 19 BCSEiny              1393  198 1422  187  19.0  23.2 1421.89 187.18
 20 tanzaku              1424  412 1439  372  20.0  22.2 1438.56 372.61
 21 gasin                1335  394 1366  345  21.0  24.5 1362.74 350.25
 22 shamal               1867  281 1774  305  22.0  10.8 1775.08 304.68
 23 iwashi31             1728  230 1660  247  23.0  13.6 1660.60 247.26
 25 fluffyowl            1225  328 1255  292  24.0  27.5 1252.87 294.78
 26 tobari               1254  385 1276  302  25.0  26.5 1267.87 334.28
 27 neetsdkasu           1342  215 1333  193  26.0  24.7 1333.23 193.79
 28 tamas.kenez          1732  380 1640  384  27.0  14.5 1640.14 384.22
 29 kishore_g84          1358  206 1333  193  28.0  24.3 1333.07 193.20
 30 Pag2                 1207  453 1195  409  29.0  27.3 1195.35 409.05
 31 michalkowalski        979  454 1005  386  30.0  32.2 1004.60 386.03
 32 pkhomchuk            1066  277 1073  243  31.0  31.8 1073.30 243.96
 33 AmAtUrECoDeR         1234  318 1182  281  32.0  27.4 1193.59 290.51
 34 PikokoLoko            769  360  811  326  33.0  36.7  810.93 325.92
 35 vi002                1487  192 1378  272  34.0  20.3 1380.05 271.57
 36 fal_rnd              1237  286 1163  284  35.0  27.4 1165.15 284.38
 37 r2d1                  586  353  626  326  36.0  39.1  625.84 325.86
 38 LLI_E_P_JI_O_K       1392  218 1264  308  37.0  23.2 1263.78 307.56
 39 banboooo044           973  454  878  399  38.0  32.3  877.87 399.23
 41 mcw1142              1112  168 1035  220  39.0  31.4 1035.48 219.53
 42 qiriskiz              799  259  750  245  40.0  37.0  749.66 245.32
 44 id                    310  272  330  249  41.0  41.8  329.77 248.85
 45 cwilkes               791  281  676  341  42.5  37.0  676.42 341.17
 45 onigiri              1021  672  814  704  42.5  29.8  821.52 704.02