103 lines
2.1 KiB
Go
103 lines
2.1 KiB
Go
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package shuffle
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import (
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"crypto/rand"
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"fmt"
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"log"
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"math/big"
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)
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const (
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n = 5
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samplesNum = 300000
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)
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func factorial(n int) *big.Int {
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return factorial_body(n, big.NewInt(1))
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}
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func factorial_body(n int, acc *big.Int) *big.Int {
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if n == 0 {
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return acc
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}
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acc.Mul(acc, big.NewInt(int64(n)))
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return factorial_body(n-1, acc)
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}
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func ChiSquare(obs, exp []float64) (float64, error) {
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if len(obs) != len(exp) {
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return 0, BENCHMARK_LEN_DN_MATCH
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}
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var result float64
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result = 0
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for i, a := range obs {
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b := exp[i]
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if a == 0 && b == 0 {
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continue
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}
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result += (a - b) * (a - b) / b
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}
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return result, nil
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}
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func bigChiSquare(observed []int, expected *big.Float) *big.Float {
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chiSquare := big.NewFloat(0)
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for _, obs := range observed {
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obsFloat := big.NewFloat(float64(obs))
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diff := new(big.Float).Sub(obsFloat, expected)
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squaredDiff := new(big.Float).Mul(diff, diff)
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term := new(big.Float).Quo(squaredDiff, expected)
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chiSquare.Add(chiSquare, term)
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}
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return chiSquare
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}
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func GetBenchmarkN() int {
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return n
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}
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func GetBenchmarkForShuffle[T Numeric](alg ShuffleNumericAlg[T], keyLen int, fullDebug bool) error {
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perms := map[[n]T]int{}
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for i := 0; i < samplesNum; i++ {
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if fullDebug {
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log.Printf("Running %d sample\n", i)
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}
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arr := [n]T{zeroValue[T]()}
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for i := 0; i < n; i++ {
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arr[i] = T(i)
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}
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//
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dummyKey := make([]byte, keyLen)
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keyN, err := rand.Read(dummyKey)
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if err != nil {
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return err
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}
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if keyN != len(dummyKey) {
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return BENCHMARK_INTERNAL_ERROR
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}
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alg(arr[:], dummyKey)
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//
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perms[arr]++
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}
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fact := factorial(n)
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factFloat := new(big.Float).SetInt(fact)
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// Calculate expected value
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samplesFloat := big.NewFloat(float64(samplesNum))
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expectedBig := new(big.Float).Quo(samplesFloat, factFloat)
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if fullDebug {
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log.Printf("expectedBig is %f\n", expectedBig)
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log.Printf("factorial is %d\n", factorial(n))
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}
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observed := make([]int, 0, len(perms))
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for _, count := range perms {
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// log.Printf("Getting count from perm = %d\n", count)
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observed = append(observed, count)
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}
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val := bigChiSquare(observed, expectedBig)
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fmt.Printf("Chi-Square value: %s\n", val.Text('f', 10))
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return nil
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}
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