simplify fermi.go again

README.md

@@ -193,11 +193,13 @@ Done:
 - [x] Make -n flag work
 - [x] Add flag to repeat input lines (useful when reading from files)
 - [x] Add percentages
+- [x] Consider adding an understanding of percentages
 
 To (possibly) do:
 
+- [ ] Consider implications of sampling strategy for operating variables in this case.
+- [ ] Document mixture distributions
 - [ ] Fix lognormal multiplication and division by 0 or < 0
-- [ ] Consider adding an understanding of percentages
 - [ ] With the -f command line option, the program doesn't read from stdin after finishing reading the file
 - [ ] Add functions. Now easier to do with an explicit representation of the stakc
 - [ ] Think about how to draw a histogram from samples

fermi.go

@@ -20,7 +20,6 @@ type Stack struct {
 }
 
 type Dist interface {
-	Samples() []float64
 	Sampler(int, sample.State) float64
 }
 
@@ -42,44 +41,22 @@ type FilledSamples struct {
 
 /* Dist interface functions */
 // https://go.dev/tour/methods/9
-func (p Scalar) Samples() []float64 {
-	xs := make([]float64, N_SAMPLES)
-	for i := 0; i < N_SAMPLES; i++ {
-		xs[i] = float64(p)
-	}
-	return xs
-}
 func (p Scalar) Sampler(i int, r sample.State) float64 {
 	return float64(p)
 }
 
-func (ln Lognormal) Samples() []float64 {
-	sampler := func(r sample.State) float64 { return sample.Sample_to(ln.low, ln.high, r) }
-	// Can't do parallel because then I'd have to await throughout the code
-	return sample.Sample_serially(sampler, N_SAMPLES)
-}
 func (ln Lognormal) Sampler(i int, r sample.State) float64 {
 	return sample.Sample_to(ln.low, ln.high, r)
 }
 
-func (beta Beta) Samples() []float64 {
-	sampler := func(r sample.State) float64 { return sample.Sample_beta(beta.a, beta.b, r) }
-	return sample.Sample_serially(sampler, N_SAMPLES)
-}
 func (beta Beta) Sampler(i int, r sample.State) float64 {
 	return sample.Sample_beta(beta.a, beta.b, r)
 }
 
-func (fs FilledSamples) Samples() []float64 {
-	return fs.xs
-}
 func (fs FilledSamples) Sampler(i int, r sample.State) float64 {
 	// This is a bit subtle, because sampling from FilledSamples randomly iteratively converges
 	// to something different than the initial distribution
 	// So instead we have an i parameter.
-	// Not sure how I feel about it
-	// n := len(fs.xs)
-	// i := sample.Sample_int(n, r)
 	return fs.xs[i]
 }
 
@@ -180,7 +157,7 @@ func printAndReturnErr(err_msg string) error {
 }
 
 func prettyPrintStats(dist Dist) {
-	xs := dist.Samples()
+	xs := sample.Sample_serially(dist.Sampler, N_SAMPLES)
 	n := len(xs)
 
 	mean := 0.0
@@ -221,8 +198,8 @@ func prettyPrintStats(dist Dist) {
 // Generic operations with samples
 func operateDistsAsSamples(dist1 Dist, dist2 Dist, op string) (Dist, error) {
 
-	xs := dist1.Samples()
-	ys := dist2.Samples()
+	xs := sample.Sample_serially(dist1.Sampler, N_SAMPLES)
+	ys := sample.Sample_serially(dist2.Sampler, N_SAMPLES)
 	zs := make([]float64, N_SAMPLES)
 
 	for i := 0; i < N_SAMPLES; i++ {
@@ -379,9 +356,7 @@ func parseMixture(words []string, vars map[string]Dist) (Dist, error) {
 		return nil, printAndReturnErr("Not a mixture. \nMixture syntax: \nmx x 2.5 y 8 z 10\ni.e.: mx var weight var2 weight2 ... var_n weight_n")
 	}
 
-	var dists []Dist
 	var fs []func(int, sample.State) float64
-	// var ss [][]float64
 	var weights []float64
 
 	for i, word := range words {
@@ -390,12 +365,8 @@ func parseMixture(words []string, vars map[string]Dist) (Dist, error) {
 			if !exists {
 				return nil, printAndReturnErr("Expected mixture variable but didn't get a variable. \nMixture syntax: \nmx x 2.5 y 8 z 10\ni.e.: mx var weight var2 weight2 ... var_n weight_n")
 			}
-			// samples := dist.Samples()
 			f := dist.Sampler
-			// Inefficient to draw N_SAMPLES for each of the distributions, but conceptually simpler.
-			dists = append(dists, dist)
 			fs = append(fs, f)
-			// ss = append(ss, samples)
 		} else {
 			weight, err := pretty.ParseFloat(word)
 			if err != nil {

sample/sample.go

@@ -149,11 +149,11 @@ func Sample_mixture_once(fs []func64, weights []float64, r State) float64 {
 
 }
 
-func Sample_serially(f func64, n_samples int) []float64 {
+func Sample_serially(f func64i, n_samples int) []float64 {
 	xs := make([]float64, n_samples)
 	// var global_state = rand.New(rand.NewPCG(uint64(1), uint64(2)))
 	for i := 0; i < n_samples; i++ {
-		xs[i] = f(global_state)
+		xs[i] = f(i, global_state)
 	}
 	return xs
 }