fermi/fermi.go

434 lines
12 KiB
Go

package main
import (
"bufio"
"errors"
"flag"
"fmt"
"git.nunosempere.com/NunoSempere/fermi/pretty"
"git.nunosempere.com/NunoSempere/fermi/sample"
"math"
"os"
"sort"
"strings"
)
/* Types and interfaces */
type Stack struct {
old_dist Dist
vars map[string]Dist
}
type Dist interface {
Samples() []float64
}
type Scalar float64
type Lognormal struct {
low float64
high float64
}
type Beta struct {
a float64
b float64
}
type FilledSamples struct {
xs []float64
}
/* 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 (ln Lognormal) Samples() []float64 {
sampler := func(r sample.Src) 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 (beta Beta) Samples() []float64 {
sampler := func(r sample.Src) float64 { return sample.Sample_beta(beta.a, beta.b, r) }
return sample.Sample_serially(sampler, N_SAMPLES)
}
func (fs FilledSamples) Samples() []float64 {
return fs.xs
}
/* Constants */
const HELP_MSG = " Operation | Variable assignment | Special\n" +
" Operation: operator operand\n" +
" operator: (empty) | * | / | + | -\n" +
" operand: scalar | lognormal | beta | variable\n" +
" lognormal: low high\n" +
" beta: beta alpha beta\n" +
" Variable assignment: =: variable_name\n" +
" Variable assignment and clear stack: =. variable_name\n" +
" Special: \n" +
" Comment: # this is a comment\n" +
" Clear stack: clear | c | .\n" +
" Print debug info: debug | d\n" +
" Print help message: help | h\n" +
" Start additional stack: operator (\n" +
" Return from additional stack )\n" +
" Exit: exit | e\n" +
" Examples: \n" +
" + 2\n" +
" / 2.5\n" +
" * 1 10 (interpreted as lognormal)\n" +
" + 1 10\n" +
" * beta 1 10\n" +
" 1 10 (multiplication taken as default operation)\n" +
" =: x\n" +
" .\n" +
" 1 100\n" +
" + x\n" +
" # this is a comment\n" +
" * 1 12 # this is an operation followed by a comment\n" +
" * (\n" +
" 1 10\n" +
" + beta 1 100\n" +
" )\n" +
" exit\n"
const NORMAL90CONFIDENCE = 1.6448536269514727
const INIT_DIST Scalar = Scalar(1)
var N_SAMPLES = 1_00_000
/* Printers */
func prettyPrintDist(dist Dist) {
switch v := dist.(type) {
case Lognormal:
fmt.Printf("=> ")
pretty.PrettyPrint2Floats(v.low, v.high)
fmt.Println()
case Beta:
fmt.Printf("=> beta ")
pretty.PrettyPrint2Floats(v.a, v.b)
fmt.Println()
case Scalar:
fmt.Printf("=> scalar ")
w := float64(v)
pretty.PrettyPrintFloat(w)
fmt.Println()
case FilledSamples:
sorted_xs := make([]float64, N_SAMPLES)
copy(sorted_xs, v.xs)
sort.Slice(sorted_xs, func(i, j int) bool {
return sorted_xs[i] < sorted_xs[j]
})
low := sorted_xs[N_SAMPLES/20]
high := sorted_xs[N_SAMPLES*19/20]
fmt.Printf("=> ")
pretty.PrettyPrint2Floats(low, high)
fmt.Printf(" (")
pretty.PrettyPrintInt(N_SAMPLES)
fmt.Printf(" samples)")
fmt.Println()
default:
fmt.Printf("%v\n", v)
}
}
func printAndReturnErr(err_msg string) error {
fmt.Println(err_msg)
fmt.Println(HELP_MSG)
return errors.New(err_msg)
}
/* Operations */
// Generic operations with samples
func operateDistsAsSamples(dist1 Dist, dist2 Dist, op string) (Dist, error) {
xs := dist1.Samples()
ys := dist2.Samples()
zs := make([]float64, N_SAMPLES)
for i := 0; i < N_SAMPLES; i++ {
switch op {
case "*":
zs[i] = xs[i] * ys[i]
case "/":
if ys[0] != 0 {
zs[i] = xs[i] / ys[i]
} else {
fmt.Println("Error: When dividing as samples, division by zero")
return nil, errors.New("Division by zero")
}
case "+":
zs[i] = xs[i] + ys[i]
case "-":
zs[i] = xs[i] - ys[i]
}
}
return FilledSamples{xs: zs}, nil
}
// Multiplication
func multiplyLogDists(l1 Lognormal, l2 Lognormal) Lognormal {
logmean1 := (math.Log(l1.high) + math.Log(l1.low)) / 2.0
logstd1 := (math.Log(l1.high) - math.Log(l1.low)) / (2.0 * NORMAL90CONFIDENCE)
logmean2 := (math.Log(l2.high) + math.Log(l2.low)) / 2.0
logstd2 := (math.Log(l2.high) - math.Log(l2.low)) / (2.0 * NORMAL90CONFIDENCE)
logmean_product := logmean1 + logmean2
logstd_product := math.Sqrt(logstd1*logstd1 + logstd2*logstd2)
h := logstd_product * NORMAL90CONFIDENCE
loglow := logmean_product - h
loghigh := logmean_product + h
return Lognormal{low: math.Exp(loglow), high: math.Exp(loghigh)}
}
func multiplyBetaDists(beta1 Beta, beta2 Beta) Beta {
return Beta{a: beta1.a + beta2.a, b: beta1.b + beta2.b}
}
func multiplyDists(old_dist Dist, new_dist Dist) (Dist, error) {
switch o := old_dist.(type) {
case Lognormal:
{
switch n := new_dist.(type) {
case Lognormal:
return multiplyLogDists(o, n), nil
case Scalar:
return multiplyLogDists(o, Lognormal{low: float64(n), high: float64(n)}), nil
default:
return operateDistsAsSamples(old_dist, new_dist, "*")
}
}
case Scalar:
{
if o == 1 {
return new_dist, nil
}
switch n := new_dist.(type) {
case Lognormal:
return multiplyLogDists(Lognormal{low: float64(o), high: float64(o)}, n), nil
case Scalar:
return Scalar(float64(o) * float64(n)), nil
default:
return operateDistsAsSamples(old_dist, new_dist, "*")
}
}
case Beta:
switch n := new_dist.(type) {
case Beta:
return multiplyBetaDists(o, n), nil
default:
return operateDistsAsSamples(old_dist, new_dist, "*")
}
default:
return operateDistsAsSamples(old_dist, new_dist, "*")
}
}
func divideDists(old_dist Dist, new_dist Dist) (Dist, error) {
switch o := old_dist.(type) {
case Lognormal:
{
switch n := new_dist.(type) {
case Lognormal:
if n.high == 0 || n.low == 0 {
fmt.Println("Error: Can't divide by 0.0")
return nil, errors.New("Error: division by zero")
}
return multiplyLogDists(o, Lognormal{low: 1.0 / n.high, high: 1.0 / n.low}), nil
case Scalar:
if n == 0.0 {
fmt.Println("Error: Can't divide by 0.0")
return nil, errors.New("Error: division by zero scalar")
}
return multiplyLogDists(o, Lognormal{low: 1.0 / float64(n), high: 1.0 / float64(n)}), nil
default:
return operateDistsAsSamples(old_dist, new_dist, "/")
}
}
case Scalar:
{
switch n := new_dist.(type) {
case Lognormal:
return multiplyLogDists(Lognormal{low: float64(o), high: float64(o)}, Lognormal{low: 1.0 / n.high, high: 1.0 / n.low}), nil
case Scalar:
if n == 0.0 {
fmt.Println("Error: Can't divide by 0.0")
return nil, errors.New("Error: division by zero scalar")
}
return Scalar(float64(o) / float64(n)), nil
default:
return operateDistsAsSamples(old_dist, new_dist, "/")
}
}
default:
return operateDistsAsSamples(old_dist, new_dist, "/")
}
}
// Generic distribution operations
func operateDists(old_dist Dist, new_dist Dist, op string) (Dist, error) {
switch op {
case "*":
return multiplyDists(old_dist, new_dist)
case "/":
return divideDists(old_dist, new_dist)
case "+":
return operateDistsAsSamples(old_dist, new_dist, "+")
case "-":
return operateDistsAsSamples(old_dist, new_dist, "-")
default:
return nil, printAndReturnErr("Can't combine distributions in this way")
}
}
/* Parser and repl */
func parseWordsErr(err_msg string) (string, Dist, error) {
return "", nil, printAndReturnErr(err_msg)
}
func parseWordsIntoOpAndDist(words []string, vars map[string]Dist) (string, Dist, error) {
op := ""
var dist Dist
switch words[0] {
case "*", "/", "+", "-":
op = words[0]
words = words[1:]
default:
op = "*" // later, change the below to
}
switch len(words) {
case 0:
return parseWordsErr("Operator must have operand; can't operate on nothing")
case 1:
var_word, var_word_exists := vars[words[0]]
single_float, err1 := pretty.ParseFloat(words[0]) // abstract this away to search for K/M/B/T/etc.
switch {
case var_word_exists:
dist = var_word
case err1 == nil:
dist = Scalar(single_float)
case err1 != nil && !var_word_exists:
return parseWordsErr("Trying to operate on a scalar, but scalar is neither a float nor an assigned variable")
}
case 2:
new_low, err1 := pretty.ParseFloat(words[0])
new_high, err2 := pretty.ParseFloat(words[1])
if err1 != nil || err2 != nil {
return parseWordsErr("Trying to operate by a distribution, but distribution is not specified as two floats")
}
dist = Lognormal{low: new_low, high: new_high}
case 3:
if words[0] == "beta" || words[0] == "b" {
a, err1 := pretty.ParseFloat(words[1])
b, err2 := pretty.ParseFloat(words[2])
if err1 != nil || err2 != nil {
return parseWordsErr("Trying to specify a beta distribution? Try beta 1 2")
}
dist = Beta{a: a, b: b}
} else {
return parseWordsErr("Input not understood or not implemented yet")
}
default:
return parseWordsErr("Input not understood or not implemented yet")
}
return op, dist, nil
}
/* Combine old dist and new line */
// We want this as a function (rather than just be in main)
// to be able to have parenthesis/recusion, possibly functions
func runRepl(stack Stack, reader *bufio.Reader) Stack {
replForLoop:
for {
new_line, _ := reader.ReadString('\n')
new_line_before_comments, _, _ := strings.Cut(new_line, "#")
new_line_trimmed := strings.TrimSpace(new_line_before_comments)
words := strings.Split(new_line_trimmed, " ")
switch {
case strings.TrimSpace(new_line_trimmed) == "": /* Empty line case */
continue replForLoop
/* Parenthesis */
case len(words) == 2 && (words[0] == "*" || words[0] == "+" || words[0] == "-" || words[0] == "/") && words[1] == "(":
new_stack := runRepl(Stack{old_dist: INIT_DIST, vars: stack.vars}, reader)
combined_dist, err := operateDists(stack.old_dist, new_stack.old_dist, words[0])
if err == nil {
stack.old_dist = combined_dist
}
case len(words) == 1 && words[0] == ")":
return stack
/* Special operations */
case words[0] == "exit" || words[0] == "e":
os.Exit(0)
case words[0] == "help" || words[0] == "h":
fmt.Println(HELP_MSG)
case words[0] == "debug" || words[0] == "d":
fmt.Printf("%v", stack)
case words[0] == "clear" || words[0] == "c" || words[0] == ".":
stack.old_dist = INIT_DIST
fmt.Println()
/* Variable assignment */
case words[0] == "=:" && len(words) == 2:
stack.vars[words[1]] = stack.old_dist
fmt.Printf("%s ", words[1])
case words[0] == "=." && len(words) == 2:
stack.vars[words[1]] = stack.old_dist
fmt.Printf("%s ", words[1])
prettyPrintDist(stack.old_dist)
stack.old_dist = INIT_DIST
default:
op, new_dist, err := parseWordsIntoOpAndDist(words, stack.vars)
if err != nil {
continue replForLoop
}
combined_dist, err := operateDists(stack.old_dist, new_dist, op)
if err == nil {
stack.old_dist = combined_dist
}
}
prettyPrintDist(stack.old_dist)
}
}
func main() {
num_samples_flag := flag.Int("n", N_SAMPLES, "Specifies the number of samples to draw when using samples")
N_SAMPLES = *num_samples_flag
filename := flag.String("f", "", "Specifies a file with a model to run")
flag.Parse()
var reader *bufio.Reader = nil
if *filename != "" {
file, err := os.Open(*filename)
if err == nil {
reader = bufio.NewReader(file)
} else {
fmt.Printf("Error opening filename; reading from stdin instead\n")
}
}
if reader == nil {
reader = bufio.NewReader(os.Stdin)
}
stack := Stack{old_dist: INIT_DIST, vars: make(map[string]Dist)}
runRepl(stack, reader)
}