Fixed some discrete functions

__tests__/Foo/Foo__Test.re

@@ -49,35 +49,46 @@ describe("Shape", () => {
 
   describe("Discrete", () => {
     open Distributions.Discrete;
-    let shape: DistTypes.xyShape = {xs: [|1., 4., 8.|], ys: [|8., 9., 2.|]};
+    let shape: DistTypes.xyShape = {
+      xs: [|1., 4., 8.|],
+      ys: [|0.3, 0.5, 0.2|],
+    };
     let discrete = shape;
     makeTest("minX", T.minX(discrete), Some(1.0));
     makeTest("maxX", T.maxX(discrete), Some(8.0));
     makeTest(
       "pointwiseFmap",
       T.pointwiseFmap(r => r *. 2.0, discrete) |> (r => r.ys),
-      [|16., 18.0, 4.0|],
+      [|0.6, 1.0, 0.4|],
     );
     makeTest(
       "xToY at 4.0",
       T.xToY(4., discrete),
-      {discrete: 9.0, continuous: 0.0},
+      {discrete: 0.5, continuous: 0.0},
     );
     makeTest(
       "xToY at 0.0",
       T.xToY(0., discrete),
-      {discrete: 8.0, continuous: 0.0},
+      {discrete: 0.0, continuous: 0.0},
     );
     makeTest(
       "xToY at 5.0",
       T.xToY(5., discrete),
-      {discrete: 7.25, continuous: 0.0},
+      {discrete: 0.0, continuous: 0.0},
+    );
+    makeTest(
+      "integral",
+      T.Integral.get(~cache=None, discrete),
+      Distributions.Continuous.make(
+        {xs: [|1., 4., 8.|], ys: [|0.3, 0.8, 1.0|]},
+        `Stepwise,
+      ),
     );
     makeTest(
       "integralXToY",
-      T.Integral.xToY(~cache=None, 2.0, discrete),
-      11.0,
+      T.Integral.xToY(~cache=None, 6.0, discrete),
+      0.9,
     );
-    makeTest("integralSum", T.Integral.sum(~cache=None, discrete), 19.0);
+    makeTest("integralSum", T.Integral.sum(~cache=None, discrete), 1.0);
   });
 });

src/distributions/Distributions.re

@@ -122,6 +122,8 @@ module Continuous = {
     });
 };
 
+//  |> XYShape.Range.stepsToContinuous
+//  |> E.O.toExt("ERROR"),
 module Discrete = {
   module T =
     Dist({
@@ -133,12 +135,7 @@ module Discrete = {
         cache
         |> E.O.default(
              {
-               Continuous.make(
-                 XYShape.accumulateYs(t)
-                 |> XYShape.Range.stepsToContinuous
-                 |> E.O.toExt("ERROR"),
-                 `Stepwise,
-               );
+               Continuous.make(XYShape.accumulateYs(t), `Stepwise);
              },
            );
       //  todo: Fix this with last element
@@ -151,13 +148,19 @@ module Discrete = {
       let toDiscrete = t => Some(t);
       let toScaledContinuous = _ => None;
       let toScaledDiscrete = t => Some(t);
-      //  todo: Fix this with code that work find recent value and use that instead.
-      let xToY = (f, t) =>
-        CdfLibrary.Distribution.findY(f, t)
+
+      let xToY = (f, t) => {
+        XYShape.getBy(t, ((x, _)) => x == f)
+        |> E.O.fmap(((_, y)) => y)
+        |> E.O.default(0.0)
         |> DistTypes.MixedPoint.makeDiscrete;
+      };
       //  todo: This should use cache and/or same code as above. FindingY is more complex, should use interpolationType.
       let integralXtoY = (~cache, f, t) =>
-        t |> XYShape.accumulateYs |> CdfLibrary.Distribution.findY(f);
+        t
+        |> integral(~cache)
+        |> Continuous.getShape
+        |> CdfLibrary.Distribution.findY(f);
     });
 };
 

src/distributions/XYShape.re

@@ -1,29 +1,31 @@
 open DistTypes;
-let _lastElement = (a: array('a)) =>
-  switch (Belt.Array.size(a)) {
-  | 0 => None
-  | n => Belt.Array.get(a, n - 1)
-  };
 
 type t = xyShape;
 
 let toJs = (t: t) => {
   {"xs": t.xs, "ys": t.ys};
 };
-
-let minX = (t: t) => t.xs |> E.A.get(_, 0);
-// TODO: Check if this actually gets the last element, I'm not sure it does.
-let maxX = (t: t) => t.xs |> (r => E.A.get(r, E.A.length(r) - 1));
+let minX = (t: t) => t.xs |> E.A.first;
+let maxX = (t: t) => t.xs |> E.A.last;
+let first = (t: t) =>
+  switch (t.xs |> E.A.first, t.ys |> E.A.first) {
+  | (Some(x), Some(y)) => Some((x, y))
+  | _ => None
+  };
+let last = (t: t) =>
+  switch (t.xs |> E.A.last, t.ys |> E.A.last) {
+  | (Some(x), Some(y)) => Some((x, y))
+  | _ => None
+  };
 
 let zip = t => Belt.Array.zip(t.xs, t.ys);
-
-let fmap = (t: t, y): t => {xs: t.xs, ys: t.ys |> E.A.fmap(y)};
-
+let getBy = (t: t, fn) => t |> zip |> Belt.Array.getBy(_, fn);
+let pointwiseMap = (fn, t: t): t => {xs: t.xs, ys: t.ys |> E.A.fmap(fn)};
 let fromArray = ((xs, ys)): t => {xs, ys};
 let fromArrays = (xs, ys): t => {xs, ys};
-let pointwiseMap = (fn, t: t): t => {xs: t.xs, ys: t.ys |> E.A.fmap(fn)};
 
-let compare = (a: float, b: float) => a > b ? 1 : (-1);
+// todo: maybe not needed?
+// let comparePoint = (a: float, b: float) => a > b ? 1 : (-1);
 
 let comparePoints = ((x1: float, y1: float), (x2: float, y2: float)) =>
   switch (x1 == x2, y1 == y2) {
@@ -32,6 +34,7 @@ let comparePoints = ((x1: float, y1: float), (x2: float, y2: float)) =>
   | (true, true) => (-1)
   };
 
+// todo: This is broken :(
 let combine = (t1: t, t2: t) => {
   let totalLength = E.A.length(t1.xs) + E.A.length(t2.xs);
   let array = Belt.Array.concat(zip(t1), zip(t2));
@@ -53,14 +56,6 @@ let intersperce = (t1: t, t2: t) => {
   items^ |> Belt.Array.unzip |> fromArray;
 };
 
-let scaleCdfTo = (~scaleTo=1., t: t) =>
-  switch (_lastElement(t.ys)) {
-  | Some(n) =>
-    let scaleBy = scaleTo /. n;
-    fmap(t, r => r *. scaleBy);
-  | None => t
-  };
-
 let yFold = (fn, t: t) => {
   E.A.fold_left(fn, 0., t.ys);
 };
@@ -69,9 +64,8 @@ let ySum = yFold((a, b) => a +. b);
 
 let _transverse = fn =>
   Belt.Array.reduce(_, [||], (items, (x, y)) =>
-    switch (_lastElement(items)) {
-    | Some((xLast, yLast)) =>
-      Belt.Array.concat(items, [|(x, fn(y, yLast))|])
+    switch (E.A.last(items)) {
+    | Some((_, yLast)) => Belt.Array.concat(items, [|(x, fn(y, yLast))|])
     | None => [|(x, y)|]
     }
   );
@@ -89,6 +83,7 @@ let subtractYs = _transverseShape((aCurrent, aLast) => aCurrent -. aLast);
 let findY = CdfLibrary.Distribution.findY;
 let findX = CdfLibrary.Distribution.findX;
 
+// I'm really not sure this part is actually what we want at this point.
 module Range = {
   // ((lastX, lastY), (nextX, nextY))
   type zippedRange = ((float, float), (float, float));

src/utility/E.re

@@ -122,7 +122,7 @@ module R = {
 };
 
 let safe_fn_of_string = (fn, s: string): option('a) =>
-  try (Some(fn(s))) {
+  try(Some(fn(s))) {
   | _ => None
   };
 
@@ -216,6 +216,8 @@ module A = {
   let unsafe_get = Array.unsafe_get;
   let get = Belt.Array.get;
   let getBy = Belt.Array.getBy;
+  let last = a => get(a, length(a) - 1);
+  let first = get(_, 0);
   let hasBy = (r, fn) => Belt.Array.getBy(r, fn) |> O.isSome;
   let fold_left = Array.fold_left;
   let fold_right = Array.fold_right;
@@ -294,28 +296,4 @@ module JsArray = {
          Rationale.Option.toExn("Warning: This should not have happened"),
        );
   let filter = Js.Array.filter;
-};
-
-module NonZeroInt = {
-  type t = int;
-  let make = (i: int) => i < 0 ? None : Some(i);
-  let fmap = (fn, a: t) => make(fn(a));
-  let increment = fmap(I.increment);
-  let decrement = fmap(I.decrement);
-};
-
-module BoundedInt = {
-  type t = int;
-  let make = (i: int, limit: int) => {
-    let lessThan0 = r => r < 0;
-    let greaterThanLimit = r => r > limit;
-    if (lessThan0(i) || greaterThanLimit(i)) {
-      None;
-    } else {
-      Some(i);
-    };
-  };
-  let fmap = (fn, a: t, l) => make(fn(a), l);
-  let increment = fmap(I.increment);
-  let decrement = fmap(I.decrement);
 };