From e5fb663c5d9eba8dbd923e265faa603113369a34 Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Wed, 19 Feb 2020 17:47:25 +0000
Subject: [PATCH] Minor improvement of integrals for mixed distributions

---
 __tests__/Foo/Foo__Test.re                    | 27 ++++++------
 showcase/entries/Continuous.re                | 11 ++---
 .../charts/GenericDistributionChart.re        |  4 +-
 src/core/Shape.re                             | 41 +++++++++++--------
 4 files changed, 46 insertions(+), 37 deletions(-)

diff --git a/__tests__/Foo/Foo__Test.re b/__tests__/Foo/Foo__Test.re
index f2f1ad33..4f574267 100644
--- a/__tests__/Foo/Foo__Test.re
+++ b/__tests__/Foo/Foo__Test.re
@@ -6,21 +6,20 @@ let shape: DistributionTypes.xyShape = {
   ys: [|8., 9., 2.|],
 };
 
+let step: DistributionTypes.xyShape = {
+  xs: [|1., 4., 8.|],
+  ys: [|8., 17., 19.|],
+};
+
 open Shape;
 
 describe("Shape", () =>
-  describe("XYShape", () =>
-    test("#ySum", ()
-      =>
-        expect(XYShape.ySum(shape)) |> toEqual(19.0)
-      )
-      // test("#both", () => {
-      //   let expected: DistributionTypes.xyShape = {
-      //     xs: [|1., 4., 8.|],
-      //     ys: [|8., 1., 1.|],
-      //   };
-      //   expect(shape |> XYShape.derivative |> XYShape.integral)
-      //   |> toEqual(shape);
-      // });
-  )
+  describe("XYShape", () => {
+    test("#ySum", () =>
+      expect(XYShape.ySum(shape)) |> toEqual(19.0)
+    );
+    test("#yFOo", () =>
+      expect(Discrete.integrate(shape)) |> toEqual(step)
+    );
+  })
 );
\ No newline at end of file
diff --git a/showcase/entries/Continuous.re b/showcase/entries/Continuous.re
index f14b8a38..7eaec0b4 100644
--- a/showcase/entries/Continuous.re
+++ b/showcase/entries/Continuous.re
@@ -39,11 +39,12 @@ let domainLimitedDist =
 let distributions = () =>
   <div>
     <div>
-      <h2> {"Basic Mixed Distribution" |> ReasonReact.string} </h2>
-      <GenericDistributionChart dist=timeDist />
-      <h2> {"Simple Continuous" |> ReasonReact.string} </h2>
-      <GenericDistributionChart dist=mixedDist />
-    </div>
+
+        <h2> {"Basic Mixed Distribution" |> ReasonReact.string} </h2>
+        <GenericDistributionChart dist=timeDist />
+        <h2> {"Simple Continuous" |> ReasonReact.string} </h2>
+      </div>
+      // <GenericDistributionChart dist=mixedDist />
   </div>;
 // <div>
 //   <h2> {"Time Distribution" |> ReasonReact.string} </h2>
diff --git a/src/components/charts/GenericDistributionChart.re b/src/components/charts/GenericDistributionChart.re
index d40f2592..fa908216 100644
--- a/src/components/charts/GenericDistributionChart.re
+++ b/src/components/charts/GenericDistributionChart.re
@@ -20,7 +20,6 @@ module Mixed = {
         <thead>
           <tr>
             <th className="px-4 py-2"> {"X Point" |> ReasonReact.string} </th>
-            <th className="px-4 py-2"> {"Y Pount" |> ReasonReact.string} </th>
             <th className="px-4 py-2">
               {"Y Integral to Point" |> ReasonReact.string}
             </th>
@@ -41,6 +40,9 @@ module Mixed = {
         </tbody>
       </table>
       <div />
+      {data.discrete
+       |> Shape.Discrete.scaleYToTotal(data.discreteProbabilityMassFraction)
+       |> Shape.Discrete.render}
     </div>;
   };
 };
diff --git a/src/core/Shape.re b/src/core/Shape.re
index d70e1409..1c596cfd 100644
--- a/src/core/Shape.re
+++ b/src/core/Shape.re
@@ -17,6 +17,8 @@ module XYShape = {
     {"xs": t.xs, "ys": t.ys};
   };
 
+  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 scaleCdfTo = (~scaleTo=1., t: t) =>
@@ -84,8 +86,6 @@ module XYShape = {
 
     let mapYsBasedOnRanges = fn => inRanges(r => (nextX(r), fn(r)), toT);
 
-    let toStepFn = z => mapYsBasedOnRanges(rangeAreaAssumingSteps, z);
-
     let integrateWithSteps = z =>
       mapYsBasedOnRanges(rangeAreaAssumingSteps, z) |> E.O.fmap(accumulateYs);
 
@@ -142,23 +142,21 @@ module Discrete = {
        )
     |> ReasonReact.array;
 
-  let findY = (x: float, t: t) =>
-    switch (E.A.getBy(zip(t), ((ix, _)) => ix == x)) {
-    | Some((_, y)) => y
-    | None => 0.
-    };
-
   let integrate = XYShape.accumulateYs;
   let derivative = XYShape.subtractYs;
 
-  let findIntegralY = (f, t: t) =>
-    t
-    |> XYShape.Range.toStepFn
-    |> E.O.fmap(XYShape.accumulateYs)
-    |> E.O.fmap(CdfLibrary.Distribution.findY(f));
+  // TODO: This has a clear bug where it returns the Y value of the first item,
+  // even if X is less than the X of the first item.
+  let findIntegralY = (f, t: t) => {
+    t |> XYShape.accumulateYs |> CdfLibrary.Distribution.findY(f);
+  };
 
-  let findX = (f, t: t) =>
-    t |> XYShape.Range.toStepFn |> E.O.fmap(CdfLibrary.Distribution.findX(f));
+  let findY = (f, t: t) => {
+    Belt.Array.zip(t.xs, t.ys)
+    |> E.A.getBy(_, ((x, _)) => x == f)
+    |> E.O.fmap(((_, y)) => y)
+    |> E.O.default(0.);
+  };
 };
 
 module Mixed = {
@@ -195,7 +193,7 @@ module Mixed = {
     let c = t.continuous |> Continuous.findIntegralY(x);
     let d = Discrete.findIntegralY(x, t.discrete);
     switch (c, d) {
-    | (Some(c), Some(d)) => Some(mixedMultiply(t, c, d))
+    | (Some(c), d) => Some(mixedMultiply(t, c, d))
     | _ => None
     };
   };
@@ -208,13 +206,22 @@ module Mixed = {
 module Any = {
   type t = DistributionTypes.pointsType;
 
-  let x = (t: t, x: float) =>
+  let y = (t: t, x: float) =>
     switch (t) {
     | Mixed(m) => `mixed(Mixed.getY(m, x))
     | Discrete(discreteShape) => `discrete(Discrete.findY(x, discreteShape))
     | Continuous(continuousShape) =>
       `continuous(Continuous.findY(x, continuousShape))
     };
+
+  let yIntegral = (t: t, x: float) =>
+    switch (t) {
+    | Mixed(m) => `mixed(Mixed.getYIntegral(x, m))
+    | Discrete(discreteShape) =>
+      `discrete(Discrete.findIntegralY(x, discreteShape))
+    | Continuous(continuousShape) =>
+      `continuous(Continuous.findIntegralY(x, continuousShape))
+    };
 };
 
 module DomainMixed = {