From a5884a68db40838fc8319a0bbcb8684b0e2d032d Mon Sep 17 00:00:00 2001
From: Michael Peters <michael@styx>
Date: Wed, 4 Sep 2024 20:32:53 -0700
Subject: [PATCH] exclude both sources and sinks from
 findAcyclicInternalNewConns

---
 src/site/snake/neat.ts | 15 +++++++--------
 src/site/snake/util.ts |  4 ++--
 src/test/test-neat.ts  | 12 ++++++------
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/site/snake/neat.ts b/src/site/snake/neat.ts
index e3b37a2..70391b2 100644
--- a/src/site/snake/neat.ts
+++ b/src/site/snake/neat.ts
@@ -229,7 +229,7 @@
  */
 
 import { edgesToNodes, NodeID, traceParents, RawEdge, traceChildren } from './network';
-import { keyMax, mapInvert, mapMap, randchoice, randint, randomNegPos, setDifference, setMap } from './util';
+import { keyMax, mapInvert, mapMap, randchoice, randint, randomNegPos, setDifference, setMap, setUnion } from './util';
 
 export interface GeneData {
     innovation: number;
@@ -548,19 +548,18 @@ export function findAcyclicInternalNewConns<DataT>(rawEdges: RawEdge<DataT>[]):
     const parents = traceParents(nodes);
     const children = traceChildren(nodes);
 
-    // TODO: exclude *both* sources and sinks
-    //       - sources are defined during think
-    //       - sinks should not be connected?  <-- they probably could be, but not clean imo
+    // exclude *both* sources and sinks
+    //     - sources are defined during think, connections will be ignored
+    //     - sinks should not be connected?  <-- they probably could be, but it would be unclean imo
     const sources = new Set(Array.from(parents.entries()).flatMap(([k, v]) => (v.size === 0 ? [k] : [])));
     const sinks = new Set(Array.from(children.entries()).flatMap(([k, v]) => (v.size === 0 ? [k] : [])));
 
     const acyclic = new Map<NodeID, Set<NodeID>>();
     for (const [nodeID, nodeParents] of parents.entries()) {
         const nodeParentIDs = setMap(nodeParents, n => n.id);
-        const nodeIDsAcyclic = setDifference(allNodeIDs, nodeParentIDs);
-        nodeIDsAcyclic.delete(nodeID);
-        const nodeIDsAcyclicNonSource = setDifference(nodeIDsAcyclic, sources);
-        acyclic.set(nodeID, nodeIDsAcyclicNonSource);
+        const exclude = setUnion(nodeParentIDs, sources, sinks, new Set([nodeID]));
+        const nodeIDsAcyclic = setDifference(allNodeIDs, exclude);
+        acyclic.set(nodeID, nodeIDsAcyclic);
     }
 
     // flatten
diff --git a/src/site/snake/util.ts b/src/site/snake/util.ts
index 75d83d3..506dd2c 100644
--- a/src/site/snake/util.ts
+++ b/src/site/snake/util.ts
@@ -46,7 +46,7 @@ export function mapMap<K1, V1, K2, V2>(m: Map<K1, V1>, mapper: (k: K1, v: V1) =>
     return new Map(Array.from(m.entries()).map(([k, v]) => mapper(k, v)));
 }
 
-export function setIntersection<T>(...sets: Set<T>[]) {
+export function setIntersection<T>(...sets: Set<T>[]): Set<T> {
     // a & b & ...
     if (sets.length === 0) return new Set();
     const intersection = new Set(sets[0]!);
@@ -56,7 +56,7 @@ export function setIntersection<T>(...sets: Set<T>[]) {
     return intersection;
 }
 
-export function setUnion<T>(...sets: Set<T>[]) {
+export function setUnion<T>(...sets: Set<T>[]): Set<T> {
     // a & b & ...
     if (sets.length === 0) return new Set();
     const union = new Set(sets[0]!);
diff --git a/src/test/test-neat.ts b/src/test/test-neat.ts
index 2e2d4bc..bedc89f 100644
--- a/src/test/test-neat.ts
+++ b/src/test/test-neat.ts
@@ -380,21 +380,21 @@ function testFindAcyclicInternalNewConns() {
     const options = findAcyclicInternalNewConns(edges);
     const expected = [
         // not A -> B - B is a source
-        { src_id: 'A', dst_id: 'F' },
+        // not A -> F - F is a sink
         // not B -> A - A is a source
         { src_id: 'B', dst_id: 'C' },
-        { src_id: 'B', dst_id: 'E' },
-        { src_id: 'B', dst_id: 'F' },
+        // not B -> E - E is a sink
+        // not B -> F - F is a sink
         // not C -> B - B is a source
         { src_id: 'C', dst_id: 'D' },
-        { src_id: 'C', dst_id: 'F' },
+        // not C -> F - F is a sink
         { src_id: 'D', dst_id: 'C' },
         // not E -> B - B is a parent of E
-        { src_id: 'E', dst_id: 'F' },
+        // not E -> F - F is a sink
         // not F -> A - A is a parent of F
         // not F -> B - B is a parent of F
         { src_id: 'F', dst_id: 'C' },
-        { src_id: 'F', dst_id: 'E' },
+        // not F -> E - E is a sink
     ];
 
     function strcmp(a: string, b: string) {