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Feature - Shortest incomplete path
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- Although computationally expensive, I created a snapshot of the parents map everytime we hit a new node, to keep track of the shortest path in case we never hit all needed nodes
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@neozhixuan
neozhixuan committed Dec 4, 2023
1 parent 137e68f commit f2e5d42
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Showing 2 changed files with 4 additions and 55 deletions.
2 changes: 1 addition & 1 deletion client/components/map/FacilityCard.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ export const FacilityCard = ({
))}
</Flex>
<Text fontSize={"sm"} as={"b"}>
They also accept these items:
They generally accept items of these categories:
</Text>
<Flex gap={2} fontSize={"xs"} fontWeight={500} width={"100%"} wrap={"wrap"}>
{categoriesProcessor(facCardDetails.categoriesAccepted)}
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57 changes: 3 additions & 54 deletions client/utils.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -63,8 +63,6 @@ export const getNearbyFacilities = (
}
return false;
});
console.log("look here");
console.log(distances);
// Filter out nearest 5 bins specifically, and reinsert to relevant lists
const reducedBlueBinFacilities = blueBinFacilities
.sort((a, b) => {
Expand All @@ -87,8 +85,6 @@ export const getNearbyFacilities = (

return distA - distB;
});
console.log("look here");
console.log(distances);
res[catAndMethod] = {
facilities: relevantFacilities.map((facility) => ({
id: facility.id,
Expand Down Expand Up @@ -194,21 +190,12 @@ class PriorityQueue {
}

// Re-sort the queue based on the updated distance
console.log("this priority");
console.log((userCats.size / item.itemsCleared.size) * item.distance);
console.log("---");
this.queue.sort((a, b) => {
const aPriority = a.distance * (userCats.size / a.itemsCleared.size);
const bPriority = b.distance * (userCats.size / b.itemsCleared.size);

return aPriority - bPriority;
});
console.log("priority queue:");
for (const node of this.queue) {
console.log(node.distance * (userCats.size / node.itemsCleared.size));
}

console.log(JSON.stringify(this.queue));
}
dequeue() {
return this.queue.shift();
Expand Down Expand Up @@ -304,10 +291,8 @@ const dijkstra = (
address: AddressOption,
userCats: Set<[Categories, Methods]>,
): RecyclingLocationResults["route"] => {
// console.log(relevantFacilities);
// Create adjacency list
const adjList = constructAdjList(relevantFacilities, address, userCats);
console.log(adjList);
// Track parent of each node
const parentsMap = new Map<number, number>();
const visitedMap = new Map<number, number>();
Expand All @@ -317,28 +302,17 @@ const dijkstra = (
parentsMap.set(facility.id, -1);
visitedMap.set(facility.id, 0);
}
const itemSet = new Set<[Categories, Methods][]>();
// Create priority queue for finding optimum location using a Greedy heuristic
const priorityQueue = new PriorityQueue();
// Enqueue the user Node
priorityQueue.enqueue({ node: 123456, distance: 0, itemsCleared: new Set() }, userCats);
let furthestNode: PQEdge = { node: -1, distance: 0, itemsCleared: new Set() };
let parentsSnapshotMap = new Map<number, number>();

// Go through all the nearest nodes to you until you find a set of nodes that clear all your items
while (!priorityQueue.isEmpty()) {
// Dequeue the shortest node
const { node, distance, itemsCleared } = priorityQueue.dequeue() as PQEdge;
console.log("Dequeueing...");
const facility = relevantFacilities.find((facility) => facility.id === node);
if (facility) {
console.log(`Source node: ${facility.channelName}, ${node}`);
} else {
console.log(`Source node: User`);
}
console.log(JSON.stringify(priorityQueue));
for (const item of itemsCleared) {
console.log("Item: " + item[0] + " " + item[1]);
}

visitedMap.set(node, 1);

Expand Down Expand Up @@ -369,30 +343,14 @@ const dijkstra = (
// NORMAL FLOW: look through each neighbour
const currentNode = node;
for (const { nextNode, nextDistance, items } of adjList[currentNode]) {
console.log("Looking at neighbour:");
const facility = relevantFacilities.find((facility) => facility.id === nextNode);
if (facility) {
console.log(
`Neighbour node: ${facility.channelName}, ${nextNode}, total dist = ${
distance + nextDistance
}`,
);
}
const updatedItemsCleared = new Set(itemsCleared);
console.log(items);
// Track if a new item is added
if (items) {
for (const item of items) {
updatedItemsCleared.add(item);
}
}

// // ISSUE: If we have explored the nearest facility that is a Blue Bin, we do not want to explore other Blue Bins.
// if (itemSet.has(items)) {
// continue;
// } else {
// itemSet.add(items);
// }
const nextNodeOrigDistance = distanceMap.get(nextNode) as number;
const updatedDistance = distance + nextDistance;
// If it is not visited
Expand All @@ -403,31 +361,22 @@ const dijkstra = (
updatedItemsCleared.size > itemsCleared.size &&
updatedDistance < nextNodeOrigDistance
) {
// const facility = relevantFacilities.find((facility) => facility.id === node);
// if (facility) {
// console.log(`Considering node: ${facility.channelName}`);
// }
// FurthestNode is used to track the last node accessed, in the case of incomplete routing.
// Track the distances and parents of the newly updated ndoe
distanceMap.set(node, updatedDistance);
parentsMap.set(nextNode, currentNode);
// If the node is already in the PQ, update it - else, add it into the PQ. It will auto sort.
console.log("Enqueueing with updated items:");
console.log(updatedItemsCleared);
const pqEdge: PQEdge = {
node: nextNode,
distance: updatedDistance,
itemsCleared: updatedItemsCleared,
};
if (updatedItemsCleared.size > furthestNode.itemsCleared.size) {
console.log("you did it!");
console.log(updatedItemsCleared.size);
furthestNode = pqEdge;
parentsSnapshotMap = new Map([...parentsMap]);
}
priorityQueue.enqueue(pqEdge, userCats);
}
}
// console.log("Moving on to next");
}
// EDGE CASE: If there are no facilities that take your items
if (furthestNode.node === -1) {
Expand All @@ -438,7 +387,7 @@ const dijkstra = (
let backtrackNode: number = furthestNode.node;
while (backtrackNode !== 123456) {
path.unshift(backtrackNode);
backtrackNode = parentsMap.get(backtrackNode) as number;
backtrackNode = parentsSnapshotMap.get(backtrackNode) as number;
}
const distance = furthestNode.distance;
path.unshift(123456);
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