如何解决Linq Aggregate给出了空值，而不是预期的回报列表
我正在尝试使用linq聚合来模仿减少行为。我需要//We define a graph
class Node {
constructor() {
//hash map
this.connections = new Map()
//attributes
this.attributes = new Map()
}
}
class Graph {
constructor() {
//get nodes
this.nodes = new Node()
}
//Add node
addNode(node) {
this.nodes.connections.set(node,[])
this.nodes.attributes.set(node,[])
}
addNodeAttribute(node,attribute) {
//set a node attribute
this.nodes.attributes.get(node).push(attribute)
}
//Create an edge
addEdge(source,destination) {
//if A is friend with B,b is friends with A //undirected
this.nodes.connections.get(source).push(destination)
this.nodes.connections.get(destination).push(source)
}
breadthFirstSearch(startingNode) {
let visitednodes = []
let queue = []
visitednodes[startingNode] = true
queue.push(startingNode)
while (queue.length > 0) {
const currentNode = queue.shift() //takes the first element
const connections = this.nodes.connections.get(currentNode)
if (this.nodes.attributes.get(currentNode) == "Mango") {
return currentNode
}
for (let node of connections) {
if(!visitednodes[node]) { //if not visited
visitednodes[node] = true //then true
queue.push(node) //push node
}
}
}
return "no mango sellers"
}
}
let graph = new Graph()
//Create nodes
graph.addNode("Nicolai")
graph.addNode("Alice")
graph.addNode("Claire")
graph.addNode("Peggy")
graph.addNode("Bob")
graph.addNode("Anuj")
graph.addNode("Jonny")
graph.addNode("Thom")
//selling mangoer
graph.addNodeAttribute("Thom","Mango")
//add edeges
graph.addEdge("Nicolai","Bob")
graph.addEdge("Nicolai","Claire")
graph.addEdge("Nicolai","Alice")
graph.addEdge("Alice","Peggy")
graph.addEdge("Bob","Peggy" )
graph.addEdge("Bob","Anuj")
graph.addEdge("Claire","Thom")
graph.addEdge("Claire","Jonny")
console.log(graph.nodes.connections)
返回数组列表。出于某种原因，GroupingMethod无论如何都返回null。感谢您的帮助。
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