增强XML解析的复杂性-C#XML循环 [英] Enhance XML Parsing complexity - c# XML Looping

问题描述

我正在编写自己的c#自定义地图导航程序.我正在使用 OpenStreetMaps 作为地图数据.这是一个大型XML文件，其中包含节点和方式.我写了一个转换器，将XML文件从无用的垃圾中删除(例如时间戳，用户等)，以使文件变小.

I am writing my own c# custom map navigation program. I am using OpenStreetMaps for the map data. It's a large XML file that contains Nodes and ways. I wrote a convertor that strips the XML file from useless junk (like timestamp, user etc) so the file will become smaller.

现在，当我尝试遍历XML并将数据转换为C#对象的方式和节点时，遇到了一个问题.我需要做很多循环，以至于加载时间太长.

Now while I attempt to loop through the XML and convert the data to C# object Ways and Nodes I came across a problem. I need to do so much looping that the loading time is way too long.

XML示例(w =方式，n =节点，rf =引用节点):

      <n id="2638006578" l="5.9295547" b="52.5619519" />
      <n id="2638006579" l="5.9301973" b="52.5619526" />
      <n id="2638006581" l="5.9303625" b="52.5619565" />
      <n id="2638006583" l="5.9389539" b="52.5619577" />
      <n id="2638006589" l="5.9386643" b="52.5619733" />
      <n id="2638006590" l="5.9296231" b="52.5619760" />
      <n id="2638006595" l="5.9358987" b="52.5619864" />
      <n id="2638006596" l="5.9335913" b="52.5619865" />
      <w id="453071384">
        <nd rf="2638006581" />
        <nd rf="2638006590" />
        <nd rf="2638006596" />
        <nd rf="2638006583" />
        <nd rf="2638006578" />
      </w>
      <w id="453071385">
        <nd rf="2638006596" />
        <nd rf="2638006578" />
        <nd rf="2638006581" />
        <nd rf="2638006583" />
      </w>

• 方式"节点包含对节点的引用，因此一个节点可以多种方式存在(节点连接方式).

  • The Way nodes contain references to nodes, so a node can be existent in multiple ways (the nodes connect the ways).

    节点包含经度和纬度(l = lon，b = lat).

    nodes contain a longitude and latitude (l = lon, b = lat).

    这些XML文件包含很多节点和方式，因此它不仅仅是一个小文件.下面的代码示例中的XML文件有50万行.

    These XML files contain a lot of nodes and ways, so it's not just a small file. The XML file in the code example below has 500K lines.

    我的代码

    class Program {
    
            static List<Way> ways = new List<Way>();
            static List<Node> nodes = new List<Node>();
    
            static void Main(String[] args) {
                read();
            }
            public static void read() {
                String xmlLoc = @"C:\Users\MyName\Desktop\result.xml";
                long time = DateTime.Now.Ticks;
                Parse(xmlLoc);
                long time2 = DateTime.Now.Ticks;
                Console.WriteLine("Done: {0} ms", (time2 - time) / 10000);
                Console.WriteLine(" - Nodes Amount:" + nodes.Count());
                Console.WriteLine(" - Ways Amount: " + ways.Count());
            }
    
            private static Node GetByRef(long reference) {
                return nodes.First(x => x.ID == reference);
            }
    
            private static void Parse(string path) {
                using (XmlReader reader = XmlReader.Create(path)) {
                    reader.MoveToContent();
                    while (reader.Read()) {
                        if (reader.NodeType == XmlNodeType.Element) {
                            XElement element = XElement.ReadFrom(reader) as XElement;
                            if ( element.Name.ToString().Equals("w")) {
                                Way w = new Way();
                                var name = element.Attribute("nm");
                                if (name != null) w.Name = name.Value;
                                var children = element.Descendants("nd");
                                foreach (XElement child in children) w.References.Add(long.Parse(child.Attribute("rf").Value));
                                ways.Add(w);
                            }else if (element.Name.ToString().Equals("n")) {
                                Node n = new Node();
                                n.ID = long.Parse(element.Attribute("id").Value);
                                n.Lon = double.Parse(element.Attribute("l").Value);
                                n.Lat = double.Parse(element.Attribute("b").Value);
                                nodes.Add(n);
                            }
                        }
                    }
                }
            }
        }
    
        class Way {
    
            public List<long> References { get; private set; }
            public long ID { get; set; }
            public String Name { get; set; }
            public bool OneWay { get; set; }
    
            public Way() {
                this.References = new List<long>();
            }
        }
    
        class Node {
            public long ID { get; set; }
            public double Lat { get; set; }
            public double Lon { get; set; }
        }
    

    当前，类Way和Node之间没有实际关系.只有一个具有long值的列表.我不知何故需要在Way类中添加一个带有Nodes的列表，但这将需要我处理另一个(两个?)for/while循环.我相信那将意味着O(N4)，这很慢.

    Currently there's no actual relation between the class Way and the class Node. There's only a list with long values. I somehow need to add a list with Nodes to the class Way, but that'll require me to work with another (two?) for/while loops. That would mean O(N4) I believe, which is slow.

    从技术上讲，我正在寻找一种解决方案和更好地构建此解决方案的方法，如果您有建议，我想听听它！

    Technically I am looking for both a solution and ways to build this better, if you have advise I'd like to hear it!

    提前谢谢！

    PS::如果我应该更新/编辑问题，请告诉我，而不是立即投票.

    PS: If I should update/edit my question, please tell me instead of downvoting immediately.

    推荐答案

    使用xml linq

    Use xml linq

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Data;
    using System.Xml;
    using System.Xml.Linq;
    using System.IO;
    
    
    namespace ConsoleApplication31
    {
        class Program
        {
            const string FILENAME = @"c:\temp\test.xml";
            static void Main(string[] args)
            {
    
                XDocument xdoc = XDocument.Load(FILENAME);
    
                var results = xdoc.Elements("root").Select(x => new
                {
                    ns = x.Descendants("n").Select(y => new {
                        id = (long)y.Attribute("id"),
                        l = (double)y.Attribute("l"),
                        b = (double)y.Attribute("b")
                    }).ToList(),
                    ws = x.Descendants("w").Select(y => new {
                        id = (long)y.Attribute("id"),
                        rfs= y.Descendants("nd").Select(z => (long)z.Attribute("rf")).ToList()
                    }).ToList()
                }).FirstOrDefault();
    
            }
        }
    
    }
    

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