使用 Node js 和 D3 实时在地图上绘制状态名称 [英] Plotting Name of States on Map using Node js and D3 in real time

问题描述

我一直在尝试使用 Redis Pub/Sub 系统、Node js 和 D3 在地图上绘制州的名称.问题是当我第一次在 Redis 频道上输入一个状态时，它被完美地绘制，但是当我输入第二个状态时，什么也没有发生.由于我是 D3.js 的新手，因此无法弄清楚问题所在.任何帮助将不胜感激.谢谢.

I have been trying to plot the names of the states on the map using Redis Pub/Sub system, Node js and D3. Issue is that when I type in a state for first time on a Redis channel, it is plotted perfectly, but when I type in the second state, nothing happens. Since I am new to D3.js, am not able to figure out the problem. Any help will be appreciated. Thanks.

d3.json("india-states.json", function (json) {
    india.selectAll("path")
    .data(json.features)
    .enter().append("path")
    .attr("d", path);
    var socket = io();
    socket.on('tags', function(data){
        console.log(data.message1);
        india.selectAll("text")
        .data(json.features)
        .enter()
        .append("text")
        .attr("fill", "black")
        .attr("transform", function(d) {
            console.log(data.message1 + "Second Time"); 
            var centroid = path.centroid(d);
            return "translate(" + centroid[0] + "," + centroid[1] + ")"
        })
        .attr("text-anchor", "middle")
        .attr("dy", ".35em")
        .style('fill', 'white')
        .text(function(d) {
            console.log("2");
            if (d.id == data.message1) {
                console.log("1");    
                return data.message1;
            }
        });
    });
});

我尝试探索我的代码，发现它每次都能正确获取状态名称.但只有在第一次尝试时，状态名称才会在

I tried exploring my code and found that it is correctly fetching the state name every time. But only in first attempt the state name goes forward after

console.log(data.message1);

在所有其他情况下，我只得到一个控制台输出，那就是console.log(data.message1);"

In all other cases I get only one console output and that is the "console.log(data.message1);"

推荐答案

为文本创建一个变量并将其移到socket之外:

Create a variable for the texts and move it outside socket:

d3.json("india-states.json", function (json) {
india.selectAll("path")
  .data(json.features)
  .enter().append("path")
  .attr("d", path);

var stateText = india.selectAll(".text")
  .data(json.features)
  .enter()
  .append("text");//variable outside socket

var socket = io();

socket.on('tags', function(data){

    stateText.attr("fill", "black")
      .attr("transform", function(d) {
        console.log(data.message1 + "Second Time"); 
        var centroid = path.centroid(d);
        return "translate(" + centroid[0] + "," + centroid[1] + ")"
      })
      .attr("text-anchor", "middle")
      .attr("dy", ".35em")
      .style('fill', 'white')
      .text(function(d) {
        if (d.id == data.message1) {   
            return data.message1;
          }
      });
  });
});

如果你想跟踪你之前的message1，你可以在函数外创建一个数组，并循环遍历它:

If you want to keep track of your previous message1, you can create an array outside the function, and loop through it:

d3.json("india-states.json", function (json) {
india.selectAll("path")
  .data(json.features)
  .enter().append("path")
  .attr("d", path);

var stateText = india.selectAll(".text")
  .data(json.features)
  .enter()
  .append("text");

var arrayStates = [];//this array will hold all the names

var socket = io();

socket.on('tags', function(data){

    arrayStates.push(data.message1);//for each input, a new string

    stateText.attr("fill", "black")
    .attr("transform", function(d) {
        var centroid = path.centroid(d);
        return "translate(" + centroid[0] + "," + centroid[1] + ")"
    })
    .attr("text-anchor", "middle")
    .attr("dy", ".35em")
    .style('fill', 'white')
    .text(function(d) {
        for(var i = 0; i < arrayStates.length; i++){
          if (d.id == arrayStates[i]) {   
            return arrayStates[i];
          }
        }
     });
  });
});

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