找不到D3js强制定向图链接 [英] D3js Force Directed Graph Link not found

问题描述

我目前正在尝试使用d3js v4构建强制图.我有以下节点和链接，实际上很简单

I'm currently trying to build a force directed graph with d3js v4. I have the following nodes and links, actually pretty simple

节点

[
  {
    "id":"4d2b0275-5bc7-e611-81c4-00155df7ea33"
  },{
    "id":"b32b0275-5bc7-e611-81c4-00155df7ea33"
  }
]

链接

[
  {
    "source":"4d2b0275-5bc7-e611-81c4-00155df7ea33",
    "target":"b32b0275-5bc7-e611-81c4-00155df7ea33"
  }
]

我的forceSimulation设置是

my forceSimulation setup is

var simulation = d3.forceSimulation(nodes)
    .force("charge", d3.forceManyBody())
    .force("link", d3.forceLink(links).distance(20).strength(1))
    .force("x", d3.forceX())
    .force("y", d3.forceY())
    .stop()

它在带有Uncaught Error: missing: 4d2b0275-5bc7-e611-81c4-00155df7ea33的d3.forceLink(links)上引发错误. 那么既然链接实际上在那儿，为什么会出错呢?

It throws an error on d3.forceLink(links) with Uncaught Error: missing: 4d2b0275-5bc7-e611-81c4-00155df7ea33. so why is that error since the link is actually there?

推荐答案

在D3中，默认

In D3, the default link.id() accessor function:

允许将每个链接的源和目标指定为节点数组中从零开始的索引.

allows each link’s source and target to be specified as a zero-based index into the nodes array.

这意味着源和目标由节点的索引定义，如本示例中的API:

This means that the source and the target are defined by the index of the node, as in this example in the API:

var links = [
    {"source": 0, "target": 1}, //from the first node to the second
    {"source": 1, "target": 2} //from the second node to the third
];

但是，由于要通过节点的id而不是其数字索引来定义源和目标，因此必须在id()函数中指定此ID:

However, since you're defining the source and the target by the id of the node, not by its numeric index, you have to specify this id in the id() function:

.force("link", d3.forceLink(links)
     .id(function(d,i) {
         return d.id
     })
    .distance(20)
    .strength(1)
)

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