D3 v4 - 访问选择数组并找到相应的元素 [英] D3 v4 - Accessing selection array and find corresponding element

问题描述

我试图得到一个约束放松为我的饼图工作。
它基于此示例 https://jsfiddle.net/thudfactor/HdwTH/ 但是使用的放松方法似乎不再适用于v4。

具体的问题是他们如何直接访问选择组数组：

I'm trying to get a constraint relaxing to work for my piechart. It is based on this example https://jsfiddle.net/thudfactor/HdwTH/ but the relaxing method used seems not to work with v4 any more.
The concrete problem is how they access the selection group array directly:

textLabels = labelGroups.append("text").attr( ... );

if(again) {
        labelElements = textLabels[0];     <------------- here
        textLines.attr("y2",function(d,i) {
            labelForLine = d3.select(labelElements[i]);
            return labelForLine.attr("y");
        });
        setTimeout(relax,20)
    }

.x如何访问选择组数组？

现在怎么办？

Has it changed with D3 v4.x how you access a selections group array?
How would you go about it now?

推荐答案

在D3 4.0中，选择不再是数组。根据API：

In D3 4.0, selections are not arrays anymore. According to the API:

选择不再使用原型链注入的子类Array;它们现在是平面对象，提高性能。

Selections no longer subclass Array using prototype chain injection; they are now plain objects, improving performance.

因此，如果您 console.log（textLabels）看到这样的东西：

So, if you console.log(textLabels), you're gonna see something like this:

{_groups: Array[1], _parents: Array[1]}

根据您所选择的内容。从这里，你可以使用 textLabels._groups 访问你的数组。

Depending on exactly what are you selecting. From there, you can access your array using textLabels._groups, for instance.

必须使用 selection.nodes（），根据API：

For having an array, you have to use selection.nodes(), which, according to the API:

返回此选择中所有（非空）元素的数组。

Returns an array of all (non-null) elements in this selection.

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