D3饼图的数据结构 [英] Data structure for D3 pie charts

问题描述

我目前正在进行D3数据可视化的第一步。到目前为止，D3教程已经帮助了我很多。饼图教程 http://bl.ocks.org/mbostock/3887235 虽然不进一步解释饼图的必要数据结构。

I am currently taking my first steps in D3 data visualisation. So far, the D3 tutorials have helped me a lot. The pie chart tutorial http://bl.ocks.org/mbostock/3887235 though does not further explain the necessary data structure for pie charts.

我的数据比示例的标签/值结构更复杂。我有年度总导入数据和导入数据的特定商品存储在JSON：

My data is more complex than the label/value structure of the example. I have the annual total import data and import data of a specific good stored in JSON:

var data = [{"year":"2001","total_import":"100000","import_specific_good":"25000"},{"year":"2002",...}];

如果我理解教程正确pie（）迭代每个DIFFERENT对象的SAME条目。

If I understand the tutorial correctly pie() iterates over the SAME entry of each DIFFERENT object.

如果我需要SAME物件的特定DIFFERENT值，该怎么办？

What if I need specific DIFFERENT values of the SAME object?

所有年度总进口作为部分，而每年进口特定商品作为年度总进口的一部分。我的值将是1.（total_import - import_specific_good）和2. import_specific_good。

I am not interested in a pie showing all annual total imports as portions, but the annual import of a specific good as a portion of the annual total import. My values would be 1. (total_import - import_specific_good) and 2. import_specific_good.

我建议的数据结构是否正确，我想做什么？

Is my proposed data structure correct for what I want to do? Or do I have to restructure everything so that the values for every year are stored in a separate variable?

var data_2001 = [{"label":"Total Import","value":"100000"},{"label":"Import of Specific Good","value":"25000"}];

var data_2002 = [{"label": ...}];

推荐答案

您不必使用特定的数据结构 - 你可以（并将需要反正）修改示例，所以你可以使用任何你喜欢的！所以你可以使用你的第一个JSON就好了。因为你只有两个值可以显示，你可以简单的构造结构传递到 .data（）即时。

You don't have to use a specific data structure -- you can (and will need to anyway) modify the example so you can use anything you like! So you can use your first JSON just fine. As you have only 2 values to show, you could simply construct the structure to pass to .data() on the fly.

// for pie chart
...data([json[index].total_import - json[index].import_specific_good,
         json[index].import_specific_good])...
...
// similarly for the labels

我建议您在JSON中将数字存储为数字（例如，不使用引号），否则您必须将它们转换为Javascript中的数字。

I would advise to store the numbers as numbers (e.g. without quotes) in your JSON though -- otherwise you'll have to convert them to numbers in Javascript.

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