具有from to值的D3切片数组

Question

我有一个类似下面的数据集，

const data = [
    {frequency: 600, letter: 0, luminous: 234},
    {frequency: 2456, letter: 13, luminous: 4000},
    {frequency: 1200, letter: 2, luminous: 1402},
    {frequency: 1400, letter: 3, luminous: 1500},
    {frequency: 1234, letter: 4, luminous: 1800},
    {frequency: 768, letter: 5, luminous: 1900},
    {frequency: 3456, letter: 9, luminous: 2300},
    {frequency: 4567, letter: 10, luminous: 670},
    {frequency: 600, letter: 6, luminous: 2233},
    {frequency: 350, letter: 7, luminous: 1450},
    {frequency: 2340, letter: 8, luminous: 1470},
    {frequency: 4200, letter: 11, luminous: 5600},
    {frequency: 3000, letter: 12, luminous: 4500},
    {frequency: 1200, letter: 14, luminous: 4200},
    {frequency: 1100, letter: 15, luminous: 3000},
    {frequency: 1700, letter: 16, luminous: 4500},
];

我需要使用from值和2值对此数组数据进行切片，并使用d3

const maxLetter = d3.max(data, d => d.letter);
const width = 400;
const scaleX = scaleLinear()
    .domain([0, maxLetter])
    .range([0, width])
    .clamp(true)

是否可以从开始letter = 2开始对我的data数组进行切片，以结束此范围内的所有内容作为新数组？就像下面的d3？

const newData = [
    {frequency: 1200, letter: 2, luminous: 1402},
    {frequency: 1400, letter: 3, luminous: 1500},
    {frequency: 1234, letter: 4, luminous: 1800},
    {frequency: 768, letter: 5, luminous: 1900},
    {frequency: 600, letter: 6, luminous: 2233},
    {frequency: 350, letter: 7, luminous: 1450},
    {frequency: 2340, letter: 8, luminous: 1470},
    {frequency: 3456, letter: 9, luminous: 2300}
];

Answer 1

为什么不用一个简单的循环呢？如下所示：

var newData = [];
for(var i = 0; i < data.length; i++){
  if(data[i].letter >= 2 && data[i].letter < 10){
    newData.push(data[i]);
  }
}

要获得按letter排序的newData数组，可以使用一个比较器：newData.sort((a, b) => a.letter - b.letter)

Answer 2

要对数据执行操作，是最佳解决方案。

• 根据关键字母
• 将数据馈送到data维中使用筛选出data

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const data = [
    {frequency: 600, letter: 0, luminous: 234},
    {frequency: 2456, letter: 13, luminous: 4000},
    {frequency: 1200, letter: 2, luminous: 1402},
    {frequency: 1400, letter: 3, luminous: 1500},
    {frequency: 1234, letter: 4, luminous: 1800},
    {frequency: 768, letter: 5, luminous: 1900},
    {frequency: 3456, letter: 9, luminous: 2300},
    {frequency: 4567, letter: 10, luminous: 670},
    {frequency: 600, letter: 6, luminous: 2233},
    {frequency: 350, letter: 7, luminous: 1450},
    {frequency: 2340, letter: 8, luminous: 1470},
    {frequency: 4200, letter: 11, luminous: 5600},
    {frequency: 3000, letter: 12, luminous: 4500},
    {frequency: 1200, letter: 14, luminous: 4200},
    {frequency: 1100, letter: 15, luminous: 3000},
    {frequency: 1700, letter: 16, luminous: 4500},
];

const CFX = crossfilter(data);
const dimension = CFX.dimension(function (d){ return d.letter; });

console.dir(dimension.top(Infinity).length);
dimension.filterRange([2, 10]);

console.dir(dimension.top(Infinity));
console.dir(dimension.top(Infinity).length);

<script src="http://dc-js.github.io/dc.js/js/crossfilter.js"></script>

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