D3折线/面积图是否可以处理无序数据? [英] Can a D3 line/area chart work on unordered data?

问题描述

请参考以下链接: https://bl.ocks.org/mbostock/34f08d5e11952a80609169b7917d4172

在这里数据是有序的(按顺序排列)，如jan 2000，feb 2000等，但我想使此d3图在无序数据(如jan 2001，feb 2000等)上起作用.有可能吗?

Here the data is ordered (in sequence) like jan 2000, feb 2000 etc but i want to make this d3 graph work on unordered data like jan 2001 ,feb 2000 etc. Is it possible ?

推荐答案

简短回答:否.

行生成器或区域生成器(即块中的那个)将根据输入数据的顺序生成一条线(或一个区域).该API明确指出了这一点:

The line generator or the area generator (which is the one in that blocks) will generate a line (or an area) based on the input data in its order. The API makes it clear:

d3.line():为给定的数据数组生成一行.根据此线生成器的相关曲线，在将给定的输入数据传递给线生成器之前，可能需要按x值进行排序. (强调我的)

d3.line(): Generates a line for the given array of data. Depending on this line generator’s associated curve, the given input data may need to be sorted by x-value before being passed to the line generator. (emphasis mine)

让我们在一个基本示例中看到这一点.我有一组值和年份，其中的年份未排序:

Let's see this in a basic example. I have an array of values and years, in which the years are not sorted:

var data = [{
  year: 2010,
  value: 100
}, {
  year: 2017,
  value: 70
}, {
  year: 2012,
  value: 50
}, {
  year: 2016,
  value: 10
}, {
  year: 2013,
  value: 90
}, {
  year: 2014,
  value: 20
}, {
  year: 2011,
  value: 50
}, {
  year: 2015,
  value: 40
}];

如果我将数据按现在的方式传递给线生成器，则这是折线图:

This is the line chart we have if I pass the data to the line generator the way it is right now:

var svg = d3.select("svg");
var data = [{
  year: 2010,
  value: 100
}, {
  year: 2017,
  value: 70
}, {
  year: 2012,
  value: 50
}, {
  year: 2016,
  value: 10
}, {
  year: 2013,
  value: 90
}, {
  year: 2014,
  value: 20
}, {
  year: 2011,
  value: 50
}, {
  year: 2015,
  value: 40
}];

var parseTime = d3.timeParse("%Y");

data.forEach(function(d) {
  d.year = parseTime(d.year)
});

var xScale = d3.scaleTime()
  .domain(d3.extent(data, function(d) {
    return d.year
  }))
  .range([0, 300]);

var yScale = d3.scaleLinear()
  .domain(d3.extent(data, function(d) {
    return d.value
  }))
  .range([150, 0]);

var lineGenerator = d3.line()
  .x(function(d) {
    return xScale(d.year)
  })
  .y(function(d) {
    return yScale(d.value)
  })
  .curve(d3.curveMonotoneX)

svg.append("path")
  .style("fill", "none")
  .style("stroke", "teal")
  .style("stroke-width", "2px")
  .attr("d", lineGenerator(data));

<script src="https://d3js.org/d3.v4.min.js"></script>
<svg></svg>

现在使用相同的代码，但是对数据进行排序:

Now the same code, but sorting the data:

data.sort(function(a, b) {
    return d3.ascending(a.year, b.year)
});

这是结果:

var svg = d3.select("svg");
var data = [{
  year: 2010,
  value: 100
}, {
  year: 2017,
  value: 70
}, {
  year: 2012,
  value: 50
}, {
  year: 2011,
  value: 10
}, {
  year: 2013,
  value: 90
}, {
  year: 2014,
  value: 20
}, {
  year: 2016,
  value: 50
}, {
  year: 2015,
  value: 40
}];

var parseTime = d3.timeParse("%Y");

data.forEach(function(d) {
  d.year = parseTime(d.year)
});

data.sort(function(a, b) {
  return d3.ascending(a.year, b.year)
})

var xScale = d3.scaleTime()
  .domain(d3.extent(data, function(d) {
    return d.year
  }))
  .range([0, 300]);

var yScale = d3.scaleLinear()
  .domain(d3.extent(data, function(d) {
    return d.value
  }))
  .range([150, 0]);

var lineGenerator = d3.line()
  .x(function(d) {
    return xScale(d.year)
  })
  .y(function(d) {
    return yScale(d.value)
  })
  .curve(d3.curveMonotoneX)

svg.append("path")
  .style("fill", "none")
  .style("stroke", "teal")
  .style("stroke-width", "2px")
  .attr("d", lineGenerator(data));

<script src="https://d3js.org/d3.v4.min.js"></script>
<svg></svg>

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