D3.js中的线段

时间:2016-03-13 20:09:31

标签: d3.js svg

我创建了一条连接D3中各种数据点的线,作为音乐可视化项目的一部分:

d3.svg.line() generator with step-after interpolation

但是,我需要以不同的方式为各种线段着色。我这样做是通过创建多行而不是使用line()生成器(即每个段一行),但是我以这种方式丢失了最想要的插值:

line per segment; without interpolation

注意:笔划颜色不仅在开头也会在行的其他部分不同。

所以,我想问一下,是否有办法将两种特征结合起来(不同的颜色笔划和后续插值)。这是我的代码的主要部分(d3.svg.line()示例),作为提示:

<script>
var margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = 1200 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.scale.linear()
    .range([0, width]);

var y = d3.scale.linear()
    .range([height, 100]);

var tickValuesArray = [0];
for (var i = 1; i < 27; i++) {
  var newTick = i*16+1;
  tickValuesArray.push(newTick);
}    

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .tickValues(tickValuesArray)
    .tickFormat(function(d,i) {return i+1 })
    .innerTickSize(-height)
    .tickPadding(10);

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("left")
    .ticks(22)
    .tickFormat(function(d) {
      if (d == 0) {return "A"}
      else if (d == 1) {return "B-"}
      else if (d == 2) {return "B"}
      else if (d == 3) {return "c"}
      else if (d == 4) {return "c#"}
      else if (d == 5) {return "d"}
      else if (d == 6) {return "d#"}
      else if (d == 7) {return "e"}
      else if (d == 8) {return "f"}
      else if (d == 9) {return "f#"}
      else if (d == 10) {return "g"}
      else if (d == 11) {return "g#"}
      else if (d == 12) {return "a"}
      else if (d == 13) {return "b-"}
      else if (d == 14) {return "b"}
      else if (d == 15) {return "cc"}
      else if (d == 16) {return "cc#"}
      else if (d == 17) {return "dd"}
      else if (d == 18) {return "dd#"}
      else if (d == 19) {return "ee"}
      else if (d == 20) {return "ff"}
      else if (d == 21) {return "ff#"}
      else {return "gg"}; 
    })
    .innerTickSize(-width)
    .tickPadding(10);

var line = d3.svg.line()
    .interpolate("step-after")
    .defined(function(d) { return !isNaN(d.pitch); })
    .x(function(d) {
      return x(d.times);
    })
    .y(function(d) {
      return y(d.pitch);
    });

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");   


d3.tsv("linearAcomplete.tsv", type, function(error, data) {
  if (error) throw error;

  x.domain(d3.extent(data, function(d) { return d.times; }));
  y.domain(d3.extent(data, function(d) { return d.pitch; }));

  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

  svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Pitch");

  svg.append("path")
      .datum(data) 
      .attr("class", "line")
      .attr("d", line)
      .attr("stroke", "green"); // can I be more "flexible" here?

});

function type(d) {
  d.times = +d.times;
  d.pitch = +d.pitch;
  d.duration = +d.duration;
  return d;
}
</script>

感谢您提供的任何建议! 干杯 - 伊利亚斯

1 个答案:

答案 0 :(得分:1)

您可以使用线性渐变来执行此操作,但它需要您以百分比计算颜色的开始/停止点。这是一个简单的例子:

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
  .line {
    fill: none;
  }
  
  .axis {
    font: 10px sans-serif;
  }
  
  .axis path,
  .axis line {
    fill: none;
    stroke: #000;
    shape-rendering: crispEdges;
  }
</style>

<body>
  <script src="//d3js.org/d3.v3.min.js"></script>
  <script>
    var margin = {
        top: 20,
        right: 20,
        bottom: 30,
        left: 40
      },
      width = 960 - margin.left - margin.right,
      height = 500 - margin.top - margin.bottom;

    var x = d3.scale.linear()
      .range([0, width]);

    var y = d3.scale.linear()
      .range([height, 0]);

    var xAxis = d3.svg.axis()
      .scale(x)
      .orient("bottom");

    var yAxis = d3.svg.axis()
      .scale(y)
      .orient("left");

    var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
      .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

    var grad = svg.append('defs')
      .append('linearGradient')
      .attr('id', 'grad');

    grad.append('stop')
      .attr('stop-color', 'green');

    grad.append('stop')
      .attr('stop-color', 'green')
      .attr('offset', '25%');

    grad.append('stop')
      .attr('stop-color', 'red')
      .attr('offset', '25%');

    grad.append('stop')
      .attr('stop-color', 'red')
      .attr('offset', '50%');

    grad.append('stop')
      .attr('stop-color', 'green')
      .attr('offset', '50%');

    grad.append('stop')
      .attr('stop-color', 'green')
      .attr('offset', '100%');


    var data = d3.range(100).map(function(d) {
      return {
        x: d,
        y: Math.random() * 10
      };
    })

    var line = d3.svg.line()
      .interpolate("step-after")
      .x(function(d) {
        return x(d.x);
      })
      .y(function(d) {
        return y(d.y);
      });

    x.domain([0, 100]);
    y.domain([0, d3.max(data, function(d) {
      return d.y;
    }) * 1.1]);

    svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

    svg.append("g")
      .attr("class", "y axis")
      .call(yAxis);

    svg.append("path")
      .datum(data)
      .attr("class", "line")
      .attr("d", line)
      .attr("stroke", "url(#grad)");
  </script>
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