D3.js 外部 data.json 文件和画笔的范围问题

Question

使用外部文件时遇到问题 data.json 用画笔在条形图上使用。这似乎是一个范围问题。

我正在使用，

 d3.json("data.json", function(error, data) {...});

读入 json 文件。这里面绘制了主图和画笔图。并且有一个对变量 'brush' 的调用，它在 d3.json() 之外，在那个 var 中有一个对刷函数的调用，它也在 d3.json() 之外。 'data' 无法在画笔函数中读取。我尝试将数据作为参数传递，brush(data) 但这不起作用。

我得到的错误是，

Uncaught ReferenceError: data is not defined

这个错误是指刷函数中的第226行，看起来像这样，

 .data(data.filter(function(d) {....

并且是第一次使用'data'刷机功能

这与 Bostock 的示例设置相同 Brush & Zoom

<!DOCTYPE html>
<meta charset="utf-8">

<style type="text/css">
  body {
    font-family: avenir next, sans-serif;
    font-size: 12px;
  }

  .zoom {
    cursor: move;
    fill: none;
    pointer-events: all;
  }

  .axis {
    stroke-width: 0.5px;
    stroke: #888;
    font: 10px avenir next, sans-serif;
  }

  .axis>path {
    stroke: #888;
  }
</style>

<body>
</body>

<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
  var margin = {
      top: 20,
      right: 20,
      bottom: 90,
      left: 50
    },
    margin2 = {
      top: 230,
      right: 20,
      bottom: 30,
      left: 50
    },
    width = 960 - margin.left - margin.right,
    height = 300 - margin.top - margin.bottom,
    height2 = 300 - margin2.top - margin2.bottom;

  var x = d3.scaleBand().range([0, width]).padding(0.1),
    x2 = d3.scaleBand().range([0, width]).padding(0.1),
    y = d3.scaleLinear().range([height, 0]),
    y2 = d3.scaleLinear().range([height2, 0]);

  var xAxis = d3.axisBottom(x).tickSize(0),
    xAxis2 = d3.axisBottom(x2).tickSize(0),
    yAxis = d3.axisLeft(y).tickSize(0);

  var brush = d3.brushX()
    .extent([
      [0, 0],
      [width, height2]
    ])
    // .on("start brush end", brushed);
    .on("brush", brushed);

  var zoom = d3.zoom()
    .scaleExtent([1, 2])
    .translateExtent([
      [0, 0],
      [width, height]
    ])
    .extent([
      [0, 0],
      [width, height]
    ])
    .on("zoom", zoomed);

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

  svg.append("defs").append("clipPath")
    .attr("id", "clip")
    .append("rect")
    .attr("width", width)
    .attr("height", height);

  var focus = svg.append("g")
    .attr("class", "focus")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

  var context = svg.append("g")
    .attr("class", "context")
    .attr("transform", "translate(" + margin2.left + "," + margin2.top + ")");

  focus.append("text") // yAxis label
    .attr("transform", "rotate(-90)")
    .attr("y", 0 - margin.left)
    .attr("x", 0 - (height / 2))
    .attr("dy", "1em")
    .style("text-anchor", "middle")
    .text("Distance in meters");

  svg.append("text") // xAxis label
    .attr("transform",
      "translate(" + ((width + margin.right + margin.left) / 2) + " ," +
      (height + margin.top + margin.bottom) + ")")
    .style("text-anchor", "middle")
    .text("Date");

  svg.append("rect")
    .attr("class", "zoom")
    .attr("width", width)
    .attr("height", height)
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
    .call(zoom); //see var zoom above

  focus.append("g") //append xAxis to main chart
    .attr("class", "axis x-axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

  d3.json("data.json", function(error, data) {
    if (error) throw error;

    focus.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisLeft(d3.scaleLinear()
        .domain([0, d3.max(data, function(d) {
          return d.distance;
        })])
        .range([height, 0])).tickSize(0));

    data.forEach(function(d) {
        d.distance = +d.distance;
        return d;
      },
      function(error, data) {
        if (error) throw error;
      });

    x.domain(data.map(function(d) {
      return d.date;
    }));
    y.domain([0, d3.max(data, function(d) {
      return d.distance;
    })]);
    x2.domain(x.domain());
    y2.domain(y.domain());

    //********* Main ar Chart ****************

    var rects = focus.append("g");
    rects.attr("clip-path", "url(#clip)");
    rects.selectAll("rects")
      .data(data)
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rects")
      .attr("x", function(d) {
        return x(d.date);
      })
      .attr("y", function(d) {
        return y(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height - y(d.distance);
      });

    // //********* Brush Bar Chart ****************

    var rects = context.append("g"); //draw bar chart in brush
    rects.attr("clip-path", "url(#clip)");
    rects.selectAll("rect")
      .data(data)
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rectss")
      .attr("x", function(d) {
        return x2(d.date);
      })
      .attr("y", function(d) {
        return y2(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height2 - y2(d.distance);
      });

    context.append("g")
      .attr("class", "axis x-axis")
      .attr("transform", "translate(0," + height2 + ")")
      .call(xAxis2);

    context.append("g")
      .attr("class", "brush")
      .call(brush)
      .call(brush.move, x.range());

  }); //closes d3.json()

  function brushed() {
    if (d3.event.sourceEvent && d3.event.sourceEvent.type === "zoom") return; // ignore brush-by-zoom

    // get bounds of selection
    var s = d3.event.selection,
      nD = [];
    x2.domain().forEach((d) => { //not as smooth as I'd like it
      var pos = x2(d) + x2.bandwidth() / 2;
      if (pos > s[0] && pos < s[1]) {
        nD.push(d);
      }
    });

    x.domain(nD);

    focus.selectAll(".rects")
      .remove().exit()
      .data(data.filter(function(d) {
        return nD.indexOf(d.date) > -1
      }))
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rects")
      .attr("x", function(d) {
        return x(d.date);
      })
      .attr("y", function(d) {
        return y(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height - y(d.distance);
      });

    focus.select(".x-axis").call(xAxis);

    svg.select(".zoom").call(zoom.transform, d3.zoomIdentity
      .scale(width / (s[1] - s[0]))
      .translate(-s[0], 0));
  };

  function zoomed() {};
</script>

一小部分data.json

[{
    "date": "A",
    "distance": "1100"
  },
  {
    "date": "B",
    "distance": "1500"
  },

  {
    "date": "C",
    "distance": "2000"
  },
  {
    "date": "D",
    "distance": "2500"
  },
  {
    "date": "E",
    "distance": "1975"
  },
  {
    "date": "F",
    "distance": "3000"
  },
  {
    "date": "G",
    "distance": "2100"
  },
  {
    "date": "H",
    "distance": "2100"
  },
  {
    "date": "I",
    "distance": "3300"
  },
  {
    "date": "J",
    "distance": "2000"
  }
]

如有任何帮助，我们将不胜感激。

谢谢，

附录：

为什么这不起作用？

  var data = null;

  d3.json("data.json", function(error, data) {
    if (error) throw error;

.....

)}

这确实有效，

     var data = null;

      d3.json("data.json", function(error, newdata) {
        if (error) throw error;

        data = newdata;
.....});

Answer 1

您的范围确实有问题。变量数据是在一个函数内部定义的，所以它不能在这个函数之外使用。这是使其工作的代码：

    <!DOCTYPE html>
<meta charset="utf-8">

<style type="text/css">
  body {
    font-family: avenir next, sans-serif;
    font-size: 12px;
  }

  .zoom {
    cursor: move;
    fill: none;
    pointer-events: all;
  }

  .axis {
    stroke-width: 0.5px;
    stroke: #888;
    font: 10px avenir next, sans-serif;
  }

  .axis>path {
    stroke: #888;
  }
</style>

<body>
</body>

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

  var margin = {
      top: 20,
      right: 20,
      bottom: 90,
      left: 50
    },
    margin2 = {
      top: 230,
      right: 20,
      bottom: 30,
      left: 50
    },
    width = 960 - margin.left - margin.right,
    height = 300 - margin.top - margin.bottom,
    height2 = 300 - margin2.top - margin2.bottom;

  var x = d3.scaleBand().range([0, width]).padding(0.1),
    x2 = d3.scaleBand().range([0, width]).padding(0.1),
    y = d3.scaleLinear().range([height, 0]),
    y2 = d3.scaleLinear().range([height2, 0]);

  var xAxis = d3.axisBottom(x).tickSize(0),
    xAxis2 = d3.axisBottom(x2).tickSize(0),
    yAxis = d3.axisLeft(y).tickSize(0);

  var brush = d3.brushX()
    .extent([
      [0, 0],
      [width, height2]
    ])
    // .on("start brush end", brushed);
    .on("brush", brushed);

  var zoom = d3.zoom()
    .scaleExtent([1, 2])
    .translateExtent([
      [0, 0],
      [width, height]
    ])
    .extent([
      [0, 0],
      [width, height]
    ])
    .on("zoom", zoomed);

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

  svg.append("defs").append("clipPath")
    .attr("id", "clip")
    .append("rect")
    .attr("width", width)
    .attr("height", height);

  var focus = svg.append("g")
    .attr("class", "focus")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

  var context = svg.append("g")
    .attr("class", "context")
    .attr("transform", "translate(" + margin2.left + "," + margin2.top + ")");

  focus.append("text") // yAxis label
    .attr("transform", "rotate(-90)")
    .attr("y", 0 - margin.left)
    .attr("x", 0 - (height / 2))
    .attr("dy", "1em")
    .style("text-anchor", "middle")
    .text("Distance in meters");

  svg.append("text") // xAxis label
    .attr("transform",
      "translate(" + ((width + margin.right + margin.left) / 2) + " ," +
      (height + margin.top + margin.bottom) + ")")
    .style("text-anchor", "middle")
    .text("Date");

  svg.append("rect")
    .attr("class", "zoom")
    .attr("width", width)
    .attr("height", height)
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
    .call(zoom); //see var zoom above

  focus.append("g") //append xAxis to main chart
    .attr("class", "axis x-axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

  var data_global=null;

  d3.json("data.json", function(error, data) {
    if (error) throw error;

    data_global=data;
    focus.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisLeft(d3.scaleLinear()
        .domain([0, d3.max(data, function(d) {
          return d.distance;
        })])
        .range([height, 0])).tickSize(0));

    data.forEach(function(d) {
        d.distance = +d.distance;
        return d;
      },
      function(error, data) {
        if (error) throw error;
      });

    x.domain(data.map(function(d) {
      return d.date;
    }));
    y.domain([0, d3.max(data, function(d) {
      return d.distance;
    })]);
    x2.domain(x.domain());
    y2.domain(y.domain());

    //********* Main ar Chart ****************

    var rects = focus.append("g");
    rects.attr("clip-path", "url(#clip)");
    rects.selectAll("rects")
      .data(data)
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rects")
      .attr("x", function(d) {
        return x(d.date);
      })
      .attr("y", function(d) {
        return y(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height - y(d.distance);
      });

    // //********* Brush Bar Chart ****************

    var rects = context.append("g"); //draw bar chart in brush
    rects.attr("clip-path", "url(#clip)");
    rects.selectAll("rect")
      .data(data)
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rectss")
      .attr("x", function(d) {
        return x2(d.date);
      })
      .attr("y", function(d) {
        return y2(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height2 - y2(d.distance);
      });

    context.append("g")
      .attr("class", "axis x-axis")
      .attr("transform", "translate(0," + height2 + ")")
      .call(xAxis2);

    context.append("g")
      .attr("class", "brush")
      .call(brush)
      .call(brush.move, x.range());

  }); //closes d3.json()

  function brushed() {
    if (d3.event.sourceEvent && d3.event.sourceEvent.type === "zoom") return; // ignore brush-by-zoom

    // get bounds of selection
    var s = d3.event.selection,
      nD = [];
    x2.domain().forEach((d) => { //not as smooth as I'd like it
      var pos = x2(d) + x2.bandwidth() / 2;
      if (pos > s[0] && pos < s[1]) {
        nD.push(d);
      }
    });

    x.domain(nD);

    focus.selectAll(".rects")
      .remove().exit()
      .data(data_global.filter(function(d) {
        return nD.indexOf(d.date) > -1
      }))
      .enter().append("rect")
      .style("fill", function(d) {
        return "lightblue";
      })
      .style('stroke', 'gray')
      .attr("class", "rects")
      .attr("x", function(d) {
        return x(d.date);
      })
      .attr("y", function(d) {
        return y(d.distance);
      })
      .attr("width", x.bandwidth())
      .attr("height", function(d) {
        return height - y(d.distance);
      });

    focus.select(".x-axis").call(xAxis);

    svg.select(".zoom").call(zoom.transform, d3.zoomIdentity
      .scale(width / (s[1] - s[0]))
      .translate(-s[0], 0));
  };

  function zoomed() {};
</script>

D3.js 外部 data.json 文件和画笔的范围问题

D3.js scope issue with external data.json file and brush

scope

external

d3.js