Javascript D3：从 csv 到数组答案

【问题标题】：Javascript D3: from csv to arrayJavascript D3：从 csv 到数组
【发布时间】：2018-07-20 18:28:36
【问题描述】：

我从这个页面https://bl.ocks.org/mbostock/34f08d5e11952a80609169b7917d4172下载了javascript代码。我想进行更改，实际上 html 页面从 csv 文件中获取数据，而我想直接从同一 html 页面上的数组中获取数据。也就是说，我想在 index.html 中创建一个简单的数字数组和一个月份数组，并从那里获取数据。

这是获取数据的部分：

d3.csv("sp500.csv", type, function(error, data) {
  if (error) throw error;

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

  focus.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area);

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

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

  context.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area2);

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

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

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

虽然我想在 html 页面上有一个数字数组和一个数组 di 月，但不使用 csv：

var price = [9, 6, 2];
var date = [Jan 2000, Feb 2000, Mar 2000]

我该怎么办？谢谢

【问题讨论】：

标签： javascript arrays d3.js visualization data-visualization

【解决方案1】：

这是一个bl.ock，它将一个数组作为输入。

var data = [{date: 'Jan 2000', price: 9}, {date: 'Feb 2000', price:6},{date: 'Mar 2000', price: 2}];

data.forEach(function (d) {
  d.date = parseDate(d.date);
  d.price = +d.price;
});

一个相同的sn-p：

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

.area {
  fill: steelblue;
  clip-path: url(#clip);
}

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

</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    margin = {top: 20, right: 20, bottom: 110, left: 40},
    margin2 = {top: 430, right: 20, bottom: 30, left: 40},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    height2 = +svg.attr("height") - margin2.top - margin2.bottom;

var parseDate = d3.timeParse("%b %Y");

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

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

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

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

var area = d3.area()
    .curve(d3.curveMonotoneX)
    .x(function(d) { return x(d.date); })
    .y0(height)
    .y1(function(d) { return y(d.price); });

var area2 = d3.area()
    .curve(d3.curveMonotoneX)
    .x(function(d) { return x2(d.date); })
    .y0(height2)
    .y1(function(d) { return y2(d.price); });

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 + ")");

var data = [{date: 'Jan 2000', price: 9}, {date: 'Feb 2000', price:6},{date: 'Mar 2000', price: 2}];
  
data.forEach(function (d) {
  d.date = parseDate(d.date);
  d.price = +d.price;
});
  
  x.domain(d3.extent(data, function(d) { return d.date; }));
  y.domain([0, d3.max(data, function(d) { return d.price; })]);
  x2.domain(x.domain());
  y2.domain(y.domain());

  focus.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area);

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

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

  context.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area2);

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

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

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

function brushed() {
  if (d3.event.sourceEvent && d3.event.sourceEvent.type === "zoom") return; // ignore brush-by-zoom
  var s = d3.event.selection || x2.range();
  x.domain(s.map(x2.invert, x2));
  focus.select(".area").attr("d", area);
  focus.select(".axis--x").call(xAxis);
  svg.select(".zoom").call(zoom.transform, d3.zoomIdentity
      .scale(width / (s[1] - s[0]))
      .translate(-s[0], 0));
}

function zoomed() {
  if (d3.event.sourceEvent && d3.event.sourceEvent.type === "brush") return; // ignore zoom-by-brush
  var t = d3.event.transform;
  x.domain(t.rescaleX(x2).domain());
  focus.select(".area").attr("d", area);
  focus.select(".axis--x").call(xAxis);
  context.select(".brush").call(brush.move, x.range().map(t.invertX, t));
}

</script>

希望这会有所帮助。

【讨论】：

【解决方案2】：

您可以跳过csv 函数并使用您自己的数据

而不是

d3.csv("sp500.csv", type, function(error, data) {
  if (error) throw error;

  x.domain(d3.extent(data, function(d) { return d.date; }));
  //...
})

你可以这样做：

var data = [{date:'Jan 2000', price: 9}, {}, {}, ...];

x.domain(d3.extent(data, function(d) { return d.date; }));
//...

如果你想保留它的功能，你也可以：

var process = function(data) {
  x.domain(d3.extent(data, function(d) { return d.date; }));
  //...
})

process({date:'Jan 2000', price: 9}, {}, {}, ...]); // <-- the data

【讨论】：