enthal · November 14, 2020 02:55
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <title>series normalization per mouse-x (in d3.js)</title>
 <style>
 svg .chart {
  fill: none;
  stroke: #000;
  stroke-width: 2px;
 }
 svg rect.mouse {
  fill: none;
  pointer-events: all;
 }

 svg .guides {
  stroke-width: 1px;
 }
 svg .guides line {
  stroke: #BBC;
  shape-rendering: crispEdges;
 }
 svg .guides circle {
  fill: #BBC;
  stroke: #348;
  opacity: 0.3;
 }
 </style>

 <body></body>

 <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js" charset="utf-8"></script>
 <script>

 var n=100, seriesList = [];
 pushSeries(function(i) { return Math.sin(i*Math.PI/(n*0.2))+2; });
 pushSeries(function(i) { return Math.cos(i*Math.PI/(n*0.3))+2; });
 pushSeries(function(i) { return Math.cos(i*Math.PI/(n*0.15))/2+3*i/n+2; });
 pushSeries(function(i) { return Math.pow(i/n,1.8)+1; });

 var width = 960,
    height = 500;

 var x = d3.scale.linear().range([0, width]);
 var y = d3.scale.linear().range([height, 0]);
 var series = seriesList[0];
 x.domain([0, n]);

 var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height);
 var chart = svg.append('g').classed('chart', true);

 var guides;
 effectScaledPaths(0);

 guides = chart.append("svg:g")
  .classed("guides", true);
 guides.append("svg:line")
  .attr("y1",height);
 var yGuides = guides.append("svg:g")
 yGuides.append("svg:circle")
  .attr("r",7);
 yGuides.append("svg:line")
  .attr("x1",-20)
  .attr("x2",+20);



 svg.append("rect").classed("mouse", true)
  .attr("width", width)
  .attr("height", height)
  .on("mousemove", mousemove)
  .on("mouseout",  mouseout);

 mouseout();



 function pushSeries(fn) {
  var s = [];
  seriesList.push(s);
  for (var i=0;i<n;i++) { s.push(fn(i)); }
 }

 function mousemove() {
  effectScaledPaths(Math.floor(x.invert(d3.mouse(this)[0])));  // TODO: bisect when x domain isn't index?
 }
 function mouseout() {
  // guides.attr("visibility", "hidden");
 }

 var lastX0 = 0;
 function effectScaledPaths(x0) {
  /*
  Scale each series to be proportional to its value at x0,
  such that all series cross at some single point at mouse.x,
  setting y.domain to extent of extents of all so-scaled series (i.e., global max,min).
  */

  if (x0 === lastX0) { return; }
  lastX0 = x0;

  var ss = seriesList.slice();
  var extents = [];
  for (var ssi in ss) {
    var s = ss[ssi] = ss[ssi].slice();
    var factor = 1.0 / s[x0];    // but nothing is proportional to a value of 0
    for (var si in s) { s[si] *= factor; }
    extents.push(d3.extent(s));
  }
  y.domain(d3.extent(d3.merge(extents)));

  var updateSel = chart.selectAll('path.series').data(ss);
  updateSel.enter().append('path').classed('series', true)
  updateSel
    .attr("stroke", d3.scale.category10())
    .transition()
      .duration(90)
      .ease("linear")
      .attr('d', d3.svg.line()
        // .interpolate('basis')
        .x(function(d,i) { return x(i); })
        .y(y) );

  if (!guides) { return; }
  guides
    .attr("visibility", "visible")
    .transition()
      .duration(90)
      .ease("linear")
      .attr("transform", "translate("+(x(x0))+",0)")
  yGuides
    .transition()
      .duration(90)
      .ease("linear")
      .attr("transform", "translate(0,"+y(1)+")")

 }

 </script>
	<!DOCTYPE html>
	<title>series normalization per mouse-x (in d3.js)</title>
	<style>
	svg .chart {
	fill: none;
	stroke: #000;
	stroke-width: 2px;
	}
	svg rect.mouse {
	fill: none;
	pointer-events: all;
	}

	svg .guides {
	stroke-width: 1px;
	}
	svg .guides line {
	stroke: #BBC;
	shape-rendering: crispEdges;
	}
	svg .guides circle {
	fill: #BBC;
	stroke: #348;
	opacity: 0.3;
	}
	</style>

	<body></body>

	<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js" charset="utf-8"></script>
	<script>

	var n=100, seriesList = [];
	pushSeries(function(i) { return Math.sin(iMath.PI/(n0.2))+2; });
	pushSeries(function(i) { return Math.cos(iMath.PI/(n0.3))+2; });
	pushSeries(function(i) { return Math.cos(iMath.PI/(n0.15))/2+3*i/n+2; });
	pushSeries(function(i) { return Math.pow(i/n,1.8)+1; });

	var width = 960,
	height = 500;

	var x = d3.scale.linear().range([0, width]);
	var y = d3.scale.linear().range([height, 0]);
	var series = seriesList[0];
	x.domain([0, n]);

	var svg = d3.select("body").append("svg")
	.attr("width", width)
	.attr("height", height);
	var chart = svg.append('g').classed('chart', true);

	var guides;
	effectScaledPaths(0);

	guides = chart.append("svg:g")
	.classed("guides", true);
	guides.append("svg:line")
	.attr("y1",height);
	var yGuides = guides.append("svg:g")
	yGuides.append("svg:circle")
	.attr("r",7);
	yGuides.append("svg:line")
	.attr("x1",-20)
	.attr("x2",+20);



	svg.append("rect").classed("mouse", true)
	.attr("width", width)
	.attr("height", height)
	.on("mousemove", mousemove)
	.on("mouseout", mouseout);

	mouseout();



	function pushSeries(fn) {
	var s = [];
	seriesList.push(s);
	for (var i=0;i<n;i++) { s.push(fn(i)); }
	}

	function mousemove() {
	effectScaledPaths(Math.floor(x.invert(d3.mouse(this)[0]))); // TODO: bisect when x domain isn't index?
	}
	function mouseout() {
	// guides.attr("visibility", "hidden");
	}

	var lastX0 = 0;
	function effectScaledPaths(x0) {
	/*
	Scale each series to be proportional to its value at x0,
	such that all series cross at some single point at mouse.x,
	setting y.domain to extent of extents of all so-scaled series (i.e., global max,min).
	*/

	if (x0 === lastX0) { return; }
	lastX0 = x0;

	var ss = seriesList.slice();
	var extents = [];
	for (var ssi in ss) {
	var s = ss[ssi] = ss[ssi].slice();
	var factor = 1.0 / s[x0]; // but nothing is proportional to a value of 0
	for (var si in s) { s[si] *= factor; }
	extents.push(d3.extent(s));
	}
	y.domain(d3.extent(d3.merge(extents)));

	var updateSel = chart.selectAll('path.series').data(ss);
	updateSel.enter().append('path').classed('series', true)
	updateSel
	.attr("stroke", d3.scale.category10())
	.transition()
	.duration(90)
	.ease("linear")
	.attr('d', d3.svg.line()
	// .interpolate('basis')
	.x(function(d,i) { return x(i); })
	.y(y) );

	if (!guides) { return; }
	guides
	.attr("visibility", "visible")
	.transition()
	.duration(90)
	.ease("linear")
	.attr("transform", "translate("+(x(x0))+",0)")
	yGuides
	.transition()
	.duration(90)
	.ease("linear")
	.attr("transform", "translate(0,"+y(1)+")")

	}

	</script>