radar chart with smallest area on top

.block

license: CC0-1.0

README.md

this version tries out radarChart.js with a new dataset and makes some improvements.

+ parameter-ize the axisName and value fields:

var radarChartOptions = {
  w: width,
  h: height,
  margin: margin,
  maxValue: 1,
  wrapWidth: 135,
  levels: 5,
  roundStrokes: true,
  color: color,
  axisName: "statement",
  value: "percentCorrect"
};

+ subtract Math.PI/2 from angleSlice*i when drawing the radial axis lines so that they line up with the axis label text and the points (it seems this is only a problem your dataset has a number of elements that is not divisible by four)

+ sort the data for the areas from largest to smallest by average value (an approximation of actual blob area) so that that the smallest area is drawn last and therefore appears on top

//Calculate the average value for each area
data.forEach(function(d){
	d[value + "Average"] = d3.mean(d.values, function(e){ return e[value] }); 
})

//Sort
data = data.sort(function(a, b){
	var a = a[value + "Average"],
			b = b[value + "Average"];
	return b - a;
  })

an iteration on the bl.ock radar chart for nested data by @micahstubbs

and a further iteration on the bl.ock Radar Chart Redesign created by @nbremer

the data is a subset of table 7-8: Correct answers to factual knowledge questions in physical and biological sciences, by country/region: Most recent year from the US National Science Foundation

data.json

[
  {
    "key": "China",
    "values": [
      {
        "statement": "The continents have been moving their location for millions of years and will continue to move.",
        "answer": "true",
        "percentCorrect": 0.5,
        "country": "China",
        "surveyYear": 2010
      },
      {
        "statement": "All radioactivity is man-made.",
        "answer": "false",
        "percentCorrect": 0.48,
        "country": "China",
        "surveyYear": 2010
      },
      {
        "statement": "Electrons are smaller than atoms.",
        "answer": "true",
        "percentCorrect": 0.27,
        "country": "China",
        "surveyYear": 2010
      },
      {
        "statement": "Lasers work by focusing sound waves.",
        "answer": "false",
        "percentCorrect": 0.23,
        "country": "China",
        "surveyYear": 2010
      },
      {
        "statement": "It is the father’s gene that decides whether the baby is a boy or a girl.",
        "answer": "true",
        "percentCorrect": 0.58,
        "country": "China",
        "surveyYear": 2010
      },
      {
        "statement": "Antibiotics kill viruses as well as bacteria.",
        "answer": "false",
        "percentCorrect": 0.28,
        "country": "China",
        "surveyYear": 2010
      }
    ]
  },
  {
    "key": "Japan",
    "values": [
      {
        "statement": "The continents have been moving their location for millions of years and will continue to move.",
        "answer": "true",
        "percentCorrect": 0.88,
        "country": "Japan",
        "surveyYear": 2011
      },
      {
        "statement": "All radioactivity is man-made.",
        "answer": "false",
        "percentCorrect": 0.69,
        "country": "Japan",
        "surveyYear": 2011
      },
      {
        "statement": "Electrons are smaller than atoms.",
        "answer": "true",
        "percentCorrect": 0.32,
        "country": "Japan",
        "surveyYear": 2011
      },
      {
        "statement": "Lasers work by focusing sound waves.",
        "answer": "false",
        "percentCorrect": 0.32,
        "country": "Japan",
        "surveyYear": 2011
      },
      {
        "statement": "It is the father’s gene that decides whether the baby is a boy or a girl.",
        "answer": "true",
        "percentCorrect": 0.29,
        "country": "Japan",
        "surveyYear": 2011
      },
      {
        "statement": "Antibiotics kill viruses as well as bacteria.",
        "answer": "false",
        "percentCorrect": 0.33,
        "country": "Japan",
        "surveyYear": 2011
      }
    ]
  },
  {
    "key": "South Korea",
    "values": [
      {
        "statement": "The continents have been moving their location for millions of years and will continue to move.",
        "answer": "true",
        "percentCorrect": 0.87,
        "country": "South Korea",
        "surveyYear": 2004
      },
      {
        "statement": "All radioactivity is man-made.",
        "answer": "false",
        "percentCorrect": 0.48,
        "country": "South Korea",
        "surveyYear": 2004
      },
      {
        "statement": "Electrons are smaller than atoms.",
        "answer": "true",
        "percentCorrect": 0.46,
        "country": "South Korea",
        "surveyYear": 2004
      },
      {
        "statement": "Lasers work by focusing sound waves.",
        "answer": "false",
        "percentCorrect": 0.31,
        "country": "South Korea",
        "surveyYear": 2004
      },
      {
        "statement": "It is the father’s gene that decides whether the baby is a boy or a girl.",
        "answer": "true",
        "percentCorrect": 0.59,
        "country": "South Korea",
        "surveyYear": 2004
      },
      {
        "statement": "Antibiotics kill viruses as well as bacteria.",
        "answer": "false",
        "percentCorrect": 0.3,
        "country": "South Korea",
        "surveyYear": 2004
      }
    ]
  }
]

index.html

<!DOCTYPE html>
<html>
	<head>
		<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/ >
		<title>Smoothed D3.js Radar Chart</title>

		<!-- Google fonts -->
		<link href='https://fonts.googleapis.com/css?family=Open+Sans:400,300' rel='stylesheet' type='text/css'>
		<link href='https://fonts.googleapis.com/css?family=Raleway' rel='stylesheet' type='text/css'>

		<!-- D3.js -->
		<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js" charset="utf-8"></script>
		
		<style>
			body {
				font-family: 'Open Sans', sans-serif;
				font-size: 11px;
				font-weight: 300;
				fill: #242424;
				text-align: center;
				text-shadow: 0 1px 0 #fff, 1px 0 0 #fff, -1px 0 0 #fff, 0 -1px 0 #fff;
				cursor: default;
			}
			
			.legend {
				font-family: 'Raleway', sans-serif;
				fill: #333333;
			}
			
			.tooltip {
				fill: #333333;
			}
		</style>
	
	</head>
	<body>

		<div class="radarChart"></div>

		<script src="radarChart.js"></script>	
		<script>
			////////////////////////////////////////////////////////////// 
			//////////////////////// Set-Up ////////////////////////////// 
			////////////////////////////////////////////////////////////// 

			var margin = {top: 100, right: 100, bottom: 100, left: 100},
				width = Math.min(700, window.innerWidth - 10) - margin.left - margin.right,
				height = Math.min(width, window.innerHeight - margin.top - margin.bottom - 20);
					
			////////////////////////////////////////////////////////////// 
			//////////////////// Draw the Chart ////////////////////////// 
			////////////////////////////////////////////////////////////// 

			var color = d3.scale.ordinal()
				.range(["#EDC951","#CC333F","#00A0B0"]);
				
			var radarChartOptions = {
			  w: width,
			  h: height,
			  margin: margin,
			  maxValue: 1,
			  wrapWidth: 135,
			  levels: 5,
			  roundStrokes: true,
			  color: color,
			  axisName: "statement",
			  value: "percentCorrect"
			};

			//Load the data and Call function to draw the Radar chart
			d3.json("data.json", function(error, data){
				RadarChart(".radarChart", data, radarChartOptions);
			});
			
		</script>
	</body>
</html>

radarChart.js

/////////////////////////////////////////////////////////
/////////////// The Radar Chart Function ////////////////
/////////////// Written by Nadieh Bremer ////////////////
////////////////// VisualCinnamon.com ///////////////////
/////////// Inspired by the code of alangrafu ///////////
/////////////////////////////////////////////////////////
	
function RadarChart(id, data, options) {
	var cfg = {
	 w: 600,				//Width of the circle
	 h: 600,				//Height of the circle
	 margin: {top: 20, right: 20, bottom: 20, left: 20}, //The margins around the circle
	 levels: 3,				//How many levels or inner circles should there be drawn
	 maxValue: 0, 				//What is the value that the biggest circle will represent
	 labelFactor: 1.25, 			//How much farther than the radius of the outer circle should the labels be placed
	 wrapWidth: 60, 			//The number of pixels after which a label needs to be given a new line
	 opacityArea: 0.35, 			//The opacity of the area of the blob
	 dotRadius: 4, 				//The size of the colored circles of each blog
	 opacityCircles: 0.1, 			//The opacity of the circles of each blob
	 strokeWidth: 2, 			//The width of the stroke around each blob
	 roundStrokes: false,			//If true the area and stroke will follow a round path (cardinal-closed)
	 color: d3.scale.category10(),		//Color function
	 axisName: "axis",
	 value: "value",
	 sortAreas: true,
	};
	
	//Put all of the options into a variable called cfg
	if('undefined' !== typeof options){
	  for(var i in options){
		if('undefined' !== typeof options[i]){ cfg[i] = options[i]; }
	  }//for i
	}//if

	//Map the fields specified in the configuration 
	// to the axis and value variables
	var axisName = cfg["axisName"],
			value = cfg["value"];

	//Calculate the average value for each area
	data.forEach(function(d){
		d[value + "Average"] = d3.mean(d.values, function(e){ return e[value] }); 
	})

	//Sort the data for the areas from largest to smallest
	//by average value as an approximation of actual blob area
	//so that that the smallest area is drawn last
	//and therefore appears on top
	data = data.sort(function(a, b){
		var a = a[value + "Average"],
				b = b[value + "Average"];
		return b - a;
	})
	
	//Convert the nested data passed in
	// into an array of values arrays
	data = data.map(function(d) { return d.values })

	//If the supplied maxValue is smaller than the actual one, replace by the max in the data
	var maxValue = Math.max(cfg.maxValue, d3.max(data, function(i){
		return d3.max(i.map(
			function(o){ return o[value]; }
		))
	}));
		
	var allAxis = (data[0].map(function(d, i){ return d[axisName] })),	//Names of each axis
		total = allAxis.length,					//The number of different axes
		radius = Math.min(cfg.w/2, cfg.h/2), 			//Radius of the outermost circle
		Format = d3.format('%'),			 	//Percentage formatting
		angleSlice = Math.PI * 2 / total;			//The width in radians of each "slice"

	//Scale for the radius
	var rScale = d3.scale.linear()
		.range([0, radius])
		.domain([0, maxValue]);
		
	/////////////////////////////////////////////////////////
	//////////// Create the container SVG and g /////////////
	/////////////////////////////////////////////////////////

	//Remove whatever chart with the same id/class was present before
	d3.select(id).select("svg").remove();
	
	//Initiate the radar chart SVG
	var svg = d3.select(id).append("svg")
			.attr("width",  cfg.w + cfg.margin.left + cfg.margin.right)
			.attr("height", cfg.h + cfg.margin.top + cfg.margin.bottom)
			.attr("class", "radar"+id);
	//Append a g element		
	var g = svg.append("g")
			.attr("transform", "translate(" + (cfg.w/2 + cfg.margin.left) + "," + (cfg.h/2 + cfg.margin.top) + ")");
	
	/////////////////////////////////////////////////////////
	////////// Glow filter for some extra pizzazz ///////////
	/////////////////////////////////////////////////////////
	
	//Filter for the outside glow
	var filter = g.append('defs').append('filter').attr('id','glow'),
		feGaussianBlur = filter.append('feGaussianBlur').attr('stdDeviation','2.5').attr('result','coloredBlur'),
		feMerge = filter.append('feMerge'),
		feMergeNode_1 = feMerge.append('feMergeNode').attr('in','coloredBlur'),
		feMergeNode_2 = feMerge.append('feMergeNode').attr('in','SourceGraphic');

	/////////////////////////////////////////////////////////
	/////////////// Draw the Circular grid //////////////////
	/////////////////////////////////////////////////////////
	
	//Wrapper for the grid & axes
	var axisGrid = g.append("g").attr("class", "axisWrapper");
	
	//Draw the background circles
	axisGrid.selectAll(".levels")
	   .data(d3.range(1,(cfg.levels+1)).reverse())
	   .enter()
		.append("circle")
		.attr("class", "gridCircle")
		.attr("r", function(d, i){return radius/cfg.levels*d;})
		.style("fill", "#CDCDCD")
		.style("stroke", "#CDCDCD")
		.style("fill-opacity", cfg.opacityCircles)
		.style("filter" , "url(#glow)");

	//Text indicating at what % each level is
	axisGrid.selectAll(".axisLabel")
	   .data(d3.range(1,(cfg.levels+1)).reverse())
	   .enter().append("text")
	   .attr("class", "axisLabel")
	   .attr("x", 4)
	   .attr("y", function(d){return -d*radius/cfg.levels;})
	   .attr("dy", "0.4em")
	   .style("font-size", "10px")
	   .attr("fill", "#737373")
	   .text(function(d,i) { return Format(maxValue * d/cfg.levels); });

	/////////////////////////////////////////////////////////
	//////////////////// Draw the axes //////////////////////
	/////////////////////////////////////////////////////////
	
	//Create the straight lines radiating outward from the center
	var axis = axisGrid.selectAll(".axis")
		.data(allAxis)
		.enter()
		.append("g")
		.attr("class", "axis");
	//Append the lines
	axis.append("line")
		.attr("x1", 0)
		.attr("y1", 0)
		.attr("x2", function(d, i){ return rScale(maxValue*1.1) * Math.cos(angleSlice*i - Math.PI/2); })
		.attr("y2", function(d, i){ return rScale(maxValue*1.1) * Math.sin(angleSlice*i - Math.PI/2); })
		.attr("class", "line")
		.style("stroke", "white")
		.style("stroke-width", "2px");

	//Append the labels at each axis
	axis.append("text")
		.attr("class", "legend")
		.style("font-size", "11px")
		.attr("text-anchor", "middle")
		.attr("dy", "0.35em")
		.attr("x", function(d, i){ return rScale(maxValue * cfg.labelFactor) * Math.cos(angleSlice*i - Math.PI/2); })
		.attr("y", function(d, i){ return rScale(maxValue * cfg.labelFactor) * Math.sin(angleSlice*i - Math.PI/2); })
		.text(function(d){return d})
		.call(wrap, cfg.wrapWidth);

	/////////////////////////////////////////////////////////
	///////////// Draw the radar chart blobs ////////////////
	/////////////////////////////////////////////////////////
	
	//The radial line function
	var radarLine = d3.svg.line.radial()
		.interpolate("linear-closed")
		.radius(function(d) { return rScale(d[value]); })
		.angle(function(d,i) {	return i*angleSlice; });
		
	if(cfg.roundStrokes) {
		radarLine.interpolate("cardinal-closed");
	}
				
	//Create a wrapper for the blobs	
	var blobWrapper = g.selectAll(".radarWrapper")
		.data(data)
		.enter().append("g")
		.attr("class", "radarWrapper");
			
	//Append the backgrounds	
	blobWrapper
		.append("path")
		.attr("class", "radarArea")
		.attr("d", function(d,i) { return radarLine(d); })
		.style("fill", function(d,i) { return cfg.color(i); })
		.style("fill-opacity", cfg.opacityArea)
		.on('mouseover', function (d,i){
			//Dim all blobs
			d3.selectAll(".radarArea")
				.transition().duration(200)
				.style("fill-opacity", 0.1); 
			//Bring back the hovered over blob
			d3.select(this)
				.transition().duration(200)
				.style("fill-opacity", 0.7);	
		})
		.on('mouseout', function(){
			//Bring back all blobs
			d3.selectAll(".radarArea")
				.transition().duration(200)
				.style("fill-opacity", cfg.opacityArea);
		});
		
	//Create the outlines	
	blobWrapper.append("path")
		.attr("class", "radarStroke")
		.attr("d", function(d,i) { return radarLine(d); })
		.style("stroke-width", cfg.strokeWidth + "px")
		.style("stroke", function(d,i) { return cfg.color(i); })
		.style("fill", "none")
		.style("filter" , "url(#glow)");		
	
	//Append the circles
	blobWrapper.selectAll(".radarCircle")
		.data(function(d,i) { return d; })
		.enter().append("circle")
		.attr("class", "radarCircle")
		.attr("r", cfg.dotRadius)
		.attr("cx", function(d,i){ return rScale(d[value]) * Math.cos(angleSlice*i - Math.PI/2); })
		.attr("cy", function(d,i){ return rScale(d[value]) * Math.sin(angleSlice*i - Math.PI/2); })
		.style("fill", function(d,i,j) { return cfg.color(j); })
		.style("fill-opacity", 0.8);

	/////////////////////////////////////////////////////////
	//////// Append invisible circles for tooltip ///////////
	/////////////////////////////////////////////////////////
	
	//Wrapper for the invisible circles on top
	var blobCircleWrapper = g.selectAll(".radarCircleWrapper")
		.data(data)
		.enter().append("g")
		.attr("class", "radarCircleWrapper");
		
	//Append a set of invisible circles on top for the mouseover pop-up
	blobCircleWrapper.selectAll(".radarInvisibleCircle")
		.data(function(d,i) { return d; })
		.enter().append("circle")
		.attr("class", "radarInvisibleCircle")
		.attr("r", cfg.dotRadius*1.5)
		.attr("cx", function(d,i){ return rScale(d[value]) * Math.cos(angleSlice*i - Math.PI/2); })
		.attr("cy", function(d,i){ return rScale(d[value]) * Math.sin(angleSlice*i - Math.PI/2); })
		.style("fill", "none")
		.style("pointer-events", "all")
		.on("mouseover", function(d,i) {
			newX =  parseFloat(d3.select(this).attr('cx')) - 10;
			newY =  parseFloat(d3.select(this).attr('cy')) - 10;
					
			tooltip
				.attr('x', newX)
				.attr('y', newY)
				.text(Format(d[value]))
				.transition().duration(200)
				.style('opacity', 1);
		})
		.on("mouseout", function(){
			tooltip.transition().duration(200)
				.style("opacity", 0);
		});
		
	//Set up the small tooltip for when you hover over a circle
	var tooltip = g.append("text")
		.attr("class", "tooltip")
		.style("opacity", 0);
	
	/////////////////////////////////////////////////////////
	/////////////////// Helper Function /////////////////////
	/////////////////////////////////////////////////////////

	//Taken from http://bl.ocks.org/mbostock/7555321
	//Wraps SVG text	
	function wrap(text, width) {
	  text.each(function() {
		var text = d3.select(this),
			words = text.text().split(/\s+/).reverse(),
			word,
			line = [],
			lineNumber = 0,
			lineHeight = 1.4, // ems
			y = text.attr("y"),
			x = text.attr("x"),
			dy = parseFloat(text.attr("dy")),
			tspan = text.text(null).append("tspan").attr("x", x).attr("y", y).attr("dy", dy + "em");
			
		while (word = words.pop()) {
		  line.push(word);
		  tspan.text(line.join(" "));
		  if (tspan.node().getComputedTextLength() > width) {
			line.pop();
			tspan.text(line.join(" "));
			line = [word];
			tspan = text.append("tspan").attr("x", x).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
		  }
		}
	  });
	}//wrap	
	
}//RadarChart

thumbnail.png