I'm trying to display labels with its value and tooltip in semi donut pie chart using D3 JS.
I'm not able to display labels and their values at the simultaneously.
And how can I add the tooltip on this chart?
I tried implementing this fiddle.
https://jsfiddle.net/SampathPerOxide/hcvuqjt2/6/
var width = 400;
var height = 300; //this is the double because are showing just the half of the pie
var radius = Math.min(width, height) / 2;
var labelr = radius + 30; // radius for label anchor
//array of colors for the pie (in the same order as the dataset)
var color = d3.scale
.ordinal()
.range(['#2b5eac', '#0dadd3', '#ffea61', '#ff917e', '#ff3e41']);
data = [
{ label: 'CDU', value: 10 },
{ label: 'SPD', value: 15 },
{ label: 'Die Grünen', value: 8 },
{ label: 'Die Mitte', value: 1 },
{ label: 'Frei Wähler', value: 3 }
];
var vis = d3
.select('#chart')
.append('svg') //create the SVG element inside the <body>
.data([data]) //associate our data with the document
.attr('width', width) //set the width and height of our visualization (these will be attributes of the <svg> tag
.attr('height', height)
.append('svg:g') //make a group to hold our pie chart
.attr('transform', 'translate(' + width / 2 + ',' + height / 2 + ')'); //move the center of the pie chart from 0, 0 to radius, radius
var arc = d3.svg
.arc() //this will create <path> elements for us using arc data
.innerRadius(79)
// .outerRadius(radius);
.outerRadius(radius - 10); // full height semi pie
//.innerRadius(0);
var pie = d3.layout
.pie() //this will create arc data for us given a list of values
.startAngle(-90 * (Math.PI / 180))
.endAngle(90 * (Math.PI / 180))
.padAngle(0.02) // some space between slices
.sort(null) //No! we don't want to order it by size
.value(function(d) {
return d.value;
}); //we must tell it out to access the value of each element in our data array
var arcs = vis
.selectAll('g.slice') //this selects all <g> elements with class slice (there aren't any yet)
.data(pie) //associate the generated pie data (an array of arcs, each having startAngle, endAngle and value properties)
.enter() //this will create <g> elements for every "extra" data element that should be associated with a selection. The result is creating a <g> for every object in the data array
.append('svg:g') //create a group to hold each slice (we will have a <path> and a <text> element associated with each slice)
.attr('class', 'slice'); //allow us to style things in the slices (like text)
arcs
.append('svg:path')
.attr('fill', function(d, i) {
return color(i);
}) //set the color for each slice to be chosen from the color function defined above
.attr('d', arc); //this creates the actual SVG path using the associated data (pie) with the arc drawing function
arcs
.append('svg:text')
.attr('class', 'labels') //add a label to each slice
.attr('fill', 'grey')
.attr('transform', function(d) {
var c = arc.centroid(d),
xp = c[0],
yp = c[1],
// pythagorean theorem for hypotenuse
hp = Math.sqrt(xp * xp + yp * yp);
return 'translate(' + (xp / hp) * labelr + ',' + (yp / hp) * labelr + ')';
})
.attr('text-anchor', 'middle') //center the text on it's origin
.text(function(d, i) {
return data[i].value;
})
.text(function(d, i) {
return data[i].label;
}); //get the label from our original data array
I'm trying to achieve this. https://i.imgur.com/kTXeAXt.png
First of all, if you console.log the data (from .data(pie)) you used for displaying text label and value, you will noticed that label can only be access via d.data.label instead of data[i].label.
{data: {label: "Frei Wähler", value: 3}, value: 3, startAngle: 1.304180706233562, endAngle: 1.5707963267948966, padAngle: 0.02}
Therefore in order to correctly display both label and value, the code should be:
arcs.append("svg:text")
.attr("class", "labels")//add a label to each slice
.attr("fill", "grey")
.attr("transform", function(d) {
var c = arc.centroid(d),
xp = c[0],
yp = c[1],
// pythagorean theorem for hypotenuse
hp = Math.sqrt(xp*xp + yp*yp);
return "translate(" + (xp/hp * labelr) + ',' +
(yp/hp * labelr) + ")";
})
.attr("text-anchor", "middle") //center the text on it's origin
.text(function(d, i) { return d.data.value; })
.text(function(d, i) { return d.data.label; });
How to add tooltip
As for how to create d3 tooltip, it needs a little of css, html and then add d3 event handling.
1) add the following html to your index.html:
<div id="tooltip" class="hidden"><p id="tooltip-data"></p></div>
2) add a little bit css to set the div to position:absolute and hide the tooltip with display:none, and gives it a little bit styling per your preference:
<style>
#tooltip {
position:absolute;
background: #ffffe0;
color: black;
width: 180px;
border-radius: 3px;
box-shadow: 2px 2px 6px rgba(40, 40, 40, 0.5);
}
#tooltip.hidden {
display:none;
}
#tooltip p {
margin: 0px;
padding: 8px;
font-size: 12px;
}
3) We then add mouseover event handler, the idea is when the mouse is over the chart, we will set the top and left properties of the #tooltip css style to where the mouse is, and set the css display property to show the tooltip.
//tooltip
arcs.on("mouseover", function(d) {
d3.select("#tooltip")
.style("left", `${d3.event.clientX}px`)
.style("top", `${d3.event.clientY}px`)
.classed("hidden", false);
d3.select("#tooltip-data")
.html(`Label: ${d.data.label}<br>Value: ${d.data.value}`);
});
arcs.on("mouseout", function(d) {
d3.select("#tooltip")
.classed("hidden", true);
});
selection.text([value])
If a value is specified, sets the text content to the specified value on all selected elements, replacing any existing child elements.
So you are setting the text content with the value and immediately replacing it with the label.
What you can do is return a combined string from the value and label of your datum in a template literal like this:
.text(function(d, i) { return `${data[i].value} - ${data[i].label}`; })
var width = 400;
var height = 300; //this is the double because are showing just the half of the pie
var radius = Math.min(width, height) / 2;
var labelr = radius + 30; // radius for label anchor
//array of colors for the pie (in the same order as the dataset)
var color = d3.scale.ordinal()
.range(['#2b5eac', '#0dadd3', '#ffea61', '#ff917e', '#ff3e41']);
data = [{
label: 'CDU',
value: 10
},
{
label: 'SPD',
value: 15
},
{
label: 'Die Grünen',
value: 8
},
{
label: 'Die Mitte',
value: 1
},
{
label: 'Frei Wähler',
value: 3
}
];
var vis = d3.select("#chart")
.append("svg") //create the SVG element inside the <body>
.data([data]) //associate our data with the document
.attr("width", width) //set the width and height of our visualization (these will be attributes of the <svg> tag
.attr("height", height)
.append("svg:g") //make a group to hold our pie chart
.attr('transform', 'translate(' + (width / 2) + ',' + (height / 2) + ')'); //move the center of the pie chart from 0, 0 to radius, radius
var arc = d3.svg.arc() //this will create <path> elements for us using arc data
.innerRadius(79)
// .outerRadius(radius);
.outerRadius(radius - 10) // full height semi pie
//.innerRadius(0);
var pie = d3.layout.pie() //this will create arc data for us given a list of values
.startAngle(-90 * (Math.PI / 180))
.endAngle(90 * (Math.PI / 180))
.padAngle(.02) // some space between slices
.sort(null) //No! we don't want to order it by size
.value(function(d) {
return d.value;
}); //we must tell it out to access the value of each element in our data array
var arcs = vis.selectAll("g.slice") //this selects all <g> elements with class slice (there aren't any yet)
.data(pie) //associate the generated pie data (an array of arcs, each having startAngle, endAngle and value properties)
.enter() //this will create <g> elements for every "extra" data element that should be associated with a selection. The result is creating a <g> for every object in the data array
.append("svg:g") //create a group to hold each slice (we will have a <path> and a <text> element associated with each slice)
.attr("class", "slice"); //allow us to style things in the slices (like text)
arcs.append("svg:path")
.attr("fill", function(d, i) {
return color(i);
}) //set the color for each slice to be chosen from the color function defined above
.attr("d", arc); //this creates the actual SVG path using the associated data (pie) with the arc drawing function
arcs.append("svg:text")
.attr("class", "labels") //add a label to each slice
.attr("fill", "grey")
.attr("transform", function(d) {
var c = arc.centroid(d),
xp = c[0],
yp = c[1],
// pythagorean theorem for hypotenuse
hp = Math.sqrt(xp * xp + yp * yp);
return "translate(" + (xp / hp * labelr) + ',' +
(yp / hp * labelr) + ")";
})
.attr("text-anchor", "middle") //center the text on it's origin
.text(function(d, i) {
return `${data[i].value} - ${data[i].label}`;
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<div id="chart" style="width: 330px;height: 200px;"></div>
Edit:
If you want the two text strings to be on separate lines you would have to append some <tspan> elements and position them.
var width = 400;
var height = 300; //this is the double because are showing just the half of the pie
var radius = Math.min(width, height) / 2;
var labelr = radius + 30; // radius for label anchor
//array of colors for the pie (in the same order as the dataset)
var color = d3.scale.ordinal()
.range(['#2b5eac', '#0dadd3', '#ffea61', '#ff917e', '#ff3e41']);
data = [{
label: 'CDU',
value: 10
},
{
label: 'SPD',
value: 15
},
{
label: 'Die Grünen',
value: 8
},
{
label: 'Die Mitte',
value: 1
},
{
label: 'Frei Wähler',
value: 3
}
];
var vis = d3.select("#chart")
.append("svg") //create the SVG element inside the <body>
.data([data]) //associate our data with the document
.attr("width", width) //set the width and height of our visualization (these will be attributes of the <svg> tag
.attr("height", height)
.append("svg:g") //make a group to hold our pie chart
.attr('transform', 'translate(' + (width / 2) + ',' + (height / 2) + ')'); //move the center of the pie chart from 0, 0 to radius, radius
var arc = d3.svg.arc() //this will create <path> elements for us using arc data
.innerRadius(79)
// .outerRadius(radius);
.outerRadius(radius - 10) // full height semi pie
//.innerRadius(0);
var pie = d3.layout.pie() //this will create arc data for us given a list of values
.startAngle(-90 * (Math.PI / 180))
.endAngle(90 * (Math.PI / 180))
.padAngle(.02) // some space between slices
.sort(null) //No! we don't want to order it by size
.value(function(d) {
return d.value;
}); //we must tell it out to access the value of each element in our data array
var arcs = vis.selectAll("g.slice") //this selects all <g> elements with class slice (there aren't any yet)
.data(pie) //associate the generated pie data (an array of arcs, each having startAngle, endAngle and value properties)
.enter() //this will create <g> elements for every "extra" data element that should be associated with a selection. The result is creating a <g> for every object in the data array
.append("svg:g") //create a group to hold each slice (we will have a <path> and a <text> element associated with each slice)
.attr("class", "slice"); //allow us to style things in the slices (like text)
arcs.append("svg:path")
.attr("fill", function(d, i) {
return color(i);
}) //set the color for each slice to be chosen from the color function defined above
.attr("d", arc); //this creates the actual SVG path using the associated data (pie) with the arc drawing function
const textEl = arcs.append("svg:text")
.attr("class", "labels") //add a label to each slice
.attr("fill", "grey")
.attr("transform", function(d) {
var c = arc.centroid(d),
xp = c[0],
yp = c[1],
// pythagorean theorem for hypotenuse
hp = Math.sqrt(xp * xp + yp * yp);
return "translate(" + (xp / hp * labelr) + ',' +
(yp / hp * labelr) + ")";
})
.attr("text-anchor", "middle"); //center the text on it's origin
textEl.append('tspan')
.text(function(d, i) {
return data[i].label;
});
textEl.append('tspan')
.text(function(d, i) {
return data[i].value;
})
.attr('x', '0')
.attr('dy', '1.2em');
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<div id="chart" style="width: 330px;height: 200px;"></div>
Related
I have made two separate graph on separate page of Bar and pie chart respectively and now i wanted to combine this two graph in the single page so that I can have a dashboard. but when i start to combine to two graph in the main page its not happening and they overlap of each other.
Code:
https://github.com/Mustafa2911/d3-design/blob/main/combine.html
Combine file contain: Code of both pie and bar chart.
Bar file contain: Code of bar chart.
Pie chart contain: Code of pie chart.
Tried this with your code.
Scroll to see the bar graph axis.
NOTE: The bar graph data will not be available ∵ it is from the demo1.csv file in your repository.
Hope this helps.
<!DOCTYPE html>
<meta charset="utf-8">
<head>
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>
<style>
#my_dataviz {
display: inline-block;
width: 50%;
}
</style>
</head>
<body>
<div id="my_dataviz"></div>
<script>
// set the dimensions and margins of the graph
var width = 800
height = 450
margin = 40
// The radius of the pieplot is half the width or half the height (smallest one). I subtract a bit of margin.
var radius = Math.min(width, height) / 2 - margin
// append the svg object to the div called 'my_dataviz'
var svg = d3.select("#my_dataviz")
.append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
// Create dummy data
var data = {
Corporation_Tax: 15,
Income_Tax: 15,
Customs: 5,
Union_Excise_Duties: 7,
Good_and_Service_tax: 16,
Non_tax_Revenue: 5,
Non_Dept_Capital_Receipt: 2,
Borrowings_Liabilities: 35
}
// set the color scale
var color = d3.scaleOrdinal()
.domain(["a", "b", "c", "d", "e", "f", "g", "h"])
.range(d3.schemeSet1);
// Compute the position of each group on the pie:
var pie = d3.pie()
.sort(null) // Do not sort group by size
.value(function(d) {
return d.value;
})
var data_ready = pie(d3.entries(data))
// The arc generator
var arc = d3.arc()
.innerRadius(radius * 0.5) // This is the size of the donut hole
.outerRadius(radius * 0.8)
// Another arc that won't be drawn. Just for labels positioning
var outerArc = d3.arc()
.innerRadius(radius * 0.9)
.outerRadius(radius * 0.9)
// Build the pie chart: Basically, each part of the pie is a path that we build using the arc function.
svg
.selectAll('allSlices')
.data(data_ready)
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function(d) {
return (color(d.data.key))
})
.attr("stroke", "white")
.style("stroke-width", "2px")
.style("opacity", 1)
// Add the polylines between chart and labels:
svg
.selectAll('allPolylines')
.data(data_ready)
.enter()
.append('polyline')
.attr("stroke", "black")
.style("fill", "none")
.attr("stroke-width", 1)
.attr('points', function(d) {
var posA = arc.centroid(d) // line insertion in the slice
var posB = outerArc.centroid(d) // line break: we use the other arc generator that has been built only for that
var posC = outerArc.centroid(d); // Label position = almost the same as posB
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2 // we need the angle to see if the X position will be at the extreme right or extreme left
posC[0] = radius * 0.95 * (midangle < Math.PI ? 1 : -1); // multiply by 1 or -1 to put it on the right or on the left
return [posA, posB, posC]
})
// Add the polylines between chart and labels:
svg
.selectAll('allLabels')
.data(data_ready)
.enter()
.append('text')
.text(function(d) {
console.log(d.data.key);
return d.data.key
})
.attr('transform', function(d) {
var pos = outerArc.centroid(d);
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
pos[0] = radius * 0.99 * (midangle < Math.PI ? 1 : -1);
return 'translate(' + pos + ')';
})
.style('text-anchor', function(d) {
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
return (midangle < Math.PI ? 'start' : 'end')
})
</script>
<style>
#my_dataviz {
display: inline-block;
width: 50%;
}
</style>
<div id="my_dataviz_es"></div>
<script>
// set the dimensions and margins of the graph
var margin = {
top: 20,
right: 30,
bottom: 40,
left: 160
},
width = 460,
height = 400;
// append the svg object to the body of the page
var svg = d3.select("#my_dataviz_es")
.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 + ")");
// Parse the Data
d3.csv("demo1.csv", function(data) {
// Add X axis
var x = d3.scaleLinear()
.domain([0, 550000])
.range([0, width]);
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x))
.selectAll("text")
.attr("transform", "translate(-10,0)rotate(-45)")
.style("text-anchor", "end");
// Y axis
var y = d3.scaleBand()
.range([0, height])
.domain(data.map(function(d) {
return d.Country;
}))
.padding(.1);
svg.append("g")
.call(d3.axisLeft(y))
//Bars
svg.selectAll("myRect")
.data(data)
.enter()
.append("rect")
.attr("x", x(0))
.attr("y", function(d) {
return y(d.Country);
})
.attr("width", function(d) {
return x(d.Value);
})
.attr("height", y.bandwidth())
.attr("fill", "#69b3a2")
// .attr("x", function(d) { return x(d.Country); })
// .attr("y", function(d) { return y(d.Value); })
// .attr("width", x.bandwidth())
// .attr("height", function(d) { return height - y(d.Value); })
// .attr
})
</script>
</body>
</html>
EDIT: See here - https://codepen.io/KZJ/pen/rNpqvdq?editors=1011 - for changes made reg. the below comment
what if I want to have my bar chart at the top and on right side i want to have my pie chart
Changed -
a) Both charts were using the same name 'svg' to d3.select() the divs. This caused the charts to overlap.
b) Modified width, height, transform, and added some border CSS - only for demonstration purposes - It can be removed/edited as required.
FYR this is how it looks now -
I have a .json file with data, and I'd like to make a d3 donut (pie) chart from it. I'm not especially fluent in javascript, and every example I can find either pulls from inline json data or the json file is structured differently than mine (mine is a list of dictionaries; theirs are often single dictionaries). I've been troubleshooting for a few days, and somehow can't land on anything that actually works. Any thoughts/tips?
The example at https://www.d3-graph-gallery.com/graph/donut_label.html uses inline json data to render a donut chart with labels. I've attempted to modify it that code by:
pulling json data from /data/all-facet-digitized.json
pull labels each dictionary's "facet" key ("true" and "false"), and values from each dictionary's "count" key (373977 and 55433).
change the color scale domain to match the facet keys ("true" and "false")
/data/all-facet-digitized.json looks like:
[
{
"count": "55433",
"facet": "true"
},
{
"count": "373977",
"facet": "false"
}
]
Code in the of my html file looks like:
<div id="chart"></div> <!-- div containing the donut chart -->
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
// set the dimensions and margins of the graph
var width = 450
height = 450
margin = 40
// The radius of the pieplot is half the width or half the height (smallest one) minus margin.
var radius = Math.min(width, height) / 2 - margin
// append the svg object to the div called 'chart'
var svg = d3.select("#chart")
.append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
// Parse the Data
d3.json("/data/all-facet-digitized.json", function(data) {
// set the color scale
var color = d3.scaleOrdinal()
.domain(["true","false"])
.range(d3.schemeDark2);
// Compute the position of each group on the pie:
var pie = d3.pie()
.sort(null) // Do not sort group by size
.value(function(d) {return d.count; })
var data_ready = pie(d3.entries(data))
// The arc generator
var arc = d3.arc()
.innerRadius(radius * 0.5) // This is the size of the donut hole
.outerRadius(radius * 0.8)
// Another arc that won't be drawn. Just for labels positioning
var outerArc = d3.arc()
.innerRadius(radius * 0.9)
.outerRadius(radius * 0.9)
// Build the pie chart: Basically, each part of the pie is a path that we build using the arc function.
svg
.selectAll('allSlices')
.data(data_ready)
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function(d){ return(color(d.facet)) })
.attr("stroke", "white")
.style("stroke-width", "2px")
.style("opacity", 0.7)
// Add the polylines between chart and labels:
svg
.selectAll('allPolylines')
.data(data_ready)
.enter()
.append('polyline')
.attr("stroke", "black")
.style("fill", "none")
.attr("stroke-width", 1)
.attr('points', function(d) {
var posA = arc.centroid(d) // line insertion in the slice
var posB = outerArc.centroid(d) // line break: we use the other arc generator that has been built only for that
var posC = outerArc.centroid(d); // Label position = almost the same as posB
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2 // we need the angle to see if the X position will be at the extreme right or extreme left
posC[0] = radius * 0.95 * (midangle < Math.PI ? 1 : -1); // multiply by 1 or -1 to put it on the right or on the left
return [posA, posB, posC]
})
// Add the polylines between chart and labels:
svg
.selectAll('allLabels')
.data(data_ready)
.enter()
.append('text')
.text( function(d) { console.log(d.facet) ; return d.facet} )
.attr('transform', function(d) {
var pos = outerArc.centroid(d);
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
pos[0] = radius * 0.99 * (midangle < Math.PI ? 1 : -1);
return 'translate(' + pos + ')';
})
.style('text-anchor', function(d) {
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
return (midangle < Math.PI ? 'start' : 'end')
})
})
</script>
My result renders as an empty space:
<div id="chart">
<svg width="450" height="450">
<g transform="translate(225,225)"></g>
</svg>
</div>
The schemeDark2 doens't exist in d3 v4. I've replaced it with schemeCategory10:
var color = d3.scaleOrdinal()
.domain(["true","false"])
.range(d3.schemeCategory10);
Since you have an array of objects, you don't need d3.entries. That takes an object and converts it to an array where each key is an item of the array. But since you already have an array here, you can put it directly in pie():
// Compute the position of each group on the pie:
var pie = d3.pie()
.sort(null) // Do not sort group by size
.value(function(d) {return d.count; })
var data_ready = pie(data)
Now that you've got the data, you can access it on any of the functions: try putting console.log(data_ready) to see what's available. You'll see that the data is bound for each object as the .data property. pie() takes an array and puts it in a format that's convenient to make pie charts with.
Say we want to access the facet property: we would access that as item.data.facet. So in your functions, to access, you can do:
svg
.selectAll('allSlices')
.data(data_ready)
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function(d){ return(color(d.data.facet)) })
<head></head>
<div id="chart"></div> <!-- div containing the donut chart -->
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
// set the dimensions and margins of the graph
var width = 450
height = 450
margin = 40
// The radius of the pieplot is half the width or half the height (smallest one) minus margin.
var radius = Math.min(width, height) / 2 - margin
// append the svg object to the div called 'chart'
var svg = d3.select("#chart")
.append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
// Parse the Data
var data = [
{
"count": "55433",
"facet": "true"
},
{
"count": "373977",
"facet": "false"
}
]
// set the color scale
var color = d3.scaleOrdinal()
.domain(["true","false"])
.range(d3.schemeCategory10);
// Compute the position of each group on the pie:
var pie = d3.pie()
.sort(null) // Do not sort group by size
.value(function(d) {return d.count; })
var data_ready = pie(data)
console.log('data_r', data_ready)
// The arc generator
var arc = d3.arc()
.innerRadius(radius * 0.5) // This is the size of the donut hole
.outerRadius(radius * 0.8)
// Another arc that won't be drawn. Just for labels positioning
var outerArc = d3.arc()
.innerRadius(radius * 0.9)
.outerRadius(radius * 0.9)
// Build the pie chart: Basically, each part of the pie is a path that we build using the arc function.
svg
.selectAll('allSlices')
.data(data_ready)
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function(d){ return(color(d.data.facet)) })
.attr("stroke", "white")
.style("stroke-width", "2px")
.style("opacity", 0.7)
// Add the polylines between chart and labels:
svg
.selectAll('allPolylines')
.data(data_ready)
.enter()
.append('polyline')
.attr("stroke", "black")
.style("fill", "none")
.attr("stroke-width", 1)
.attr('points', function(d) {
var posA = arc.centroid(d) // line insertion in the slice
var posB = outerArc.centroid(d) // line break: we use the other arc generator that has been built only for that
var posC = outerArc.centroid(d); // Label position = almost the same as posB
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2 // we need the angle to see if the X position will be at the extreme right or extreme left
posC[0] = radius * 0.95 * (midangle < Math.PI ? 1 : -1); // multiply by 1 or -1 to put it on the right or on the left
return [posA, posB, posC]
})
// Add the polylines between chart and labels:
svg
.selectAll('allLabels')
.data(data_ready)
.enter()
.append('text')
.text( function(d) { return d.data.facet} )
.attr('transform', function(d) {
var pos = outerArc.centroid(d);
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
pos[0] = radius * 0.99 * (midangle < Math.PI ? 1 : -1);
return 'translate(' + pos + ')';
})
.style('text-anchor', function(d) {
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
return (midangle < Math.PI ? 'start' : 'end')
})
</script>
Ok, the issues here is that you've completely missed how data_ready is structured after converting the JSON response. You might want to add console.log(data_ready) just after you set data_ready and inspect it in the console for better understanding of the following fixes.
First a color fix:
.attr('fill', function(d){ return(color(d.data.value.facet)) })
Then a data fix:
.value(function(d) {return d.value.count; })
And lastly a label fix:
.text( function(d) { console.log(d.data.key) ; return d.data.value.facet } )
Your script should look like this:
// set the dimensions and margins of the graph
var width = 450
height = 450
margin = 40
// The radius of the pieplot is half the width or half the height (smallest one). I subtract a bit of margin.
var radius = Math.min(width, height) / 2 - margin
// append the svg object to the div called 'my_dataviz'
var svg = d3.select("#chart")
.append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
d3.json("/data/all-facet-digitized.json", function(data) {
// set the color scale
var color = d3.scaleOrdinal()
.domain(["true","false"])
.range(d3.schemeDark2);
// Compute the position of each group on the pie:
var pie = d3.pie()
.sort(null) // Do not sort group by size
.value(function(d) {return d.value.count; })
var data_ready = pie(d3.entries(data))
// The arc generator
var arc = d3.arc()
.innerRadius(radius * 0.5) // This is the size of the donut hole
.outerRadius(radius * 0.8)
// Another arc that won't be drawn. Just for labels positioning
var outerArc = d3.arc()
.innerRadius(radius * 0.9)
.outerRadius(radius * 0.9)
// Build the pie chart: Basically, each part of the pie is a path that we build using the arc function.
svg
.selectAll('allSlices')
.data(data_ready)
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function(d){ return(color(d.data.value.facet)) })
.attr("stroke", "white")
.style("stroke-width", "2px")
.style("opacity", 0.7)
// Add the polylines between chart and labels:
svg
.selectAll('allPolylines')
.data(data_ready)
.enter()
.append('polyline')
.attr("stroke", "black")
.style("fill", "none")
.attr("stroke-width", 1)
.attr('points', function(d) {
var posA = arc.centroid(d) // line insertion in the slice
var posB = outerArc.centroid(d) // line break: we use the other arc generator that has been built only for that
var posC = outerArc.centroid(d); // Label position = almost the same as posB
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2 // we need the angle to see if the X position will be at the extreme right or extreme left
posC[0] = radius * 0.95 * (midangle < Math.PI ? 1 : -1); // multiply by 1 or -1 to put it on the right or on the left
return [posA, posB, posC]
})
// Add the polylines between chart and labels:
svg
.selectAll('allLabels')
.data(data_ready)
.enter()
.append('text')
.text( function(d) { console.log(d.data.key) ; return d.data.value.facet } )
.attr('transform', function(d) {
var pos = outerArc.centroid(d);
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
pos[0] = radius * 0.99 * (midangle < Math.PI ? 1 : -1);
return 'translate(' + pos + ')';
})
.style('text-anchor', function(d) {
var midangle = d.startAngle + (d.endAngle - d.startAngle) / 2
return (midangle < Math.PI ? 'start' : 'end')
})
})
I want to develop "drill down" "pie chart" using "D3.JS". I found the below sample, and perfect to me to use.
D3 Js sample drill down pie chart
The above sample is perfect fit for me.
Additionally from the sample drill down pie chart, I want to place TEXT LABEL in each section of pie chart divided.
I followed many samples,
Sample 1 - pie chart with section text label
Sample 2 - JSFiddle - pie chart with section text label
Based on the above samples for placing text label in pie chart sections, I followed the below code, I tried adding sample "var dataSet", "var arcs = svg.selectAll("g.slice")" code.
But, when I execute the program, it doesn't display any text label in centre of each section in pie chart.
Could someone guide me to fix this please?
<!doctype html>
<html>
<head>
<head>
<meta charset="utf-8">
<title>Drill down pie chart test</title>
<script type="text/javascript" src="http://d3js.org/d3.v2.min.js?2.9.6"></script>
<style type="text/css">
body {
text-align: center;
padding: 50px;
font-family: "Helvetica Neue",Arial,Sans-serif;
font-weight: 200;
color: #333;
}
.header {
font-size: 20px;
}
.sector {
cursor: pointer;
}
.slice text {
font-size: 16pt;
font-family: Arial;
}
</style>
</head>
<body>
<script type="text/javascript">
// Globals
var width = 500,
height = 400,
margin = 50,
radius = Math.min(width - margin, height - margin) / 2,
// Pie layout will use the "val" property of each data object entry
pieChart = d3.layout.pie().sort(null).value(function(d){return d.val;}),
arc = d3.svg.arc().outerRadius(radius),
MAX_SECTORS = 15, // Less than 20 please
colors = d3.scale.category20();
var dataSet = [
{"legendLabel":"One", "magnitude":20},
{"legendLabel":"Two", "magnitude":40},
{"legendLabel":"Three", "magnitude":50},
{"legendLabel":"Four", "magnitude":16},
{"legendLabel":"Five", "magnitude":50},
{"legendLabel":"Six", "magnitude":8},
{"legendLabel":"Seven", "magnitude":30}];
//mydata = {"Medical", "Agriculture", "Security"};
var st = {};
st.data = [{"label":"less than a week","value":169,"pos":0},{"label":"1 week - 30 days","value":1,"pos":1},{"label":"30 - 90 days","value":22,"pos":2},{"label":"90 - 180 days","value":35,"pos":3},{"label":"180 days - 1 year","value":47,"pos":4},{"label":"more than 1 year","value":783,"pos":5}] ;
// Synthetic data generation ------------------------------------------------
var data = [];
var numSectors = 8; //Math.ceil(Math.random()*MAX_SECTORS);
for(i = -1; i++ < numSectors; ) {
var children = [];
var numChildSectors = Math.ceil(Math.random()*MAX_SECTORS);
var color = colors(i);
for( j=-1; j++ < numChildSectors; ){
// Add children categories with shades of the parent color
children.push(
{ cat: "cat"+((i+1)*100+j),
val: Math.random(),
color: d3.rgb(color).darker(1/(j+1))
});
}
data.push({
cat: "cat"+i,
val: Math.random(),
color: color,
children: children});
}
// --------------------------------------------------------------------------
// SVG elements init
var svg = d3.select("body").append("svg").data([dataSet]).attr("width", width).attr("height", height),
defs = svg.append("svg:defs"),
// .data(pieChart)
// Declare a main gradient with the dimensions for all gradient entries to refer
mainGrad = defs.append("svg:radialGradient")
.attr("gradientUnits", "userSpaceOnUse")
.attr("cx", 0).attr("cy", 0).attr("r", radius).attr("fx", 0).attr("fy", 0)
.attr("id", "master"),
// The pie sectors container
arcGroup = svg.append("svg:g")
.attr("class", "arcGroup")
.attr("filter", "url(#shadow)")
.attr("transform", "translate(" + (width / 2) + "," + (height / 2) + ")"),
// Header text
header = svg.append("text").text("Biotechnology")
.attr("transform", "translate(10, 20)").attr("class", "header");
//svg.append("text").attr("text-anchor", "middle").text("$" + "sample"),
//svg.append("text").text("sample").attr("text-anchor", "middle")
/*svg.append("text")
.attr("transform", "translate(" + arcGroup.centroid(d) + ")")
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text("sample");
*/
// Declare shadow filter
var shadow = defs.append("filter").attr("id", "shadow")
.attr("filterUnits", "userSpaceOnUse")
.attr("x", -1*(width / 2)).attr("y", -1*(height / 2))
.attr("width", width).attr("height", height);
shadow.append("feGaussianBlur")
.attr("in", "SourceAlpha")
.attr("stdDeviation", "4")
.attr("result", "blur");
shadow.append("feOffset")
.attr("in", "blur")
.attr("dx", "4").attr("dy", "4")
.attr("result", "offsetBlur");
shadow.append("feBlend")
.attr("in", "SourceGraphic")
.attr("in2", "offsetBlur")
.attr("mode", "normal");
/* var arcs = svg.selectAll("g.slice")
arcs.append("text")
.attr("transform", function(d) { return "translate(" + arc.centroid(d) + ")"; })
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(function(d) { return d.value; });
*/
// Redraw the graph given a certain level of data
function updateGraph(cat){
var currData = data;
// Simple header text
if(cat != undefined){
currData = findChildenByCat(cat);
d3.select(".header").text("Biotechnology → "+cat);
} else {
d3.select(".header").text("Biotechnology");
}
// Create a gradient for each entry (each entry identified by its unique category)
var gradients = defs.selectAll(".gradient").data(currData, function(d){return d.cat;});
gradients.enter().append("svg:radialGradient")
.attr("id", function(d, i) { return "gradient" + d.cat; })
.attr("class", "gradient")
.attr("xlink:href", "#master");
gradients.append("svg:stop").attr("offset", "0%").attr("stop-color", getColor );
gradients.append("svg:stop").attr("offset", "90%").attr("stop-color", getColor );
gradients.append("svg:stop").attr("offset", "100%").attr("stop-color", getDarkerColor );
/*var arcs = defs.selectAll("g.slice").data(pie).enter().append("svg:g").attr("class","slice");
arcs.append("svg:text").attr("transform", function(d){
d.innerRadius = 0;
d.outerRadius = r;
return "translate(" + arc.centroid(d) + ")";}).attr("text-anchor", "middle").text( function(d, i) {
return (data[i].value / tot ) * 100 > 10 ? ((data[i].value / tot ) * 100).toFixed(1) + "%" : "";
}
).attr("fill","#fff")
.classed("slice-label",true);
*/
// Create a sector for each entry in the enter selection
var paths = arcGroup.selectAll("path")
.data(pieChart(currData), function(d) {return d.data.cat;} );
paths.enter().append("svg:path").attr("class", "sector");
// Each sector will refer to its gradient fill
paths.attr("fill", function(d, i) { return "url(#gradient"+d.data.cat+")"; })
.transition().duration(1000).attrTween("d", tweenIn).each("end", function(){
this._listenToEvents = true;
});
// Mouse interaction handling
paths.on("click", function(d){
if(this._listenToEvents){
// Reset inmediatelly
d3.select(this).attr("transform", "translate(0,0)")
// Change level on click if no transition has started
paths.each(function(){
this._listenToEvents = false;
});
updateGraph(d.data.children? d.data.cat : undefined);
}
})
.on("mouseover", function(d){
// Mouseover effect if no transition has started
if(this._listenToEvents){
// Calculate angle bisector
var ang = d.startAngle + (d.endAngle - d.startAngle)/2;
// Transformate to SVG space
ang = (ang - (Math.PI / 2) ) * -1;
// Calculate a 10% radius displacement
var x = Math.cos(ang) * radius * 0.1;
var y = Math.sin(ang) * radius * -0.1;
d3.select(this).transition()
.duration(250).attr("transform", "translate("+x+","+y+")");
}
})
.on("mouseout", function(d){
// Mouseout effect if no transition has started
if(this._listenToEvents){
d3.select(this).transition()
.duration(150).attr("transform", "translate(0,0)");
}
});
// Collapse sectors for the exit selection
paths.exit().transition()
.duration(1000)
.attrTween("d", tweenOut).remove();
// NEWLY ADDED START
// Select all <g> elements with class slice (there aren't any yet)
var arcs = svg.selectAll("g.slice")
// Associate the generated pie data (an array of arcs, each having startAngle,
// endAngle and value properties)
.data(pie)
// This will create <g> elements for every "extra" data element that should be associated
// with a selection. The result is creating a <g> for every object in the data array
.enter()
// Create a group to hold each slice (we will have a <path> and a <text>
// element associated with each slice)
.append("svg:g")
.attr("class", "slice"); //allow us to style things in the slices (like text)
arcs.append("svg:path")
//set the color for each slice to be chosen from the color function defined above
.attr("fill", function(d, i) { return color(i); } )
//this creates the actual SVG path using the associated data (pie) with the arc drawing function
.attr("d", arc);
// Add a legendLabel to each arc slice...
arcs.append("svg:text")
.attr("transform", function(d) { //set the label's origin to the center of the arc
//we have to make sure to set these before calling arc.centroid
d.outerRadius = outerRadius + 50; // Set Outer Coordinate
d.innerRadius = outerRadius + 45; // Set Inner Coordinate
return "translate(" + arc.centroid(d) + ")";
})
.attr("text-anchor", "middle") //center the text on it's origin
.style("fill", "Purple")
.style("font", "bold 12px Arial")
<!-- .text(function(d, i) { return dataSet[i].legendLabel; }); //get the label from our original dat -->
.text(function(d, i) { return "Test"; }); //get the label from our original dat
// Add a magnitude value to the larger arcs, translated to the arc centroid and rotated.
arcs.filter(function(d) { return d.endAngle - d.startAngle > .2; }).append("svg:text")
.attr("dy", ".35em")
.attr("text-anchor", "middle")
//.attr("transform", function(d) { return "translate(" + arc.centroid(d) + ")rotate(" + angle(d) + ")"; })
.attr("transform", function(d) { //set the label's origin to the center of the arc
//we have to make sure to set these before calling arc.centroid
d.outerRadius = outerRadius; // Set Outer Coordinate
d.innerRadius = outerRadius/2; // Set Inner Coordinate
return "translate(" + arc.centroid(d) + ")rotate(" + angle(d) + ")";
})
.style("fill", "White")
.style("font", "bold 12px Arial")
.text(function(d) { return d.data.magnitude; });
function angle(d) {
var a = (d.startAngle + d.endAngle) * 90 / Math.PI - 90;
return a > 90 ? a - 180 : a;
}
// END
}
// "Fold" pie sectors by tweening its current start/end angles
// into 2*PI
function tweenOut(data) {
data.startAngle = data.endAngle = (2 * Math.PI);
var interpolation = d3.interpolate(this._current, data);
this._current = interpolation(0);
return function(t) {
return arc(interpolation(t));
};
}
// "Unfold" pie sectors by tweening its start/end angles
// from 0 into their final calculated values
function tweenIn(data) {
var interpolation = d3.interpolate({startAngle: 0, endAngle: 0}, data);
this._current = interpolation(0);
return function(t) {
return arc(interpolation(t));
};
}
// Helper function to extract color from data object
function getColor(data, index){
return data.color;
}
// Helper function to extract a darker version of the color
function getDarkerColor(data, index){
return d3.rgb(getColor(data, index)).darker();
}
function findChildenByCat(cat){
for(i=-1; i++ < data.length - 1; ){
if(data[i].cat == cat){
return data[i].children;
}
}
return data;
}
//.text(function(d, i) { return categorydata[i].label; });
// Start by updating graph at root level
updateGraph();
</script>
<!-- <p>Drill down pie chart test by Marc Baiges Camprubí (marcbc#gmail.com) in D3.js -->
</body>
</html>
Instead of doing this:
var arcs = svg.selectAll("g.slice")
do this
var arcs = arcGroup.selectAll("g.slice")
reason so that the text label and the path of the pie all are in same group.
Give proper inner and outer radius for placing the labels in the center (so that the centroid is calculated on basis of the new inner outer radius of the arc)
arcs.append("svg:text")
.attr("transform", function(d) { //set the label's origin to the center of the arc
//we have to make sure to set these before calling arc.centroid
d.outerRadius = radius - 20; // Set Outer Coordinate
d.innerRadius = radius - 100; // Set Inner Coordinate
return "translate(" + arc.centroid(d) + ")";
})
Next give proper data in the text:
.text(function(d, i) { return "Test"; }); //get the label from our original data
do this
.text(function(d, i) { return d.data.cat; }); //get the label from our original data
working code here
This is the code I use for calling same js function in two blocks (in two div tag). The answer for the second tag (div id="frame4") also prints inside the first one (div id="frame3"). I want to print them separately. How can I do that?
<div id="frame3">
<! ----pieChart ----- !>
<h5><i>Code Coverage</i></h5>
<div id="pieChart"></div>
<script type="text/javascript">
dsPieChart(<%=coverage %>);
</script>
</div>
<!test_density !>
<div id="frame3">
<div id="pieChart"></div>
<script type="text/javascript">
dsPieChart(<%=density %>);
</script>
</div>
code for the function
function dsPieChart(x){
var formatAsPercentage = d3.format("%") ;
var dataset = [
{category: "", measure:x },
{category: "", measure:(100-x)},
]
;
var width = 100,
height = 100,
outerRadius = Math.min(width, height) / 2,
innerRadius = outerRadius * .9,
// for animation
innerRadiusFinal = outerRadius * .8,
innerRadiusFinal3 = outerRadius* .7,
color = d3.scale.category20b() //builtin range of colors
;
var vis = d3.select("#pieChart")
.append("svg:svg") //create the SVG element inside the <body>
.data([dataset]) //associate our data with the document
.attr("width", width) //set the width and height of our visualization (these will be attributes of the <svg> tag
.attr("height", height)
.append("svg:g") //make a group to hold our pie chart
.attr("transform", "translate(" + outerRadius + "," + outerRadius + ")") //move the center of the pie chart from 0, 0 to radius, radius
;
var arc = d3.svg.arc() //this will create <path> elements for us using arc data
.outerRadius(outerRadius).innerRadius(innerRadius);
// for animation
var arcFinal = d3.svg.arc().innerRadius(innerRadiusFinal).outerRadius(outerRadius);
var arcFinal3 = d3.svg.arc().innerRadius(innerRadiusFinal3).outerRadius(outerRadius);
var pie = d3.layout.pie() //this will create arc data for us given a list of values
.value(function(d) { return d.measure; }); //we must tell it out to access the value of each element in our data array
var arcs = vis.selectAll("g.slice") //this selects all <g> elements with class slice (there aren't any yet)
.data(pie) //associate the generated pie data (an array of arcs, each having startAngle, endAngle and value properties)
.enter() //this will create <g> elements for every "extra" data element that should be associated with a selection. The result is creating a <g> for every object in the data array
.append("svg:g") //create a group to hold each slice (we will have a <path> and a <text> element associated with each slice)
.attr("class", "slice") //allow us to style things in the slices (like text)
.on("mouseover", mouseover)
.on("mouseout", mouseout)
.on("click", up)
;
arcs.append("svg:path")
.attr("fill", function(d, i) { return color(i); } ) //set the color for each slice to be chosen from the color function defined above
.attr("d", arc) //this creates the actual SVG path using the associated data (pie) with the arc drawing function
.append("svg:title") //mouseover title showing the figures
// .text(function(d) { return d.data.category + ": " + d.data.measure ; });
.text(function(d) { return d.data.measure ; });
d3.selectAll("g.slice").selectAll("path").transition()
.duration(750)
.delay(10)
.attr("d", arcFinal )
;
// Add a label to the larger arcs, translated to the arc centroid and rotated.
arcs.filter(function(d) { return d.endAngle - d.startAngle > .2; })
.append("svg:text")
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.attr("transform", function(d) { return "translate(" + arcFinal.centroid(d) + ")rotate(" + angle(d) + ")"; })
.text(function(d) { return d.data.category; })
;
// Computes the label angle of an arc, converting from radians to degrees.
function angle(d) {
var a = (d.startAngle + d.endAngle) * 90 / Math.PI - 90;
return a > 90 ? a - 180 : a;
}
// Pie chart title
vis.append("svg:text")
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(x +"%")
.attr("class","title")
;
function mouseover() {
d3.select(this).select("path").transition()
.duration(750)
.attr("d", arcFinal3)
;
}
function mouseout() {
d3.select(this).select("path").transition()
.duration(750)
//.attr("stroke","blue")
//.attr("stroke-width", 1.5)
.attr("d", arcFinal)
;
}
function up(d, i) {
/* update bar chart when user selects piece of the pie chart */
//updateBarChart(dataset[i].category);
updateBarChart(d.data.category, color(i));
updateLineChart(d.data.category, color(i));
}
}
Change function to pass second parameter for element ID.
function dsPieChart(x, selectorId){
Change the hard code selector:
var vis = d3.select("#pieChart");
To
var vis = d3.select("#" + selectorId);
Then when you call the function also identify the id selector in second paramater. Note that element ID's must be unique in a page by definition:
<div id="pieChart-1"></div>
<script type="text/javascript">
dsPieChart(<%=coverage %>, 'pieChart-1');
</script>
</div>
<div id="pieChart-2"></div>
<script type="text/javascript">
dsPieChart(<%=density %>, 'pieChart-2');
</script>
</div>
After playing a while with d3.js and looking at a lot of examples, I was able to draw multiple arcs. Each one starting and ending at an specific degree and and given radius.
var dataset = {
"2":[{"degree1":0, "degree2":1.5707963267949,
"label":"Sample Text Test"},
{"degree1":1.5707963267949, "degree2":3.1415926535898,
"label":"Lorem ipsum sample text"},
{"degree1":3.1415926535898, "degree2":4.7123889803847,
"label":"Sample Text Text"},
{"degree1":4.7123889803847, "degree2":6.2831853071796,
"label":"Lorem ipsum"}],
"1":[{"degree1":0, "degree2":3.1415926535898,
"label":"Sample"},
{"degree1":3.1415926535898, "degree2":6.2831853071796,
"label":"Text"}],
"0":[{"degree1":0, "degree2":6.2831853071796,
"label":""}]
},
width = 450,
height = 450,
radius = 75;
// Helper methods
var innerRadius = function(d, i, j) {
return 1 + radius * j;
};
var outerRadius = function(d, i, j) {
return radius * (j + 1);
};
var startAngle = function(d, i, j) {
return d.data.degree1;
};
var endAngle = function(d, i, j) {
return d.data.degree2;
};
var pie = d3.layout.pie()
.sort(null);
var arc = d3.svg.arc()
.innerRadius(innerRadius)
.outerRadius(outerRadius)
.startAngle(startAngle)
.endAngle(endAngle);
var svg = d3.select('body').append('svg')
.attr('width', width)
.attr('height', height)
.append('g')
.attr('transform', 'translate(' + (width >> 1) + ',' + (height >> 1) + ')');
var level = svg.selectAll('g')
.data(function(d) {
return d3.values(dataset);
})
.enter()
.append('g');
var entry = level.selectAll('g')
.data(function(d, i) {
return pie(d);
})
.enter()
.append('g');
entry.append('path')
.attr('fill', '#aaa')
.attr('d', arc)
.attr('id', function(d, i, j) {
return 'arc' + i + '-' + j;
});
var label = entry.append('text')
.style('font-size', '20px')
.attr('dx', function(d, i, j) {
return Math.round((d.data.degree2 - d.data.degree1) * 180 / Math.PI);
})
.attr('dy', function(d, i, j) {
return ((radius * (j + 1)) - (1 + radius * j)) >> 1;
});
label.append('textPath')
.attr('xlink:href', function(d, i, j) {
return '#arc' + i + '-' + j;
})
.style('fill', '#000')
.text(function(d) {
return d.data.label;
});
See http://jsfiddle.net/3FP6P/2/ :
But some problem still exists:
How to center (horizonal und vertical) an text along an textpath of an any length inside an arc described by innerRadius, outerRadius, startAngle and endAngle?
The text occurs sometimes bold, sometimes not. Why?
The character spacing does not appear to be the same as if it is written inside a . Some letters stick more together as other ones. Why?
The letters are not located directly on the path. Some seem to have a little slip up or down. Why?
Vertical alignment
You can use another arc with radius (innerRadius + outerRadius) / 2 and use it as the textPath for the labels.
Note that even if you set the innerRadius == outerRadius, D3 will draw an path which moves clockwise and then anti-clockwise to doubles over itself. This becomes important while trying to figure out the horizontal centre of the path: it is at the 25% and 75% points while 0% and 50% points lie on the two tips of the arc.
Horizontal alignment
Use text-anchor: middle on the text element and set startOffset to 25% (or 75%) on the textPath.
Demo.
This is a more robust way than calculating the dx and dy by hand.
You should try out Lars's suggestions to further improve the quality and centring of the text, e.g. you might want to set text-rendering to optimizeLegibility and play with the baseline a bit.
Issues 2-4 are because of the font rendering. In my browser, the spacing and character size etc is consistent. You can try playing around with the text-rendering attribute to improve things.
To get the text centred, you will need to set the alignment-baseline and/or dominant-baseline attributes.
If this still doesn't give you the results you're looking for, try decreasing the font size. This may help because a slight rotation of a character will be less visible.