<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>D3: Adding values and elements to a chart</title>
<script type="text/javascript" src="../d3.js"></script>
<style type="text/css">
/* No style rules here yet */
</style>
</head>
<body>
<p>Click on this text to add a new data value to the chart!</p>
<script type="text/javascript">
//Width and height
var w = 600;
var h = 250;
var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,
11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];
var xScale = d3.scaleBand()
.domain(d3.range(dataset.length))
.rangeRound([0, w])
.paddingInner(0.05);
var yScale = d3.scaleLinear()
.domain([0, d3.max(dataset)])
.range([0, h]);
//Create SVG element
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
//Create bars
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d);
})
.attr("width", xScale.bandwidth())
.attr("height", function(d) {
return yScale(d);
})
.attr("fill", function(d) {
return "rgb(0, 0, " + Math.round(d * 10) + ")";
});
//Create labels
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) {
return d;
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return xScale(i) + xScale.bandwidth() / 2;
})
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
//On click, update with new data
d3.select("p")
.on("click", function() {
//Add one new value to dataset
var maxValue = 25;
var newNumber = Math.floor(Math.random() * maxValue); //New random integer (0-24)
dataset.push(newNumber); //Add new number to array
//Update scale domains
xScale.domain(d3.range(dataset.length)); //Recalibrate the x scale domain, given the new length of dataset
yScale.domain([0, d3.max(dataset)]); //Recalibrate the y scale domain, given the new max value in dataset
//Select…
var bars = svg.selectAll("rect") //Select all bars
.data(dataset); //Re-bind data to existing bars, return the 'update' selection
//'bars' is now the update selection
//Enter…
bars.enter() //References the enter selection (a subset of the update selection)
.append("rect") //Creates a new rect
.attr("x", w) //Sets the initial x position of the rect beyond the far right edge of the SVG
.attr("y", function(d) { //Sets the y value, based on the updated yScale
return h - yScale(d);
})
.attr("width", xScale.bandwidth()) //Sets the width value, based on the updated xScale
.attr("height", function(d) { //Sets the height value, based on the updated yScale
return yScale(d);
})
.attr("fill", function(d) { //Sets the fill value
return "rgb(0, 0, " + Math.round(d * 10) + ")";
})
.merge(bars) //Merges the enter selection with the update selection
.transition() //Initiate a transition on all elements in the update selection (all rects)
.duration(500)
.attr("x", function(d, i) { //Set new x position, based on the updated xScale
return xScale(i);
})
.attr("y", function(d) { //Set new y position, based on the updated yScale
return h - yScale(d);
})
.attr("width", xScale.bandwidth()) //Set new width value, based on the updated xScale
.attr("height", function(d) { //Set new height value, based on the updated yScale
return yScale(d);
});
//Update all labels
//
//Exercise: Modify this code to add a new label each time a new bar is added!
//
svg.selectAll("text")
.data(dataset)
.transition()
.duration(500)
.text(function(d) {
return d;
})
.attr("x", function(d, i) {
return xScale(i) + xScale.bandwidth() / 2;
})
.attr("y", function(d) {
return h - yScale(d) + 14;
});
});
</script>
</body>
</html>