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Last active August 29, 2015 14:04
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d3.js scatterplot and heat (density) chart
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README.md

d3.js example showing a scatterplot with 500-50,000 random points and its associated density heat chart

Raw
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title></title>
<style>
div#plots {
margin-bottom: 15px;
}
div#scatterplot, div#heatchart {
border: 1px solid #ccc;
margin-bottom: 10px;
}
div#scatterContainer, div#heatchartContainer {
float: left;
margin-left: 15px;
margin-bottom: 20px;
}
button {
margin-left: 15px;
margin-bottom: 15px;
}
circle {
fill: #09c;
}
select {
margin-left: 15px;
}
</style>
</head>
<body>
<select onchange="onNumPointsChange(event);">
<option value="500">500</option>
<option value="1500" selected="true">1500</option>
<option value="5000">5000</option>
<option value="15000">15,000</option>
<option value="25000">25,000</option>
<option value="50000">50,000</option>
</select> points
<button onclick="onRandomizeClick();">Randomize!</button>
<div id="plots">
<div id="scatterContainer">
<div id="scatterplot"></div>
<input type="checkbox" checked="true" onchange="onShowScatterplotChange(event);">show scatterplot</input>
</div>
<div id="heatchartContainer">
<div id="heatchart"></div>
</div>
</div>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
var numPoints = 1500,
size = 300,
numRows = 100,
numCols = 100,
showingScatter = true,
scatterDirty = false,
data = null,
cells = null,
color = d3.interpolateRgb("#fff", "#c09");
var getEmptyCells = function() {
var emptyCells = [];
for (var rowNum = 0; rowNum < numRows; rowNum++) {
emptyCells.push([]);
var row = emptyCells[emptyCells.length - 1];
for (var colNum = 0; colNum < numCols; colNum++) {
row.push({
row: rowNum,
col: colNum,
density: 0,
points: []
});
}
}
return emptyCells;
};
var clearCells = function() {
for (var rowNum = 0; rowNum < numRows; rowNum++) {
for (var colNum = 0; colNum < numCols; colNum++) {
cells[rowNum][colNum].density = 0;
cells[rowNum][colNum].points = [];
}
}
};
var randomizeData = function() {
data = [];
if (cells === null) {
cells = getEmptyCells();
}
else {
clearCells();
}
var x, y, col, row;
for (var i = 0; i < numPoints; i++) {
x = Math.random() * size;
y = Math.random() * size;
col = Math.min(Math.floor(x / size * numCols), numCols - 1);
row = Math.min(Math.floor(y / size * numRows), numRows - 1);
data.push({
x: x,
y: y,
col: col,
row: row,
cell: cells[row][col],
ind: i
});
cells[row][col].points.push(data[data.length - 1]);
}
};
var selectPoints = function(points) {
d3.selectAll(points).attr("r", 4).attr("stroke", "#f00").attr("stroke-width", 3);
for (var i = 0; i < points.length; i++) {
points[i].parentNode.appendChild(points[i]);
}
};
var deselectPoints = function(points) {
d3.selectAll(points).attr("r", 2).attr("stroke", "none");
};
var selectCell = function(cell) {
d3.select(cell).attr("stroke", "#f00").attr("stroke-width", 3);
cell.parentNode.parentNode.appendChild(cell.parentNode);
cell.parentNode.appendChild(cell);
};
var deselectCell = function(cell) {
d3.select(cell).attr("stroke", "#fff").attr("stroke-width", 1);
};
var onPointOver = function(point, data) {
selectPoints([point]);
var cell = d3.select("div#heatchart").select('[cell="r' + data.row + 'c' + data.col + '"]');
selectCell(cell.node());
};
var onPointOut = function(point, data) {
deselectPoints([point]);
var cell = d3.select("div#heatchart").select('[cell="r' + data.row + 'c' + data.col + '"]');
deselectCell(cell.node());
};
var createScatterplot = function() {
var scatterplot = d3.select("div#scatterplot").append("svg:svg").attr("width", size).attr("height", size);
scatterplot.selectAll("circle").data(data).enter().append("svg:circle").attr("cx", function(d, i) {
return d.x;
}).attr("cy", function(d, i) {
return d.y;
}).attr("r", 2).attr("ind", function(d) {
return d.ind;
}).on("mouseover", function(d) {
onPointOver(this, d);
}).on("mouseout", function(d) {
onPointOut(this, d);
});
};
var onCellOver = function(cell, data) {
selectCell(cell);
if (showingScatter) {
var pointEls = [];
for (var i = 0; i < data.points.length; i++) {
pointEls.push(d3.select("div#scatterplot").select('[ind="' + data.points[i].ind + '"]').node());
}
selectPoints(pointEls);
}
};
var onCellOut = function(cell, data) {
deselectCell(cell);
if (showingScatter) {
var pointEls = [];
for (var i = 0; i < data.points.length; i++) {
pointEls.push(d3.select("div#scatterplot").select('[ind="' + data.points[i].ind + '"]').node());
}
deselectPoints(pointEls);
}
};
var updateScatterplot = function() {
// select
var dots = d3.select("div#scatterplot").select("svg").selectAll("circle").data(data);
// enter
dots.enter().append("svg:circle").attr("cx", function(d, i) {
return d.x;
}).attr("cy", function(d, i) {
return d.y;
}).attr("r", 2).attr("ind", function(d) {
return d.ind;
}).on("mouseover", function(d) {
onPointOver(this, d);
}).on("mouseout", function(d) {
onPointOut(this, d);
});
// update
dots.attr("cx", function(d, i) {
return d.x;
}).attr("cy", function(d, i) {
return d.y;
}).attr("ind", function(d) {
return d.ind;
}).on("mouseover", function(d) {
onPointOver(this, d);
}).on("mouseout", function(d) {
onPointOut(this, d);
});
// exit
dots.exit().remove();
};
var createHeatchart = function() {
var min = 999;
var max = -999;
var l;
for (var rowNum = 0; rowNum < cells.length; rowNum++) {
for (var colNum = 0; colNum < numCols; colNum++) {
l = cells[rowNum][colNum].points.length;
if (l > max) {
max = l;
}
if (l < min) {
min = l;
}
}
}
var heatchart = d3.select("div#heatchart").append("svg:svg").attr("width", size).attr("height", size);
heatchart.selectAll("g").data(cells).enter().append("svg:g").selectAll("rect").data(function(d) {
return d;
}).enter().append("svg:rect").attr("x", function(d, i) {
return d.col * (size / numCols);
}).attr("y", function(d, i) {
return d.row * (size / numRows);
}).attr("width", size / numCols).attr("height", size / numRows).attr("fill", function(d, i) {
return color((d.points.length - min) / (max - min));
})
//.attr("stroke", "#fff")
.attr("cell", function(d) {
return "r" + d.row + "c" + d.col;
}).on("mouseover", function(d) {
onCellOver(this, d);
}).on("mouseout", function(d) {
onCellOut(this, d);
});
};
var updateHeatchart = function() {
var min = 999;
var max = -999;
var l;
for (var rowNum = 0; rowNum < cells.length; rowNum++) {
for (var colNum = 0; colNum < numCols; colNum++) {
l = cells[rowNum][colNum].points.length;
if (l > max) {
max = l;
}
if (l < min) {
min = l;
}
}
}
d3.select("div#heatchart").select("svg").selectAll("g").data(cells).selectAll("rect").data(function(d) {
return d;
}).attr("x", function(d, i) {
return d.col * (size / numCols);
}).attr("y", function(d, i) {
return d.row * (size / numRows);
}).attr("fill", function(d, i) {
return color((d.points.length - min) / (max - min));
}).attr("cell", function(d) {
return "r" + d.row + "c" + d.col;
}).on("mouseover", function(d) {
onCellOver(this, d);
}).on("mouseout", function(d) {
onCellOut(this, d);
});
};
var onRandomizeClick = function() {
randomizeData();
if (showingScatter) {
updateScatterplot();
}
else {
scatterDirty = true;
}
updateHeatchart();
};
var onNumPointsChange = function(event) {
numPoints = event.target.options[event.target.selectedIndex].value;
randomizeData();
if (showingScatter) {
updateScatterplot();
}
else {
scatterDirty = true;
}
updateHeatchart();
};
var onShowScatterplotChange = function(event) {
showingScatter = event.target.checked;
if (showingScatter) {
if (scatterDirty) {
updateScatterplot();
scatterDirty = false;
}
d3.select("div#scatterplot").select("svg").attr("visibility", "visible");
}
else {
d3.select("div#scatterplot").select("svg").attr("visibility", "hidden");
}
};
var init = function() {
randomizeData();
createScatterplot();
createHeatchart();
};
init();
</script>
</body>
</html>
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