I am using the code found at the following link:
https://www.d3-graph-gallery.com/graph/heatmap_tooltip.html
If you download this code and then view it in a browser, you will notice the tooltip position on mouseover is no longer relative to the cell in the heat map but rather appears as a long rectangle towards the bottom. I noticed the same after integrating this code with my own.
What do I have to add to force the tooltip to appear in a position relative to the cell of the heat map? Any help would be greatly appreciated.
From that page, you probably downloaded the box just left to the "edit me" in red (which is the HTML) and the box below it, which is the JavaScript. The same happens if you click the Download Code button, the downloaded file contains only the HTML and the JavaScript.
So, this is what you get:
// set the dimensions and margins of the graph
var margin = {top: 30, right: 30, bottom: 30, left: 30},
width = 450 - margin.left - margin.right,
height = 450 - margin.top - margin.bottom;
// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
.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 + ")");
// Labels of row and columns
var myGroups = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J"]
var myVars = ["v1", "v2", "v3", "v4", "v5", "v6", "v7", "v8", "v9", "v10"]
// Build X scales and axis:
var x = d3.scaleBand()
.range([ 0, width ])
.domain(myGroups)
.padding(0.01);
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x))
// Build X scales and axis:
var y = d3.scaleBand()
.range([ height, 0 ])
.domain(myVars)
.padding(0.01);
svg.append("g")
.call(d3.axisLeft(y));
// Build color scale
var myColor = d3.scaleLinear()
.range(["white", "#69b3a2"])
.domain([1,100])
//Read the data
d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/heatmap_data.csv", function(data) {
// create a tooltip
var tooltip = d3.select("#my_dataviz")
.append("div")
.style("opacity", 0)
.attr("class", "tooltip")
.style("background-color", "white")
.style("border", "solid")
.style("border-width", "2px")
.style("border-radius", "5px")
.style("padding", "5px")
// Three function that change the tooltip when user hover / move / leave a cell
var mouseover = function(d) {
tooltip.style("opacity", 1)
}
var mousemove = function(d) {
tooltip
.html("The exact value of<br>this cell is: " + d.value)
.style("left", (d3.mouse(this)[0]+70) + "px")
.style("top", (d3.mouse(this)[1]) + "px")
}
var mouseleave = function(d) {
tooltip.style("opacity", 0)
}
// add the squares
svg.selectAll()
.data(data, function(d) {return d.group+':'+d.variable;})
.enter()
.append("rect")
.attr("x", function(d) { return x(d.group) })
.attr("y", function(d) { return y(d.variable) })
.attr("width", x.bandwidth() )
.attr("height", y.bandwidth() )
.style("fill", function(d) { return myColor(d.value)} )
.on("mouseover", mouseover)
.on("mousemove", mousemove)
.on("mouseleave", mouseleave)
})<!DOCTYPE html>
<meta charset="utf-8">
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>As you can see, the tooltip shows up below the SVG, just as you describe in your question (you can better see it if you click "full page").
Therefore, you're missing the third component in that example: the CSS!
You can style the tooltip the way you want, but this is the fundamental information in the CSS for positioning the tooltip, given the code in that link:
.tooltip {
position: absolute;
}
Here is the same snippet, with that CSS:
// set the dimensions and margins of the graph
var margin = {
top: 30,
right: 30,
bottom: 30,
left: 30
},
width = 450 - margin.left - margin.right,
height = 450 - margin.top - margin.bottom;
// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
.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 + ")");
// Labels of row and columns
var myGroups = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J"]
var myVars = ["v1", "v2", "v3", "v4", "v5", "v6", "v7", "v8", "v9", "v10"]
// Build X scales and axis:
var x = d3.scaleBand()
.range([0, width])
.domain(myGroups)
.padding(0.01);
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x))
// Build X scales and axis:
var y = d3.scaleBand()
.range([height, 0])
.domain(myVars)
.padding(0.01);
svg.append("g")
.call(d3.axisLeft(y));
// Build color scale
var myColor = d3.scaleLinear()
.range(["white", "#69b3a2"])
.domain([1, 100])
//Read the data
d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/heatmap_data.csv", function(data) {
// create a tooltip
var tooltip = d3.select("#my_dataviz")
.append("div")
.style("opacity", 0)
.attr("class", "tooltip")
.style("background-color", "white")
.style("border", "solid")
.style("border-width", "2px")
.style("border-radius", "5px")
.style("padding", "5px")
// Three function that change the tooltip when user hover / move / leave a cell
var mouseover = function(d) {
tooltip.style("opacity", 1)
}
var mousemove = function(d) {
tooltip
.html("The exact value of<br>this cell is: " + d.value)
.style("left", (d3.mouse(this)[0] + 70) + "px")
.style("top", (d3.mouse(this)[1]) + "px")
}
var mouseleave = function(d) {
tooltip.style("opacity", 0)
}
// add the squares
svg.selectAll()
.data(data, function(d) {
return d.group + ':' + d.variable;
})
.enter()
.append("rect")
.attr("x", function(d) {
return x(d.group)
})
.attr("y", function(d) {
return y(d.variable)
})
.attr("width", x.bandwidth())
.attr("height", y.bandwidth())
.style("fill", function(d) {
return myColor(d.value)
})
.on("mouseover", mouseover)
.on("mousemove", mousemove)
.on("mouseleave", mouseleave)
}).tooltip {
position: absolute;
}<!DOCTYPE html>
<meta charset="utf-8">
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>As you can see, the tooltip is correctly positioned now.
Finally, just for completeness, this is the real CSS of the tooltip in that page (pay attention to position):
.tooltip {
position: absolute;
z-index: $zindex-tooltip;
display: block;
margin: $tooltip-margin;
// Our parent element can be arbitrary since tooltips are by default inserted as a sibling of their target element.
// So reset our font and text properties to avoid inheriting weird values.
@include reset-text();
font-size: $tooltip-font-size;
// Allow breaking very long words so they don't overflow the tooltip's bounds
word-wrap: break-word;
opacity: 0;
&.show { opacity: $tooltip-opacity; }
.arrow {
position: absolute;
display: block;
width: $tooltip-arrow-width;
height: $tooltip-arrow-height;
&::before {
position: absolute;
content: "";
border-color: transparent;
border-style: solid;
}
}
}