我正在使用以下链接中的代码：
https://www.d3-graph-gallery.com/graph/heatmap_tooltip.html
如果您下载此代码然后在浏览器中查看它，您会注意到鼠标悬停时的工具提示位置不再相对于热图中的单元格，而是显示为底部的长矩形。将此代码与我自己的代码集成后，我注意到了同样的情况。
我必须添加什么来强制工具提示出现在相对于热图单元格的位置？任何帮助将不胜感激。
【问题讨论】：
标签： html css d3.js mousehover
从该页面，您可能下载了刚刚左侧的红色框（即 HTML）“编辑我” 和它下方的框，即 JavaScript。如果单击 Download Code 按钮也会发生同样的情况，下载的文件仅包含 HTML 和 JavaScript。
所以，这就是你得到的：
// 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>如您所见，工具提示显示在 SVG 下方，正如您在问题中所描述的那样（如果单击 “整页”，您可以更好地看到它）。
因此，您在该示例中缺少第三个组件：CSS！
您可以按照自己的方式设置工具提示的样式，但这是 CSS 中用于定位工具提示的基本信息，给出了该链接中的代码：
.tooltip {
position: absolute;
}
这是相同的 sn-p，带有那个 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>如您所见，工具提示现在已正确定位。
最后，为了完整起见，这是该页面中工具提示的真实CSS（注意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;
}
}
}
【讨论】：