d3.js更新Visual.
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11-12-2019 - |
题
我有一个我与d3.js一起放的treemp。我通过getjson填充数据。它很棒。但是,我在setInterval方法中拥有此功能,并且它似乎似乎自身刷新。
var treemap = d3.layout.treemap()
.padding(4)
.size([w, h])
.value(function(d) { return d.size; });
var svg = d3.select("#chart").append("svg")
.style("position", "relative")
.style("width", w + "px")
.style("height", h + "px");
function redraw3(json) {
var cell = svg.data([json]).selectAll("g")
.data(treemap)
.enter().append("g")
.attr("class", "cell")
.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
cell.append("rect")
.attr("width", function(d) { return d.dx; })
.attr("height", function(d) { return d.dy; })
.style("fill", function(d) { return d.children ? color(d.data.name) : null; });
cell.append("text")
.attr("x", function(d) { return d.dx / 2; })
.attr("y", function(d) { return d.dy / 2; })
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(function(d) { return d.children ? null : d.data.name; });
}
setInterval(function() {
d3.json("http://localhost:8080/dev_tests/d3/examples/data/flare2.json", function(json) {
redraw3(json);
});
}, 3000);
.
我的问题具体,是为什么当我在JSON文件中更改数据时,它在Treemap稍后稍后显示出3秒钟?
提前谢谢。
解决方案
What's in the data? Because if the data array has the same length, the enter()
selection (which corresponds to previously unbound data) will have a length of zero. Mike Bostock wrote a great tutorial called Thinking with Joins, which I would recommend reading before you go any further.
The svg.data()
call seems redundant, and for clarity's sake I'd recommend doing this instead:
var leaves = treemap(json);
console.log("leaves:", leaves); // so you can see what's happening
// cell here is the bound selection, which has 3 parts
var cell = svg.selectAll("g")
.data(leaves);
// you might want to console.log(cell) here too so you can take a look
// 1. the entering selection is new stuff
var entering = cell.enter()
.append("g")
entering.append("rect")
// [update rectangles]
entering.append("text")
// [update text]
// 2. the exiting selection is old stuff
cell.exit().remove();
// 3. everything else is the "updating" selection
cell.select("rect")
// [update rectangles]
cell.select("text")
// [update text]
You can also encapsulate the updating of cells in a function and "call" it on both the entering and updating selections, so you don't have to write the same code twice:
function update() {
cell.select("rect")
// [update rectangles]
cell.select("text")
// [update text]
}
entering.append("rect");
entering.append("text");
entering.call(update);
cell.call(update);
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