.data() 处的 D3 新数据使 svg 重绘而不是更新节点位置
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【中文标题】.data() 处的 D3 新数据使 svg 重绘而不是更新节点位置【英文标题】:D3 new data at .data() makes svg to redraw instead of updating nodes position 【发布时间】:2021-04-24 20:19:57 【问题描述】:考虑到这个工作 example,数据更新使 svg 更新而不被重新绘制。使此行为的相关原始代码部分如下所述:
// DATA JOIN
link = link.data(firstLinks ? graph.links1 : graph.links2);
// DATA JOIN
node = node.data(graph.nodes);
simulation.force("link")
.links(firstLinks ? graph.links1 : graph.links2);
但是,如果节点和链接数据引用是新的,即使内容相同,svg 也会在每次更新时重新绘制。 相关更改的代码部分使其行为如下所述:
var new_graph_http_data = fetchNewData(); // unreferenced new data copy from graph
// DATA JOIN
link = link.data(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
// DATA JOIN
node = node.data(new_graph_http_data.nodes);
simulation.force("link")
.links(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
Here,在函数 update() 中,调用 update_local() 将使图形按预期工作。调用 update_http() 将使图形重新绘制。
// Local working vs fetch (clone)
function update()
/* Original working version */
// update_local();
/* Re-drawing version */
update_http();
;
update();
<!DOCTYPE html>
<html>
<meta charset="UTF-8">
<style>
/* Style Definitions */
button
position: absolute;
top: 1em;
left: 1em;
.node
stroke: white;
stroke-width: 2px;
.link
stroke: gray;
stroke-width: 2px;
</style>
<button type="button" id="switch-btn">Switch Links</button>
<svg ></svg>
<!--<script src="https://d3js.org/d3.v4.min.js"></script>-->
<script src="https://d3js.org/d3.v6.min.js"></script>
<script>
// graph data store
// Part of original blocks-data.json
var graph =
"nodes": [
"id": "0", "group": "1" ,
"id": "1", "group": "2" ,
"id": "2", "group": "2" ,
"id": "3", "group": "2" ,
"id": "4", "group": "2" ,
"id": "5", "group": "3" ,
"id": "6", "group": "3" ,
"id": "7", "group": "3" ,
"id": "8", "group": "3"
],
"links1": [
"source": "0", "target": "1",
"source": "0", "target": "2",
"source": "0", "target": "3",
"source": "0", "target": "4",
"source": "1", "target": "5",
"source": "2", "target": "6",
"source": "3", "target": "7",
"source": "4", "target": "8",
"source": "1", "target": "8",
"source": "2", "target": "5",
"source": "3", "target": "6",
"source": "4", "target": "7"
],
"links2": [
"source": "0", "target": "5",
"source": "0", "target": "6",
"source": "0", "target": "7",
"source": "0", "target": "8",
"source": "5", "target": "6",
"source": "5", "target": "8",
"source": "7", "target": "6",
"source": "7", "target": "8",
"source": "1", "target": "5",
"source": "2", "target": "6",
"source": "3", "target": "7",
"source": "4", "target": "8"
]
;
// state variable for current link set
var firstLinks = true;
// svg and sizing
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
// d3 color scheme
var color = d3.scaleOrdinal(d3.schemeCategory10);
// elements for data join
var link = svg.append("g").selectAll(".link"),
node = svg.append("g").selectAll(".node");
// simulation initialization
var simulation = d3.forceSimulation()
.force("link", d3.forceLink()
.id(function(d) return d.id; ))
.force("charge", d3.forceManyBody()
.strength(function(d) return -500;))
.force("center", d3.forceCenter(width / 2, height / 2));
// button event handling
d3.select("#switch-btn").on("click", function()
firstLinks = !firstLinks;
update();
);
// follow v4 general update pattern
function update_local()
// Update link set based on current state
// DATA JOIN
link = link.data(firstLinks ? graph.links1 : graph.links2);
// EXIT
// Remove old links
link.exit().remove();
// ENTER
// Create new links as needed.
link = link.enter().append("line")
.attr("class", "link")
.merge(link);
// DATA JOIN
node = node.data(graph.nodes);
// EXIT
node.exit().remove();
// ENTER
node = node.enter().append("circle")
.attr("class", "node")
.attr("r", 10)
.attr("fill", function(d) return color(d.group);)
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended)
)
.merge(node);
// Set nodes, links, and alpha target for simulation
simulation
.nodes(graph.nodes)
.on("tick", ticked);
simulation.force("link")
.links(firstLinks ? graph.links1 : graph.links2);
simulation.alphaTarget(0.3).restart();
// follow v4 general update pattern
function update_http()
var new_graph_http_data = fetchNewData();
// Update link set based on current state
// DATA JOIN
link = link.data(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
// EXIT
// Remove old links
link.exit().remove();
// ENTER
// Create new links as needed.
link = link.enter().append("line")
.attr("class", "link")
.merge(link);
// DATA JOIN
node = node.data(new_graph_http_data.nodes);
// EXIT
node.exit().remove();
// ENTER
node = node.enter().append("circle")
.attr("class", "node")
.attr("r", 10)
.attr("fill", function(d) return color(d.group);)
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended)
)
.merge(node);
// Set nodes, links, and alpha target for simulation
simulation
.nodes(new_graph_http_data.nodes)
.on("tick", ticked);
simulation.force("link")
.links(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
simulation.alphaTarget(0.3).restart();
// drag event handlers
function dragstarted(d)
if (!d3.event.active) simulation.alphaTarget(0.3).restart();
d.fx = d.x;
d.fy = d.y;
function dragged(d)
d.fx = d3.event.x;
d.fy = d3.event.y;
function dragended(d)
if (!d3.event.active) simulation.alphaTarget(0);
d.fx = null;
d.fy = null;
// tick event handler (nodes bound to container)
function ticked()
link
.attr("x1", function(d) return d.source.x; )
.attr("y1", function(d) return d.source.y; )
.attr("x2", function(d) return d.target.x; )
.attr("y2", function(d) return d.target.y; );
node
.attr("cx", function(d) return d.x; )
.attr("cy", function(d) return d.y; );
// Value copying function
function fetchNewData()
var idx, tempStr;
var obj =
"nodes": [],
"links1": [],
"links2": [],
;
for (idx in graph.nodes)
tempStr = JSON.stringify(graph.nodes[idx]);
tempStr = JSON.parse(tempStr);
obj.nodes.push(tempStr);
for (idx in graph.links1)
tempStr = JSON.stringify(graph.links1[idx]);
tempStr = JSON.parse(tempStr);
obj.links1.push(tempStr);
for (idx in graph.links2)
tempStr = JSON.stringify(graph.links2[idx]);
tempStr = JSON.parse(tempStr);
obj.links2.push(tempStr);
return obj;
</script>
</html>
在 Firefox 78.6.0esr 和 Chrome 86.0.4240.111 中使用 D3 v4.13.0 和 D3 v6.3.1 进行了测试。开发工具不会抛出任何错误。
谢谢。
【问题讨论】:
【参考方案1】:虽然您关注的是进入/更新/退出周期,但问题在于 d3-force:代表节点本身的对象存储自己的位置数据。
D3-force 修改每个节点的基准以包含位置属性。这些属性就是 tick 函数用来放置节点的属性:
node
.attr("cx", function(d) return d.x; )
.attr("cy", function(d) return d.y; );
)
除了d.x
和d.y
,还有d.vx
和d.vy
属性。如果节点不具有这些属性,则力将创建并分配它们。如果您删除所有节点并用没有x
,y
属性的新对象替换它们,则强制将创建并初始化这些属性,而不考虑先前的节点(毕竟,它们不再是模拟的一部分。从视觉上看,这将使它看起来像所有旧节点/链接都已退出并输入了新节点)。
如果通过(重新)加载节点将对象替换为新对象,并且新对象打算位于旧节点所在的位置,则可以转移节点的x
,y
,dx
, dy
属性,如果你想从旧节点到新对象,例如:
var old = simulation.nodes()
newGraph.nodes.forEach(function(node,i)
node.x = old[i].x;
node.y = old[i].y;
node.vx = old[i].vx;
node.vy = old[i].vy;
)
Update Fiddle
// Local working vs fetch (clone)
function update()
/* Original working version */
// update_local();
/* Re-drawing version */
update_http();
;
update();
<!DOCTYPE html>
<html>
<meta charset="UTF-8">
<style>
/* Style Definitions */
button
position: absolute;
top: 1em;
left: 1em;
.node
stroke: white;
stroke-width: 2px;
.link
stroke: gray;
stroke-width: 2px;
</style>
<button type="button" id="switch-btn">Switch Links</button>
<svg ></svg>
<!--<script src="https://d3js.org/d3.v4.min.js"></script>-->
<script src="https://d3js.org/d3.v6.min.js"></script>
<script>
// graph data store
// Part of original blocks-data.json
var graph =
"nodes": [
"id": "0", "group": "1" ,
"id": "1", "group": "2" ,
"id": "2", "group": "2" ,
"id": "3", "group": "2" ,
"id": "4", "group": "2" ,
"id": "5", "group": "3" ,
"id": "6", "group": "3" ,
"id": "7", "group": "3" ,
"id": "8", "group": "3"
],
"links1": [
"source": "0", "target": "1",
"source": "0", "target": "2",
"source": "0", "target": "3",
"source": "0", "target": "4",
"source": "1", "target": "5",
"source": "2", "target": "6",
"source": "3", "target": "7",
"source": "4", "target": "8",
"source": "1", "target": "8",
"source": "2", "target": "5",
"source": "3", "target": "6",
"source": "4", "target": "7"
],
"links2": [
"source": "0", "target": "5",
"source": "0", "target": "6",
"source": "0", "target": "7",
"source": "0", "target": "8",
"source": "5", "target": "6",
"source": "5", "target": "8",
"source": "7", "target": "6",
"source": "7", "target": "8",
"source": "1", "target": "5",
"source": "2", "target": "6",
"source": "3", "target": "7",
"source": "4", "target": "8"
]
;
// state variable for current link set
var firstLinks = true;
// svg and sizing
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
// d3 color scheme
var color = d3.scaleOrdinal(d3.schemeCategory10);
// elements for data join
var link = svg.append("g").selectAll(".link"),
node = svg.append("g").selectAll(".node");
// simulation initialization
var simulation = d3.forceSimulation()
.force("link", d3.forceLink()
.id(function(d) return d.id; ))
.force("charge", d3.forceManyBody()
.strength(function(d) return -500;))
.force("center", d3.forceCenter(width / 2, height / 2));
// button event handling
d3.select("#switch-btn").on("click", function()
firstLinks = !firstLinks;
update();
);
// follow v4 general update pattern
function update_local()
// Update link set based on current state
// DATA JOIN
link = link.data(firstLinks ? graph.links1 : graph.links2);
// EXIT
// Remove old links
link.exit().remove();
// ENTER
// Create new links as needed.
link = link.enter().append("line")
.attr("class", "link")
.merge(link);
// DATA JOIN
node = node.data(graph.nodes);
// EXIT
node.exit().remove();
// ENTER
node = node.enter().append("circle")
.attr("class", "node")
.attr("r", 10)
.attr("fill", function(d) return color(d.group);)
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended)
)
.merge(node);
// Set nodes, links, and alpha target for simulation
simulation
.nodes(graph.nodes)
.on("tick", ticked);
simulation.force("link")
.links(firstLinks ? graph.links1 : graph.links2);
simulation.alphaTarget(0.3).restart();
// follow v4 general update pattern
function update_http()
var new_graph_http_data = fetchNewData();
// Update link set based on current state
// DATA JOIN
link = link.data(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
// EXIT
// Remove old links
link.exit().remove();
// ENTER
// Create new links as needed.
link = link.enter().append("line")
.attr("class", "link")
.merge(link);
// DATA JOIN
node = node.data(new_graph_http_data.nodes);
// EXIT
node.exit().remove();
// ENTER
node = node.enter().append("circle")
.attr("class", "node")
.attr("r", 10)
.attr("fill", function(d) return color(d.group);)
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended)
)
.merge(node);
// Set nodes, links, and alpha target for simulation
simulation
.nodes(new_graph_http_data.nodes)
.on("tick", ticked);
simulation.force("link")
.links(firstLinks ? new_graph_http_data.links1 : new_graph_http_data.links2);
simulation.alphaTarget(0.3).restart();
// drag event handlers
function dragstarted(d)
if (!d3.event.active) simulation.alphaTarget(0.3).restart();
d.fx = d.x;
d.fy = d.y;
function dragged(d)
d.fx = d3.event.x;
d.fy = d3.event.y;
function dragended(d)
if (!d3.event.active) simulation.alphaTarget(0);
d.fx = null;
d.fy = null;
// tick event handler (nodes bound to container)
function ticked()
link
.attr("x1", function(d) return d.source.x; )
.attr("y1", function(d) return d.source.y; )
.attr("x2", function(d) return d.target.x; )
.attr("y2", function(d) return d.target.y; );
node
.attr("cx", function(d) return d.x; )
.attr("cy", function(d) return d.y; );
// Value copying function
function fetchNewData()
var idx, tempStr;
var obj =
"nodes": [],
"links1": [],
"links2": [],
;
for (idx in graph.nodes)
tempStr = JSON.stringify(graph.nodes[idx]);
tempStr = JSON.parse(tempStr);
obj.nodes.push(tempStr);
for (idx in graph.links1)
tempStr = JSON.stringify(graph.links1[idx]);
tempStr = JSON.parse(tempStr);
obj.links1.push(tempStr);
for (idx in graph.links2)
tempStr = JSON.stringify(graph.links2[idx]);
tempStr = JSON.parse(tempStr);
obj.links2.push(tempStr);
if(simulation.nodes().length)
var old = simulation.nodes()
obj.nodes.forEach(function(node,i)
node.x = old[i].x;
node.y = old[i].y;
node.vx = old[i].vx;
node.vy = old[i].vy;
)
return obj;
</script>
</html>
【讨论】:
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