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I have successfully build my initial bar chart. Now I want to add more bars to that existing chart using transitions to have a nice user experience.

Here's my code:

var data = [23, 85, 67, 38, 70]; //dummy, normally much more
labellist = ['label1','label2','label3','label4','label5'];

var w = 815,
    h = 500,
    labelpad = 165,
    x = d3.scale.linear().domain([0, 100]).range([0, w]),
    y = d3.scale.ordinal().domain(d3.range(data.length)).rangeBands([0, h], .2);

mySvg = d3.select("#chart")
  .append("svg");

vis = mySvg.attr("width", w + 40)
    .attr("height", h + 20)
    .append("svg:g")
    .attr("transform", "translate(20,0)");

bars = vis.selectAll("g.bar")
    .data(data)
    .enter().append("svg:g")
    .attr("class", "bar")
    .attr("transform", function(d, i) { return "translate(" + labelpad + "," + y(i) + ")"; })


bars.append("svg:rect")

    .transition()
    .duration(500)
    .attr("width", x)
    .attr("height", y.rangeBand())
    ;



var rules = vis.selectAll("g.rule")
    .data(x.ticks(10))
  .enter().append("svg:g")
    .attr("class", "rule")
    .attr("transform", function(d) { return "translate(" + x(d) + ", 0)"; });

rules.append("svg:line")
    .attr("y1", h)
    .attr("y2", h + 6)
    .attr("x1", labelpad)
    .attr("x2", labelpad)
    .attr("stroke", "black");
rules.append("svg:line")
    .attr("y1", 0)
    .attr("y2", h)
    .attr("x1", labelpad)
    .attr("x2", labelpad)
    .attr("stroke", "white")
    .attr("stroke-opacity", .3);

How can I programmatically change the data to add and remove other bars and let the existing ones slide up/down?

I have successfully build my initial bar chart. Now I want to add more bars to that existing chart using transitions to have a nice user experience.

Here's my code:

var data = [23, 85, 67, 38, 70]; //dummy, normally much more
labellist = ['label1','label2','label3','label4','label5'];

var w = 815,
    h = 500,
    labelpad = 165,
    x = d3.scale.linear().domain([0, 100]).range([0, w]),
    y = d3.scale.ordinal().domain(d3.range(data.length)).rangeBands([0, h], .2);

mySvg = d3.select("#chart")
  .append("svg");

vis = mySvg.attr("width", w + 40)
    .attr("height", h + 20)
    .append("svg:g")
    .attr("transform", "translate(20,0)");

bars = vis.selectAll("g.bar")
    .data(data)
    .enter().append("svg:g")
    .attr("class", "bar")
    .attr("transform", function(d, i) { return "translate(" + labelpad + "," + y(i) + ")"; })


bars.append("svg:rect")

    .transition()
    .duration(500)
    .attr("width", x)
    .attr("height", y.rangeBand())
    ;



var rules = vis.selectAll("g.rule")
    .data(x.ticks(10))
  .enter().append("svg:g")
    .attr("class", "rule")
    .attr("transform", function(d) { return "translate(" + x(d) + ", 0)"; });

rules.append("svg:line")
    .attr("y1", h)
    .attr("y2", h + 6)
    .attr("x1", labelpad)
    .attr("x2", labelpad)
    .attr("stroke", "black");
rules.append("svg:line")
    .attr("y1", 0)
    .attr("y2", h)
    .attr("x1", labelpad)
    .attr("x2", labelpad)
    .attr("stroke", "white")
    .attr("stroke-opacity", .3);

How can I programmatically change the data to add and remove other bars and let the existing ones slide up/down?

  • javascript
  • charts
  • d3.js
  • updates
Share Improve this question edited Sep 12, 2012 at 12:50 John Conde 220k99 gold badges462 silver badges501 bronze badges asked Aug 28, 2012 at 18:08 HokaschaHokascha 2,2792 gold badges28 silver badges45 bronze badges
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1 Answer 1

Reset to default 6

You need to assign some form of key to the bars' data so d3 can identify ones that existed in the previous set. The default is index-based, and that may be what you want.

As far as the transitions go, you want to change your code to something like this:

bars = vis.selectAll("g.bar")
    .data(data);

bars.enter().append("svg:g")
    .attr("class", "bar")
    .append("svg:rect").

bars.transition().duration(500)
    .attr("transform", function(d, i) { 
         return "translate(" + labelpad + "," + y(i) + ")"; 
     })
    .selectAll("svg:rect")
    .attr("width", x)
    .attr("height", y.rangeBand())
;

bars.exit().transition().duration(500)
    .selectAll("svg:rect")
    .attr("height", 0)
    .remove();

The "enter()" function is best used to create the structure immediately. Then use the initial selection object (bars) to apply the new data to all elements.

You also probably want to remove any obsolete bars. Here I've resized them to 0 and then removed them, but you can tinker with it to get the effect you want.

本文标签： javascriptD3 How can I change data in an existing bar chartStack Overflow

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