title: D3: Removing Elements
body: <p>I have a bar chart that creates positive and negative bars.  I'm trying to remove the negative bars later on but for now, even after appending the bars, if I try to immediately remove the negative bars, they still appear.</p>
  
  <pre><code>var margin = {top: 30, right: 10, bottom: 10, left: 10},
      width = 750 - margin.left - margin.right,
      height = data.length * 20 //500 - margin.top - margin.bottom;
  
  var x = d3.scale.linear()
      .range([0, width*.85])
  
  //chart1.x =x
  //chart1.y = y
  
  var y = d3.scale.ordinal()
      .rangeRoundBands([0, height], 0);
  
  var xAxis = d3.svg.axis()
      .scale(x)
      .orient("top");
  
  var svg = d3.select("#barchart").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 + ")");
  
  //d3.tsv("data.tsv", type, function(error, data) {
    x.domain(d3.extent(data, function(d) { return +d.netdonations_over_population_to_gdppercap_percentage; })).nice();
    y.domain(data.map(function(d) { return d.name; }));
  
    bar = svg.selectAll(".bar")
        .data(data)
      .enter().append("rect")
        .attr("class", function(d) { return +d.netdonations_over_population_to_gdppercap_percentage &lt; 0 ? "bar negative" : "bar positive"; })
        .attr("x", function(d) { return x(Math.min(0, +d.netdonations_over_population_to_gdppercap_percentage)); })
        .attr("y", function(d) { return y(d.name); })
        .attr("width", function(d) { return Math.abs(x(+d.netdonations_over_population_to_gdppercap_percentage) - x(0)); })
        .attr("height", y.rangeBand()).style("stroke","white")
  
  bar.selectAll(".negative").data([]).exit().remove()
  </code></pre>
  
  <p>The remove statement is the last one.  The rest of the code:</p>
  
  <pre><code>svg.selectAll("text")
      .data(data)
    .enter().append("text").text(function(d) {
          return d;
     }).attr("y", function(d, i) {
          return y(d.name)+ y.rangeBand();
          //return i * (height / data.length)+30;
     }).attr("x", function(d) {
           return x(0) //x(Math.min(0, +d.netdonations_over_population_to_gdppercap_percentage));
     }).text(function(d) {
          //return y(d) + y.rangeBand() / 2;
          return d.name + " " + d.netdonations_over_population_to_gdppercap_percentage;
          }).style("font-size","14px").attr("dx", 3).attr("dy", "-0.45em")
  
  
    svg.append("g")
        .attr("class", "x axis")
        .call(xAxis);
  
    svg.append("g")
        .attr("class", "y axis")
      .append("line")
        .attr("x1", x(0))
        .attr("x2", x(0))
        .attr("y2", height);
  </code></pre>