title: How to set d3 stroke width
body: <p>At the moment the following draws two lines, but I can't seem to change the width:</p>
  
  <pre><code>var a = [23,50];
  for (b = 0; b &lt; a.length; b++) {
    var stripe = vis.selectAll("line.stripep")
      .data(connections.filter(function(d,i) { return i == a[b];  }))
      .enter().append("svg:line")
        .attr("class", "stripe")
        .attr("stroke", function(d) { return "#000000"; })
        .attr("stroke-linecap", 'round')
        .attr("stroke-width", 500)
        .attr("x1", function(d) { return x(d.station1.longitude); })
        .attr("y1", function(d) { return y(d.station1.latitude); })
        .attr("x2", function(d) { return x(d.station2.longitude); })
        .attr("y2", function(d) { return y(d.station2.latitude); })
  }
  </code></pre>
  
  <p>I want to set the width of the two black lines to 500.</p>
  
  <p>At the moment I am trying: </p>
  
  <pre><code>.attr("stroke-width", 500)
  </code></pre>
  
  <p>I have also tried:</p>
  
  <pre><code>.attr("stroke-width",  function(d) { return "500"; })
  </code></pre>
  
  <p>This also did not work. What is the correct way to do this?</p>