function tufteAxis() {
  var scale, orient, data, q;

  var medianGap = 5, // gap width where the median of data is
      lineGap = 3;   // gap between lines marking 1st and 3rd quartiles

  var line = d3.svg.line();

  function axis(g) {
    var lineData = createLineData();

    var paths = g.selectAll("path").data(lineData);

    paths.enter().append("path");

    paths
      .transition().duration(1000)
      .attr("d", line);

    paths.exit().remove();
  }

  axis.scale = function(x) {
    if (!arguments.length) return scale;
    scale = x;
    return axis;
  };

  axis.orient = function(x) {
    if (!arguments.length) return orient;
    orient = x;
    return axis;
  };

  axis.data = function(x) {
    if (!arguments.length) return data;
    data = x;
    q = getQuartiles(data);
    return axis;
  };

  axis.medianGap = function(x) {
    if (!arguments.length) return medianGap;
    medianGap = x;
    return axis;
  };

  axis.lineGap = function(x) {
    if (!arguments.length) return lineGap;
    lineGap = x;
    return axis;
  };

  function getQuartiles(values) {
    values.sort(function(a, b) { return a - b; });
    var n = values.length - 1,
        q = {};
    [0, .25, .5, .75, 1].forEach(function(p) {
      var i = Math.round(n*p);
      q[p] = values[i];
    })
    return q;
  }

  function createLineData() {
    if (orient === "bottom") {
      return [
        [
          [scale(q[0]), lineGap],
          [scale(q[.25]), lineGap]
        ],
        [
          [scale(q[.25]), 0],
          [scale(q[.5]) - medianGap/2, 0]
        ],
        [
          [scale(q[.5]) + medianGap/2, 0],
          [scale(q[.75]), 0]
        ],
        [
          [scale(q[.75]), lineGap],
          [scale(q[1]), lineGap]
        ]
      ];
    }
    else if (orient === "left") {
      return [
        [
          [0, scale(q[0])],
          [0, scale(q[.25])]
        ],
        [
          [lineGap, scale(q[.25])],
          [lineGap, scale(q[.5]) + medianGap/2]
        ],
        [
          [lineGap, scale(q[.5]) - medianGap/2],
          [lineGap, scale(q[.75])]
        ],
        [
          [0, scale(q[.75])],
          [0, scale(q[1])]
        ]
      ];
    }
  }

  return axis;
}