d3.svg.axis = function() {

  var scale = d3.scale.linear(),

      orient = "bottom",

      tickMajorSize = 6,

      tickMinorSize = 6,

      tickEndSize = 6,

      tickPadding = 3,

      tickArguments_ = [10],

      tickFormat_,

      tickSubdivide = 0;

  function axis(selection) {

    selection.each(function(d, i, j) {

      var g = d3.select(this);

      // If selection is a transition, create subtransitions.

      var transition = selection.delay ? function(o) {

        var id = d3_transitionInheritId;

        try {

          d3_transitionInheritId = selection.id;

          return o.transition()

              .delay(selection[j][i].delay)

              .duration(selection[j][i].duration)

              .ease(selection.ease());

        } finally {

          d3_transitionInheritId = id;

        }

      } : Object;

      // Ticks.

      var ticks = scale.ticks.apply(scale, tickArguments_),

          tickFormat = tickFormat_ == null ? scale.tickFormat.apply(scale, tickArguments_) : tickFormat_;

      // Minor ticks.

      var subticks = d3_svg_axisSubdivide(scale, ticks, tickSubdivide),

          subtick = g.selectAll(".minor").data(subticks, String),

          subtickEnter = subtick.enter().insert("svg:line", "g").attr("class", "tick minor").style("opacity", 1e-6),

          subtickExit = transition(subtick.exit()).style("opacity", 1e-6).remove(),

          subtickUpdate = transition(subtick).style("opacity", 1);

      // Major ticks.

      var tick = g.selectAll("g").data(ticks, String),

          tickEnter = tick.enter().insert("svg:g", "path").style("opacity", 1e-6),

          tickExit = transition(tick.exit()).style("opacity", 1e-6).remove(),

          tickUpdate = transition(tick).style("opacity", 1),

          tickTransform;

      // Domain.

      var range = d3_scaleExtent(scale.range()),

          path = g.selectAll(".domain").data([0]),

          pathEnter = path.enter().append("svg:path").attr("class", "domain"),

          pathUpdate = transition(path);

      // Stash the new scale and grab the old scale.

      var scale0 = this.__chart__ || scale;

      this.__chart__ = scale.copy();

      tickEnter.append("svg:line").attr("class", "tick");

      tickEnter.append("svg:text");

      tickUpdate.select("text").text(tickFormat);

      switch (orient) {

        case "bottom": {

          tickTransform = d3_svg_axisX;

          subtickUpdate.attr("x2", 0).attr("y2", tickMinorSize);

          tickUpdate.select("line").attr("x2", 0).attr("y2", tickMajorSize);

          tickUpdate.select("text").attr("x", 0).attr("y", Math.max(tickMajorSize, 0) + tickPadding).attr("dy", ".71em").attr("text-anchor", "middle");

          pathUpdate.attr("d", "M" + range[0] + "," + tickEndSize + "V0H" + range[1] + "V" + tickEndSize);

          break;

        }

        case "top": {

          tickTransform = d3_svg_axisX;

          subtickUpdate.attr("x2", 0).attr("y2", -tickMinorSize);

          tickUpdate.select("line").attr("x2", 0).attr("y2", -tickMajorSize);

          tickUpdate.select("text").attr("x", 0).attr("y", -(Math.max(tickMajorSize, 0) + tickPadding)).attr("dy", "0em").attr("text-anchor", "middle");

          pathUpdate.attr("d", "M" + range[0] + "," + -tickEndSize + "V0H" + range[1] + "V" + -tickEndSize);

          break;

        }

        case "left": {

          tickTransform = d3_svg_axisY;

          subtickUpdate.attr("x2", -tickMinorSize).attr("y2", 0);

          tickUpdate.select("line").attr("x2", -tickMajorSize).attr("y2", 0);

          tickUpdate.select("text").attr("x", -(Math.max(tickMajorSize, 0) + tickPadding)).attr("y", 0).attr("dy", ".32em").attr("text-anchor", "end");

          pathUpdate.attr("d", "M" + -tickEndSize + "," + range[0] + "H0V" + range[1] + "H" + -tickEndSize);

          break;

        }

        case "right": {

          tickTransform = d3_svg_axisY;

          subtickUpdate.attr("x2", tickMinorSize).attr("y2", 0);

          tickUpdate.select("line").attr("x2", tickMajorSize).attr("y2", 0);

          tickUpdate.select("text").attr("x", Math.max(tickMajorSize, 0) + tickPadding).attr("y", 0).attr("dy", ".32em").attr("text-anchor", "start");

          pathUpdate.attr("d", "M" + tickEndSize + "," + range[0] + "H0V" + range[1] + "H" + tickEndSize);

          break;

        }

      }

      tickEnter.call(tickTransform, scale0);

      tickUpdate.call(tickTransform, scale);

      tickExit.call(tickTransform, scale);

      subtickEnter.call(tickTransform, scale0);

      subtickUpdate.call(tickTransform, scale);

      subtickExit.call(tickTransform, scale);

    });

  }

  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.ticks = function() {

    if (!arguments.length) return tickArguments_;

    tickArguments_ = arguments;

    return axis;

  };

  axis.tickFormat = function(x) {

    if (!arguments.length) return tickFormat_;

    tickFormat_ = x;

    return axis;

  };

  axis.tickSize = function(x, y, z) {

    if (!arguments.length) return tickMajorSize;

    var n = arguments.length - 1;

    tickMajorSize = +x;

    tickMinorSize = n > 1 ? +y : tickMajorSize;

    tickEndSize = n > 0 ? +arguments[n] : tickMajorSize;

    return axis;

  };

  axis.tickPadding = function(x) {

    if (!arguments.length) return tickPadding;

    tickPadding = +x;

    return axis;

  };

  axis.tickSubdivide = function(x) {

    if (!arguments.length) return tickSubdivide;

    tickSubdivide = +x;

    return axis;

  };

  return axis;

};

function d3_svg_axisX(selection, x) {

  selection.attr("transform", function(d) { return "translate(" + x(d) + ",0)"; });

}

function d3_svg_axisY(selection, y) {

  selection.attr("transform", function(d) { return "translate(0," + y(d) + ")"; });

}

function d3_svg_axisSubdivide(scale, ticks, m) {

  subticks = [];

  if (m && ticks.length > 1) {

    var extent = d3_scaleExtent(scale.domain()),

        subticks,

        i = -1,

        n = ticks.length,

        d = (ticks[1] - ticks[0]) / ++m,

        j,

        v;

    while (++i < n) {

      for (j = m; --j > 0;) {

        if ((v = +ticks[i] - j * d) >= extent[0]) {

          subticks.push(v);

        }

      }

    }

    for (--i, j = 0; ++j < m && (v = +ticks[i] + j * d) < extent[1];) {

      subticks.push(v);

    }

  }

  return subticks;

}