var margin = 50, width = tributary.sw, height = tributary.sh;

var data = tributary.bus_perf;

var svg = d3.select("svg");

svg.attr("width",width)
   .attr("height",height)
   .selectAll("circle")
   .data(data)
   .enter()
   .append("circle");

var x_extent = d3.extent(data, function(d){ return d.collision_with_injury});
var x_scale = d3.scale.linear().range([margin,width-margin]).domain(x_extent);

var y_extent = d3.extent(data, function(d){ return d.dist_between_fail});
var y_scale = d3.scale.linear().range([height-margin, margin]).domain(y_extent);

d3.selectAll("circle")
.attr("cx", function(d){ return x_scale(d.collision_with_injury)})
.attr("cy", function(d){ return y_scale(d.dist_between_fail)});

d3.selectAll("circle")
.attr("r", 5);




var x_axis = d3.svg.axis().scale(x_scale);

svg.append("g")
   .attr("class","x axis")
   .attr("transform", "translate(0, "+ (height-margin) + ")" )
   .call(x_axis);
   

var y_axis = d3.svg.axis().scale(y_scale).orient("left");

svg.append("g")
   .attr("class","y axis")
   .attr("transform", "translate("+ margin + ", 0)" )
   .call(y_axis);