Bivariate Line Graph using Nested element data

I'm only a few days into learning d3.js, and I am now trying to learn how to create graphs using nested data structures by recreating this graph http://bl.ocks.org/mbostock/3894205

enter image description here

... with a different dataset. I'm hoping someone can show me the proper way to do this.

view source/js-console of my script here: http://artfuladvection.com/project/NOAA/percentilesGraph/tempdifference.html
My data set compares temperatures from the last 24-hrs to the 24-hr hours prior
X-coordinates will not be the shared between the two line graphs. (hence why I am using nest)

This is the dataset for my graph... ie:

date,value,graph
2014-01-28 09:59:00,57.86,0
2014-01-28 09:33:00,56.83,0
2014-01-28 09:17:00,55.82,0
...    
2014-01-27 10:50:00,50.65,1
2014-01-27 10:39:00,49.65,1
2014-01-27 10:19:00,48.64,1

I've successfully created a nested data structure, ie:

My Object Preview

Now, I'm stuck on the final steps of displaying my data. I think it may have something to do with these 'NaN's showing up in my svg's path. For some reason, I think my x-axis domain might not be properly set. Is this significant?

<path class="line"    d="MNaN,125.9725400457666LNaN,128.91876430205951CNaN,131.86498855835242,NaN,137.75743707093827,NaN,143.59267734553782CNaN,149.42791762013735,NaN,155.20594965675062,NaN,163.90160183066365CNaN,172.59725400457668,NaN,184.21052631578948,NaN,189.6453089244851CNaN,195.08009153318076,NaN,194.33638443935922,NaN,193.96453089244847CNaN,193.59267734553768,NaN,193.59267734553768,NaN,202.14530892448505CNaN,210.69794050343245,NaN,227.80320366132722,NaN,231.06407322654462CNaN,234.32494279176203,NaN,223.74141876430207,NaN,2...739130434784CNaN,150.28604118993135,NaN,156.06407322654462,NaN,160.35469107551486CNaN,164.64530892448514,NaN,167.44851258581235,NaN,169.6796338672769CNaN,171.91075514874143,NaN,173.56979405034326,NaN,187.07093821510296CNaN,200.57208237986268,NaN,225.91533180778026,NaN,226.63043478260863CNaN,227.345537757437,NaN,203.43249427917615,NaN,194.45080091533177CNaN,185.46910755148735,NaN,191.41876430205946,NaN,197.3398169336384CNaN,203.26086956521735,NaN,209.1533180778032,NaN,212.0995423340961LNaN,215.045766590389">

Thanks.

Solution

Interestingly enough, the problem wasn't with the lines or the data objects, but with the domain's of my axis. I fixed this by adjusting my x.domain and y.domain. Final code:

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
font: 10px sans-serif;
}

.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}


.area.above { 
fill: rgb(252,141,89);
}

.area.below {
fill: rgb(145,207,96);
}

.line {
fill: none;
stroke: #000;
stroke-width: 1.5px;
}

body{margin:0px;}
rect {stroke:black;fill:white;}
circle {fill:steelblue;opacity:.5;}


</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>

var margin = {top: 20, right: 20, bottom: 30, left: 50},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;

var parseDate = d3.time.format("%Y-%m-%d %H:%M:%S").parse;  

var x = d3.time.scale()
.range([0, width]);

var y = d3.scale.linear()
.range([height, 0]);

var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom");

var yAxis = d3.svg.axis()
.scale(y)
.orient("left");

var color = d3.scale.category10();


var line = d3.svg.line()
.interpolate("basis")
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.value); });


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

var data;   
d3.csv("tempdifference.csv",function(csv) {

csv.forEach(function(d) {
d.date = parseDate(d.date);
});

data=d3.nest()
.key(function(d) {return d.graph;})
.entries(csv);
console.log(data);


x.domain(d3.extent(csv, function(d) { return d.date; }));
y.domain([
d3.min(data, function(c) { return d3.min(c.values, function(v) { return v.value; }); }),
d3.max(data, function(c) { return d3.max(c.values, function(v) { return v.value; }); })
]);



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

svg.append("g")
  .attr("class", "y axis")
  .call(yAxis)
.append("text")
  .attr("transform", "rotate(-90)")
  .attr("y", 6)
  .attr("dy", ".71em")
  .style("text-anchor", "end")
  .text("Temperature (°F)");      


var graph = svg.selectAll(".graph")
  .data(data)
.enter().append("g")
  .attr("class", "graph");

graph.append("path")
  .attr("class", "line")
  .attr("d", function(d) { return line(d.values); })


  console.log(graph);


console.log(svg);
});



</script>