Make a line chart in D3.js loading data from an array

Question

I'm trying to make a simple line graph in D3.js loading my data from an array in Javascript.

I started from this simple example

http://bl.ocks.org/d3noob/b3ff6ae1c120eea654b5

and I'm following the suggestions in this post

D3js take data from an array instead of a file

Here you're my code

<!DOCTYPE html>
<meta charset="utf-8">
<style> /* set the CSS */

body { font: 12px Arial;}

path { 
    stroke: steelblue;
    stroke-width: 2;
    fill: none;
}

.axis path,
.axis line {
    fill: none;
    stroke: grey;
    stroke-width: 1;
    shape-rendering: crispEdges;
}

</style>
<body>

<!-- load the d3.js library -->    
<script src="http://d3js.org/d3.v3.min.js"></script>

<script>

// Set the dimensions of the canvas / graph
var margin = {top: 30, right: 20, bottom: 30, left: 50},
    width = 600 - margin.left - margin.right,
    height = 270 - margin.top - margin.bottom;

// Parse the date / time
var parseDate = d3.time.format("%d-%b-%y").parse;

// Set the ranges
var x = d3.time.scale().range([0, width]);
var y = d3.scale.linear().range([height, 0]);

// Define the axes
var xAxis = d3.svg.axis().scale(x)
    .orient("bottom").ticks(5);

var yAxis = d3.svg.axis().scale(y)
    .orient("left").ticks(5);

// Define the line
var valueline = d3.svg.line()
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.close); });

// Adds the svg canvas
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 = [
  {time: "01-01-2000", value:23.2},
  {time: "02-01-2000", value:22.2},
  {time: "03-01-2000", value:21.5},
  {time: "04-01-2000", value:21.2},
  {time: "05-01-2000", value:20.8},
  {time: "06-01-2000", value:21.6},
  {time: "01-02-2000", value:21.6},
  {time: "01-03-2000", value:22.0},
  {time: "01-04-2000", value:22.4},
  {time: "01-05-2000", value:23.3},
];


// Get the data
//d3.csv("data.csv", function(error, data) {
        data.forEach(function(d) {
            d.date = parseDate(d.time);
            d.close = +d.value;
        });

    // Scale the range of the data
    x.domain(d3.extent(data, function(d) { return d.time; }));
    y.domain([0, d3.max(data, function(d) { return d.value; })]);

    // Add the valueline path.
    svg.append("path")
        .attr("class", "line")
        .attr("d", valueline(data));

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

    // Add the Y Axis
    svg.append("g")
        .attr("class", "y axis")
        .call(yAxis);

//});

</script>
</body>

when I try to execute I obtain the following error in my web console

d3.v3.min.js:1 Error: <path> attribute d: Expected number, "MNaN,0.9012875536…".

Any suggestions / example will be appreciated!!!

Cesare

Lukasz Wiktor · Accepted Answer · 2016-06-28 12:31:52Z

2

You have another date format. Try this:

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

And use d.date instead of d.time in your x.domain:

x.domain(d3.extent(data, function(d) { return d.time; }));

Demo: https://embed.plnkr.co/SGRyjWxjReXq8ENLd4LI/

answered Jun 28, 2016 at 12:31

Lukasz Wiktor

20.5k6 gold badges73 silver badges83 bronze badges

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2 Comments

Cesare Over a year ago

ok it's working now!!! Just another quicky question: if I need to add also hours in my time, so for example 01-01-2000-10:30:23 (gg-mm-yyyy-hh:mm.sec), what is the right format date in D3? I can change the structure of my time if necessary but I've to manage minutes and seconds .... Thank you in advance!

Lukasz Wiktor Over a year ago

you can figure it out easily from d3.time.format docs

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