CODEWITHSUNDEEP
d3.jslinechart
Abbas
Abbas

Reputation: 4070

d3js plotting linecharts undefined is not iterable

I'm learning d3js and I need help in creating line charts. I'm fairly successful plotting simple objects and bar charts. Line charts seems to be a steep hill to climb.

const data = [{
    "LINE1": [
      10,
      11,
      12,
      15
    ]
  },
  {
    "LINE2": [
      21,
      22,
      23,
      32
    ]
  },
  {
    "LINE3": [
      11,
      12,
      13,
      15
    ]
  }
]

// set the dimensions and margins of the graph
var margin = {
    top: 50,
    right: 100,
    bottom: 130,
    left: 120
  },
  width = 900 - margin.left - margin.right,
  height = 400 - margin.top - margin.bottom;

// append the svg object to the body of the page
var svg = d3.select("#ca")
  .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})`);

// Add X axis
var x = d3.scaleLinear()
  .domain(d3.extent(data, (d) => d.length))
  .range([0, width]);

svg.append("g")
  .attr("transform", "translate(0," + height + ")")
  .call(d3.axisBottom(x).ticks(5));

// Add Y axis
// I need help in this area, how can I get the min and max values set in the domain?
var y = d3.scaleLinear()
  .domain([0, d3.max(data, (d) => d.values)])
  .range([height, 0]);

svg.append("g")
  .call(d3.axisLeft(y));

// Draw the line
// I need help in this area, how can I get the lines plotted, js gives error in this!
svg.selectAll(".line")
  .data(data)
  .enter()
  .append("path")
  .attr("fill", "none")
  .attr("stroke", "black")
  .attr("stroke-width", 1.5)
  .attr("d", (d) => {
    console.log(d)
    var k = d3.line()
      .x((d) => x(d))
      .y((d) => y(d))
      (d.values);
    console.log(k);
    return k;
  });
<div id="ca">
</div>
<script src="https://d3js.org/d3.v6.min.js"></script>

How can I get the line charts plotted with data format I have?

Upvotes: 0

Views: 1640

Answers (1)

Ruben Helsloot
Ruben Helsloot

Reputation: 13129

I've made your example work, but there are several things you need to know here:

  1. Your data structure was very chaotic. If you want to have an array of objects as data, make sure all objects have the same keys. It's fine if you use [{y: [...]}, {y: [...]}], but [{LINE1: [...]}, {LINE2: [...]}] is very difficult to work with. I changed your data to be more like [[...], [...], [...]] as a structure.

  2. Don't create a separate d3.line for every line, just create it once and call it. It's a line factory, which means it is a function that, when called, returns a line. If it's not shared, it might use different domains and ranges, making the chart difficult or even useless.

  3. If the first argument in a function is d, the second is i, the index of the node in the array. In this case, you use that to start at x=0, and go to x=3. You used d to try to get that value.

  4. Keep in mind the structure of your data. You kept wanting to access d.values, but that never existed!

const data = Object.values({
  "LINE1": [
    10,
    11,
    12,
    15
  ],
  "LINE2": [
    21,
    22,
    23,
    32
  ],
  "LINE3": [
    11,
    12,
    13,
    15
  ]
});

var line = d3.line()
  .x((d, i) => x(i))
  .y((d) => y(d));

// set the dimensions and margins of the graph
var margin = {
    top: 50,
    right: 100,
    bottom: 130,
    left: 120
  },
  width = 900 - margin.left - margin.right,
  height = 400 - margin.top - margin.bottom;

// append the svg object to the body of the page
var svg = d3.select("#ca")
  .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})`);

// Add X axis
var x = d3.scaleLinear()
  .domain([0, d3.max(data, (d) => d.length)])
  .range([0, width]);

svg.append("g")
  .attr("transform", "translate(0," + height + ")")
  .call(d3.axisBottom(x).ticks(5));

// Add Y axis
// I need help in this area, how can I get the min and max values set in the domain?
var y = d3.scaleLinear()
  .domain([0, d3.max(data, (d) => Math.max(...d))])
  .range([height, 0]);

svg.append("g")
  .call(d3.axisLeft(y));

// Draw the line
// I need help in this area, how can I get the lines plotted, js gives error in this!
svg.selectAll(".line")
  .data(data)
  .enter()
  .append("path")
  .attr("fill", "none")
  .attr("stroke", "black")
  .attr("stroke-width", 1.5)
  .attr("d", (d) => line(d));
<div id="ca">
</div>
<script src="https://d3js.org/d3.v6.min.js"></script>

Upvotes: 1

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