D3.js areaRadial.defined() Method

Last Updated : 02 Sep, 2020

The areaRadial.defined() method in D3.js lets one specify whether data is defined for a given data point or not. The value is checked for each point using the boolean value or function specified as a parameter to this method. The checked value is kept if this method returns true, otherwise it is omitted.

Syntax:

areaRadial.defined( data_point )

Parameters: This function accepts a single parameter as mentioned above and described below:

data_point: It is a boolean value or function that is used to check every point.

Return Value: This method returns a boolean value.

Below given are a few examples of areaRadial.defined() method in D3.js:

Example 1:

HTML

<!DOCTYPE html> 
<html> 
<head> 
  <script src= 
"https://d3js.org/d3.v5.min.js"> 
  </script> 
</head> 
<body> 
  <h1 style="text-align: center; 
             color: green;"> 
    GeeksforGeeks 
  </h1> 
  <h3 style="text-align: center;"> 
    D3.js | areaRadial.defined() Method 
  </h3> 
  <center> 
    <svg id="gfg" width="500" height="500"> 
      <g transform="translate(180,180)"></g> 
    </svg> 
  </center> 
  <script> 
    var data = [ 
      { x: 10, y: 1 }, 
      { x: 15, y: 3 }, 
      { x: 20, y: 5 }, 
      { x: 25, y: 7 }, 
      { x: 30, y: 9 }, 
      { x: 35, y: 11 }, 
      { x: 40, y: 13 }]; 
  
    var xScale = d3.scaleLinear() 
        .domain([0, 8]) 
        .range([25, 200]); 
    var yScale = d3.scaleLinear() 
        .domain([0, 20]) 
        .range([200, 25]); 
  
    var Gen = d3.areaRadial() 
      .angle(d => xScale(d.x / 3)) 
      .innerRadius(d => yScale(d.y / 2)) 
      .outerRadius(d => yScale(d.y)) 
      // Omitting 4th index 
      .defined((d, i) => (i != 4)); 
  
    d3.select("#gfg") 
      .select("g") 
      .append("path") 
      .attr("d", Gen(data)) 
      .attr("fill", "green") 
      .attr("stroke", "black"); 
  </script> 
</body> 
</html>

Output:

Example 2:

HTML

<!DOCTYPE html> 
<html> 
<head> 
  <script src= 
"https://d3js.org/d3.v5.min.js"> 
  </script> 
</head> 
<body> 
  <h1 style="text-align: center; 
             color: green;"> 
    GeeksforGeeks 
  </h1> 
  <h3 style="text-align: center;"> 
    D3.js | areaRadial.defined() Method 
  </h3> 
  <center> 
    <svg id="gfg" width="200" height="200"> 
      <g transform="translate(100,100)"></g> 
    </svg> 
  </center> 
  <script> 
    var points = [ 
      { x: 0, y: 0 }, 
      { x: 2, y: 3 }, 
      { x: 4, y: 1 }, 
      { x: 6, y: 8 }, 
      { x: 8, y: 17 }, 
      { x: 10, y: 15 }, 
      { x: 12, y: 20 }]; 
  
    var xScale = d3.scaleLinear() 
        .domain([0, 6]) 
        .range([0, 2 * Math.PI]); 
    var yScale = d3.scaleLinear() 
        .domain([0, 20]) 
        .range([90, 30]); 
  
    var Gen = d3.areaRadial() 
      .angle(d => xScale(d.x / 2)) 
      .innerRadius(d => yScale(d.y) / 2) 
      .outerRadius(d => yScale(d.y)) 
      // Omitting 2nd index 
      .defined((d, i) => (i != 2)); 
  
    d3.select("#gfg") 
      .select("g") 
      .append("path") 
      .attr("d", Gen(points)) 
      .attr("fill", "green") 
      .attr("stroke", "black"); 
  </script> 
</body> 
</html>