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D3.js area.defined() Method

  • Last Updated : 02 Sep, 2020

The d3.area.defined() method lets you specify whether there is data defined for a given data point or not. If this method returns false, this means that data point exists, else true.

Syntax:

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d3.area.defined(data_point)

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

  • data_point: This parameter is the data_point to be checked.

Return Value: This method returns a boolean value.



Example 1: 

HTML




<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
  
    <script src=
    </script>
</head>
  
<body>
    <h1 style="text-align: center; color: green;">
        GeeksforGeeks
    </h1>
  
    <h3 style="text-align: center;">
        D3.js | d3.area.defined() Method
    </h3>
  
    <center>
        <svg id="gfg" width="200" height="200">
        </svg>
    </center>
  
    <script>
        var data = [
          {x: 50, y: 10},
          {x: 150, y: 30},
          {x: 200, y: 150},
          {x: 250, y: 10},
          {x: 300, y: 150},
          {x: 350, y: 50},
          {x: 400, y: 190}];
  
        var xScale = d3.scaleLinear()
            .domain([0, 8]).range([25, 200]);
        var yScale = d3.scaleLinear()
            .domain([0,20]).range([200, 25]);
  
        var Gen = d3.area()
          .x((p) => p.x)
          .y0((p) => p.y*2)
          .y1((p) => p.y*4)
          
          // Excluding 3rd index
          .defined((d,i) => (i != 3));
  
        d3.select("#gfg")
          .append("path")
          .attr("d", Gen(data))
          .attr("fill", "green")
          .attr("stroke", "black");
    </script>
</body>
  
</html>

Output:

Example 2:

HTML




<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
  
    <script src=
    </script>
</head>
  
<body>
    <h1 style="text-align: center; color: green;">
        GeeksforGeeks
    </h1>
  
    <h3 style="text-align: center;">
        D3.js | d3.area.defined() Method
    </h3>
  
    <center>
        <svg id="gfg" width="250" height="200"></svg>
    </center>
  
    <script>
        var points = [
          {xpoint: 25,  ypoint: 150},
          {xpoint: 75,  ypoint: 50},
          {xpoint: 100, ypoint: 150},
          {xpoint: 100, ypoint: 50},
          {xpoint: 200, ypoint: 150}];
  
  
        var Gen = d3.area()
          .x((p) => p.xpoint)
          .y0((p) => p.ypoint/2)
          .y1((p) => p.ypoint)
          
          // Excluding 2nd index
          .defined((d,i) => (i != 2));
  
        d3.select("#gfg")
          .append("path")
          .attr("d", Gen(points))
          .attr("fill", "green")
          .attr("stroke", "black");
  
    </script>
</body>
  
</html>

Output:




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