D3.js curveMonotoneX() Method

Last Updated : 09 Sep, 2020

The d3.curveMonotoneX interpolator assumes that the data is sorted according to the x coordinates otherwise sort the data accordingly. This curve method produces a cubic spline that preserves monotonicity in y, assuming monotonicity in x.

Syntax:

d3.curveMonotoneX()

Parameters: This method does not accept any parameters.

Return Value: This method does not return any value.

Example 1:

<!DOCTYPE html> 
<html> 
  
<head> 
    <meta charset="utf-8"> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.2/d3.min.js"> 
    </script> 
</head> 
  
<body> 
    <h1 style="text-align:center; color:green;"> 
        GeeksforGeeks 
    </h1> 
  
    <center> 
        <svg id="gfg" width="250" height="250"></svg> 
    </center> 
  
    <script> 
        var data = [ 
          {x: 0, y: 0}, 
          {x: 1, y: 3}, 
          {x: 2, y: 15}, 
          {x: 5, y: 1}, 
          {x: 6, y: 15}, 
          {x: 7, y: 5}, 
          {x: 8, y: 19}]; 
  
        var xScale = d3.scaleLinear() 
          .domain([0, 8]).range([25, 200]); 
        var yScale = d3.scaleLinear() 
          .domain([0, 20]).range([200, 25]); 
  
        var line = d3.line() 
          .x((d) => xScale(d.x)) 
          .y((d) => yScale(d.y)) 
          .curve(d3.curveMonotoneX); 
  
        d3.select("#gfg") 
          .append("path") 
          .attr("d", line(data)) 
          .attr("fill", "none") 
          .attr("stroke", "green"); 
    </script> 
</body> 
</html>

Output:

Example 2: Sorting the unsorted points by the x-axis then rendering the curve.

<!DOCTYPE html> 
<html> 
  
<head> 
    <meta charset="utf-8"> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.2/d3.min.js"> 
    </script> 
</head> 
  
<body> 
    <h1 style="text-align:center; color:green;"> 
        GeeksforGeeks 
    </h1> 
  
    <center> 
        <svg id="gfg" width="250" height="200"></svg> 
    </center> 
  
    <script> 
        var points = [ 
          {xpoint: 75,  ypoint: 150}, 
          {xpoint: 25,  ypoint: 5}, 
          {xpoint: 150, ypoint: 115}, 
          {xpoint: 100, ypoint: 5}, 
          {xpoint: 200, ypoint: 150}]; 
  
        // Sorting the points by x axis 
        points.sort((a, b) => a.xpoint - b.xpoint); 
  
        var Gen = d3.line() 
          .x((p) => p.xpoint) 
          .y((p) => p.ypoint) 
          .curve(d3.curveMonotoneX); 
  
        d3.select("#gfg") 
          .append("path") 
          .attr("d", Gen(points)) 
          .attr("fill", "none") 
          .attr("stroke", "green"); 
  
    </script> 
</body> 
</html>