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D3.js brush.clear() Function
  • Last Updated : 01 Sep, 2020

The brush.clear() Function in D3.js is used to set the active selection of the brush on the specified group. It is an alias for brush.move with the null selection.

Syntax:

brush.clear(group);

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

  • group: This parameter is the specified group on which brush is implemented.

Return Value: This function returns the array that defines the brush selection for that element.

Below programs illustrate the brush.clear() function in D3.js



Example 1:

HTML




<!DOCTYPE html>  
<html>  
        
<head>  
    <script src=
    </script
</head>  
    
<body>  
    <center>
        <h1 style="color:green;">GeeksForGeeks</h1>
  
        <h3>D3.js | brush.clear() Function  </h3>
          
        <button>Click</button>
        <br>
        <br>
        <svg width="500" height="100" 
             style="background-color: #aaf2ef;">
        </svg
          
        <script>  
            // Selecting SVG element 
            const svg = d3.select("svg");
              
            const g = svg.append("g");
              
            // Creating a brush using the  
            // d3.brush function 
            g.call(d3.brush());
              
            // Use of brush.move() function
            d3.select("button").on("click", function() {
                g.call(d3.brush().clear)
            });     
        </script>  
    </center>
</body>  
    
</html>

Output:

Example 2:

HTML




<!DOCTYPE html>  
<html>  
        
<head>  
    <meta charset="utf-8">
        
    <script src=
    </script
      
    <style>
  
        circle {
          fill-opacity: 0.2;
        }
          
        circle.active {
          fill-opacity: 0.8;
          stroke: red;
          fill: green;
        }
  
    </style>
</head>  
    
<body>  
    <center>
        <h1 style="color:green;">GeeksForGeeks</h1>
  
        <h3>D3.js | brush.clear() Function  </h3>
          
        <svg width="500" height="200"></svg>
          
        <script>  
            var data = d3.range(50).map(Math.random);
  
            var svg = d3.select("svg"),
                margin = {top: 10, right: 50,
                        bottom: 50, left: 50},
                width = +svg.attr("width") - 
                        margin.left - margin.right,
                height = +svg.attr("height") - 
                        margin.top - margin.bottom,
                g = svg.append("g")
                    .attr("transform", "translate(" 
                    + margin.left + "," + margin.top + ")"
                    );
  
            var x = d3.scaleLinear().range([0, width]),
                y = d3.randomNormal(height / 2, height / 8),
                z = d3.scaleLinear().range([0, height]);
  
            var brush = d3.brushX()
                .extent([[0, 0], [width, height]])
                .on("start brush end", brushmoved);
  
            g.append("g")
                .attr("class", "axis axis--x")
                .attr("transform", "translate(0,0)")
                .call(d3.axisLeft(z).ticks(3));
  
            var circle = g.append("g")
                .attr("class", "circle")
                .selectAll("circle")
                .data(data)
                .enter().append("circle")
                .attr("transform", function (d) { 
                    return "translate(" 
                    + x(d) + "," + y() + ")"; 
                })
                .attr("r", 10);
  
            var gBrush = g.append("g")
                .attr("class", "brush")
                .call(brush);
  
            gBrush.call(brush.clear);
  
            var bs = "";
            function brushmoved() {
              var s = d3.event.selection;
                
              if (d3.event.type === "start"){
                bs = d3.event.selection;
              
              else if (d3.event.type === "end"){
                  
                if (bs[0] !== s[0] && bs[1] !== s[1]) {
                  console.log('moved both');
                
                else if (bs[0] !== s[0]) {
                  console.log('moved left');
                
                else {
                  console.log('moved right');
                }
              }
                
              if (s == null) {
                handle.attr("display", "none");
                circle.classed("active", false);
              
              else {
                var sx = s.map(x.invert);
                circle.classed("active", function (d) {
                    return sx[0] <= d && d <= sx[1]; 
                });
                handle.attr("display", null)
                .attr("transform", function (d, i) {
                    return "translate("
                    + s[i] + "," + height / 2 + ")"; 
                });
              }
            }
              
        </script>  
    </center>
</body>  
    
</html>

Output:




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