D3.js area.defined() 方法

d3.area.defined () 方法允许您指定是否为给定数据点定义了数据。如果此方法返回 false，则表示数据点存在，否则为 true。

句法：

d3.area.defined(data_point)

参数：此函数接受如上所述和下文所述的单个参数。

• data_point：这个参数是要检查的data_point。

返回值：此方法返回一个布尔值。

示例 1：

HTML

    
  
    
    

  

    
        GeeksforGeeks
    
  
    
        D3.js | d3.area.defined() Method
    
  
    
        
        
    
  
    
        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");
    

  

输出：

示例 2：

HTML

    
  
    
    

  

    
        GeeksforGeeks
    
  
    
        D3.js | d3.area.defined() Method
    
  
    
        
    
  
    
        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");
  
    

  

输出：