D3.js node.sum()函数

d3.js 中的node.sum()函数用于评估特定节点的指定值函数。此函数的 node.value 属性包含指定函数返回的值。

句法：

node.sum(value);

参数：此函数接受如上所述和如下所述的单个参数：

• value：这需要为每个节点评估一个函数。

返回值：此函数返回一个对象。

下面给出了上面给出的函数的几个例子。

示例 1：

HTML

 
 
 
     
     
    
    
 
  
 
     
       // Constructing a tree
        var tree={
            name: "rootNode", // Root node
            children: [
                {
                    name: "child1", // Child of root node
                    value: 2
                },
                {
                    name: "child2", // Child of root node
                    value: 3,
                    children: [
                        {
                            name: "grandchild1", // Child of child2
                            value: 1,
                            children:[
                                {name: "grand_granchild1_1",value: 4},                              
                                // Child of grandchild1
                                {name: "grand_granchild1_2",value: 5}                     
                               // Child of grandchild1
                            ]
                        },
                        {
                            name: "grandchild2",
                            children:[
                                {name: "grand_granchild2_1"},  
                                // Child of grandchild2
                                {name: "grand_granchild2_2"}  
                                // Child of grandchild2
                            ]
                        },
                    ]
                }
            ]
        };
  
        var obj = d3.hierarchy(tree);
        var grandchild2=obj.children[1].children[1];
          
        var sum=obj.sum(d=>d.value);
        console.log(sum);
        console.log("The sum of value is: ",sum.value);
     
 

输出：

示例 2：

HTML

 
 
 
     
     
    
    
 
 
     
    // Constructing a tree
        var tree={
            name: "rootNode", // Root node
            children: [
                {value:1},
                {value:2},
                {value:3},
                {value:4},
                {value:5},
                {value:6},
            ]
        };
  
        var obj = d3.hierarchy(tree);
          
        var sum=obj.sum(d=>d.value*12);
        // 1 + 2 + 3 + 4 + 5 + 6 = 21*12=252
        console.log(sum);
        console.log("The value is: ",sum.value);
     
 

输出：