Question

我有此数据，

json：

const elements = chart.selectAll('g.cols.axis text');

// Get the values 
const xValue = elements.attr('x');
const yValue = elements.attr('y');

elements.attr('x', null)
  .attr('y', null)
  .style("text-anchor", "end")
  .attr('transform', `translate(${xValue},${yValue}) rotate(90)`);

我想做这样的事情：

var data = [{a:1,b:{amount: 10}, c:1},
            {a:2,b:{amount: 20}, c:1}, 
            {a:1,b:{amount: 30}, c:2}
           ];

有什么想法吗？

Answer 1

您正在尝试对对象数组中的属性求和。

这将为您做到：

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<title>three.js css2d - label</title>
		<style>
			body {
				background-color: #000;
				margin: 0;
				overflow: hidden;
			}
			#info {
				position: absolute;
				top: 0px;
				width: 100%;
				color: #FFF;
				padding: 5px;
				font-family: Monospace;
				font-size: 13px;
				text-align: center;
				z-index: 1;
			}

			.label{
				color: #FFF;
				font-family: sans-serif;
				padding: 2px;
				background: rgba( 0, 0, 0, .6 );
			}

			a {
				color: #000000;
			}

		</style>
	</head>
	<body>
		<div id="info"><a href="http://threejs.org" target="_blank" rel="noopener">three.js</a> - three.js css2d - label</div>

        <script src="http://threejs.org/build/three.js"></script>
        
        <script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>

		<script src="https://threejs.org/examples/js/renderers/CSS2DRenderer.js"></script>

        <script src="https://threejs.org/examples/js/effects/StereoEffect.js"></script>

		<script>

            var camera, scene, renderer, effect, labelRenderer;

			var clock = new THREE.Clock();
			var textureLoader = new THREE.TextureLoader();

			var earth, moon;

			init();
			animate();

			function init() {

				var EARTH_RADIUS = 1;
				var MOON_RADIUS = 0.27;

				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 1000 );
				camera.position.set( 10, 5, 20 );

				var controls = new THREE.OrbitControls( camera );

				scene = new THREE.Scene();

				var dirLight = new THREE.DirectionalLight( 0xffffff );
				dirLight.position.set( 0, 0, 1 );
				scene.add( dirLight );

				var axesHelper = new THREE.AxesHelper( 5 );
				scene.add( axesHelper );

				//

				var earthGeometry = new THREE.SphereBufferGeometry( EARTH_RADIUS, 16, 16 );
				var earthMaterial = new THREE.MeshPhongMaterial( {
					specular: 0x333333,
					shininess: 5,
					map: textureLoader.load('https://threejs.org/examples/textures/planets/earth_atmos_2048.jpg'),
					specularMap: textureLoader.load('https://threejs.org/examples/textures/planets/earth_specular_2048.jpg'),
					normalMap: textureLoader.load('https://threejs.org/examples/textures/planets/earth_normal_2048.jpg'),
					normalScale: new THREE.Vector2( 0.85, 0.85 )
				} );
				earth = new THREE.Mesh( earthGeometry, earthMaterial );
				scene.add( earth );

				var moonGeometry = new THREE.SphereBufferGeometry( MOON_RADIUS, 16, 16 );
				var moonMaterial = new THREE.MeshPhongMaterial( {
					shininess: 5,
					map: textureLoader.load('https://threejs.org/examples/textures/planets/moon_1024.jpg')
				} );
				moon = new THREE.Mesh( moonGeometry, moonMaterial );
				scene.add( moon );

				//

				var earthDiv = document.createElement( 'div' );
				earthDiv.className = 'label';
				earthDiv.textContent = 'Earth';
				earthDiv.style.marginTop = '-1em';
				var earthLabel = new THREE.CSS2DObject( earthDiv );
				earthLabel.position.set( 0, EARTH_RADIUS, 0 );
				earth.add( earthLabel );

				var moonDiv = document.createElement( 'div' );
				moonDiv.className = 'label';
				moonDiv.textContent = 'Moon';
				moonDiv.style.marginTop = '-1em';
				var moonLabel = new THREE.CSS2DObject( moonDiv );
				moonLabel.position.set( 0, MOON_RADIUS, 0 );
				moon.add( moonLabel );

				//

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				document.body.appendChild( renderer.domElement );

				labelRenderer = new THREE.CSS2DRenderer();
				labelRenderer.setSize( window.innerWidth, window.innerHeight );
				labelRenderer.domElement.style.position = 'absolute';
				labelRenderer.domElement.style.top = 0;
				document.body.appendChild( labelRenderer.domElement );

				effect = new THREE.StereoEffect(renderer);
			    //effect.setEyeSeparation(1);
				effect.setSize(window.innerWidth, window.innerHeight);
            }

			function animate() {

				requestAnimationFrame( animate );

				var elapsed = clock.getElapsedTime();

				moon.position.set( Math.sin( elapsed ) * 5, 0, Math.cos( elapsed ) * 5 );

				//renderer.render( scene, camera );
				effect.render(scene, camera);

				labelRenderer.render(scene, camera);

			}

		</script>
	</body>
</html>

然后您可以使用let sum = []; data.forEach(function(el){ if(sum[el.a] == undefined) sum[el.a] = []; if(sum[el.a][el.c] == undefined) sum[el.a][el.c] = 0; sum[el.a][el.c] += el.b.amount });访问a = 1，c = 2的总和。

此代码将与需要添加的较大数据集一起使用。

Answer 2

如果我正确理解了您的问题，那么您在问如何对JSON对象执行分组和聚合。由于SQL只能在数据库领域中使用，因此您需要使用JavaScript函数，例如forEach（），map（），filter（），reduce（）等。

为方便起见，我建议使用Lodash或Underscore之类的库。

以下是使用Lodash的示例：

let data = [
  {a:1, b:{amount: 10}, c:1},
  {a:2, b:{amount: 20}, c:1},
  {a:1, b:{amount: 30}, c:2}
];

let results = _.sumBy(data, 'b.amount');

console.log(results);

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.11/lodash.min.js"></script>

使用这些库可以消除编写自己的脚本的许多复杂性，尤其是在处理嵌套对象和数组时。

我建议尽可能使用纯JS，并仅在必要时使用库。

对象json数据中的javscript / jquery对象

2 个答案: