我知道那里有图表库,但我想亲自创建我自己的自定义图表库。
我从 another person 那里找到了一些工作,他用 javascript 从数组创建了一个饼图,只不过他是基于百分比的。
我一直在尝试重新设计它,以便它:
正如您在运行下面的代码时所看到的,除非您预先计算了百分比,否则它不会根据数据形成一个完整的圆圈。
我的目标是将所有
percent: x
替换为 value: y
,以便您可以使用原始值:
const slices = [
{ value: 1024 },
{ value: 5684 },
{ value: 125 },
];
let sum = slices.reduce(function (a, b) {
return a + b.value
}, 0);
然后在循环中,您可以使用
slice.value / sum
来表示饼图的百分比。只是它似乎不像原始百分比值那样工作。
// variables
const svgEl = document.querySelector('svg');
const slices = [
{ percent: 0.1, color: 'red' },
{ percent: 0.1, color: 'blue' },
{ percent: 0.1, color: 'green' },
];
let cumulativePercent = 0;
// coordinates
function getCoordinatesForPercent(percent) {
const x = Math.cos(2 * Math.PI * percent);
const y = Math.sin(2 * Math.PI * percent);
return [x, y];
}
// loop
slices.forEach(slice => {
// destructuring assignment sets the two variables at once
const [startX, startY] = getCoordinatesForPercent(cumulativePercent);
// each slice starts where the last slice ended, so keep a cumulative percent
cumulativePercent += slice.percent;
const [endX, endY] = getCoordinatesForPercent(cumulativePercent);
// if the slice is more than 50%, take the large arc (the long way around)
const largeArcFlag = slice.percent > 0.5 ? 1 : 0;
// create an array and join it just for code readability
const pathData = [
`M ${startX} ${startY}`, // Move
`A 1 1 0 ${largeArcFlag} 1 ${endX} ${endY}`, // Arc
`L 0 0`, // Line
].join(' ');
// create a <path> and append it to the <svg> element
const pathEl = document.createElementNS('http://www.w3.org/2000/svg', 'path');
pathEl.setAttribute('d', pathData);
pathEl.setAttribute('fill', slice.color);
svgEl.appendChild(pathEl);
});
svg {
height: 200px;
}
<svg viewBox="-1 -1 2 2" style="transform: rotate(-90deg);fill:black;"></svg>
您不必计算任何百分比(除非您想要百分比值)
让 SVG 来完成工作
pathLength
切片值:蓝色:10,金色:20,红色:30,使得:
pathLength="60"
您只需计算
stroke-dasharray
间隙(第二个值= 60 - value
)stroke-dashoffset
累计值:10、30、60
要使饼图从顶部开始,请将其旋转 -90 度(围绕 50 50 中心)
更高级的使用:https://pie-meister.github.io
<style>
svg {
width:180px;
}
</style>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
<g transform="rotate(-90 50 50)">
<path stroke-dasharray="10 50" stroke-dashoffset="10" stroke="blue"
pathLength="60"
stroke-width="50" d="M75 50a1 1 90 10-50 0a1 1 90 10 50 0" fill="none"></path>
<path stroke-dasharray="20 40" stroke-dashoffset="30" stroke="gold"
pathLength="60"
stroke-width="50" d="M75 50a1 1 90 10-50 0a1 1 90 10 50 0" fill="none"></path>
<path stroke-dasharray="30 30" stroke-dashoffset="60" stroke="red"
pathLength="60"
stroke-width="50" d="M75 50a1 1 90 10-50 0a1 1 90 10 50 0" fill="none"></path>
</g>
</svg>
const slices = [{color: 'red', value: 10}, {color: 'blue', value: 20}, {color: 'green', value: 30}];
const valueSum = slices.reduce((sum, slice) => sum + slice.value, 0);
const pctSlices = slices.map(slice => ({...slice, percent: slice.value / valueSum}));
pctSlices 数组将包含每个切片的百分比值