bizcharts
Version:
bizcharts
131 lines • 4.78 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
// 认为是nice的刻度
var SNAP_COUNT_ARRAY = [1, 1.2, 1.5, 2, 2.2, 2.4, 2.5, 3, 4, 5, 6, 7.5, 8, 10];
var DEFAULT_COUNT = 5; // 默认刻度值
exports.default = (function (cfg) {
var _a = cfg || {}, tickCount = _a.tickCount, tickInterval = _a.tickInterval;
var _b = cfg || {}, min = _b.min, max = _b.max;
min = isNaN(min) ? 0 : min;
max = isNaN(max) ? 0 : max;
var count = tickCount && tickCount >= 2 ? tickCount : DEFAULT_COUNT;
// 计算interval， 优先取tickInterval
var interval = tickInterval || getBestInterval({ tickCount: count, max: max, min: min });
// 通过interval计算最小tick
var minTick = Math.floor(min / interval) * interval;
// 如果指定了tickInterval, count 需要根据指定的tickInterval来算计
if (tickInterval) {
var intervalCount = Math.abs(Math.ceil((max - minTick) / tickInterval)) + 1;
// tickCount 作为最小 count 处理
count = Math.max(count, intervalCount);
}
var ticks = [];
var tickLength = 0;
var fixedLength = getFixedLength(interval);
while (tickLength < count) {
ticks.push(toFixed(minTick + tickLength * interval, fixedLength));
tickLength++;
}
return ticks;
});
var DECIMAL_LENGTH = 12;
function getFactor(number) {
// 取正数
number = Math.abs(number);
var factor = 1;
if (number === 0) {
return factor;
}
// 小于1,逐渐放大
if (number < 1) {
var count = 0;
while (number < 1) {
factor = factor / 10;
number = number * 10;
count++;
}
// 浮点数计算出现问题
if (factor.toString().length > DECIMAL_LENGTH) {
factor = parseFloat(factor.toFixed(count));
}
return factor;
}
// 大于10逐渐缩小
while (number > 10) {
factor = factor * 10;
number = number / 10;
}
return factor;
}
// 获取最佳匹配刻度
function getBestInterval(_a) {
var tickCount = _a.tickCount, min = _a.min, max = _a.max;
// 如果最大最小相等，则直接按1处理
if (min === max) {
return 1 * getFactor(max);
}
// 1.计算平均刻度间隔
var avgInterval = (max - min) / (tickCount - 1);
// 2.数据标准归一化 映射到[1-10]区间
var factor = getFactor(avgInterval);
var calInterval = avgInterval / factor;
var calMax = max / factor;
var calMin = min / factor;
// 根据平均值推算最逼近刻度值
var similarityIndex = 0;
for (var index = 0; index < SNAP_COUNT_ARRAY.length; index++) {
var item = SNAP_COUNT_ARRAY[index];
if (calInterval <= item) {
similarityIndex = index;
break;
}
}
var similarityInterval = getInterval(similarityIndex, tickCount, calMin, calMax);
// 小数点位数还原到数据的位数, 因为similarityIndex有可能是小数，所以需要保留similarityIndex自己的小数位数
var fixedLength = getFixedLength(similarityInterval) + getFixedLength(factor);
return toFixed(similarityInterval * factor, fixedLength);
}
function getInterval(startIndex, tickCount, min, max) {
var verify = false;
var interval = SNAP_COUNT_ARRAY[startIndex];
// 刻度值校验，如果不满足，循环下去
for (var i = startIndex; i < SNAP_COUNT_ARRAY.length; i++) {
if (intervalIsVerify({ interval: SNAP_COUNT_ARRAY[i], tickCount: tickCount, max: max, min: min })) {
// 有符合条件的interval
interval = SNAP_COUNT_ARRAY[i];
verify = true;
break;
}
}
// 如果不满足, 依次缩小10倍，再计算
if (!verify) {
return 10 * getInterval(0, tickCount, min / 10, max / 10);
}
return interval;
}
// 刻度是否满足展示需求
function intervalIsVerify(_a) {
var interval = _a.interval, tickCount = _a.tickCount, max = _a.max, min = _a.min;
var minTick = Math.floor(min / interval) * interval;
if (minTick + (tickCount - 1) * interval >= max) {
return true;
}
return false;
}
// 计算小数点应该保留的位数
function getFixedLength(num) {
var str = num.toString();
var index = str.indexOf('.');
var indexOfExp = str.indexOf('e-');
var length = indexOfExp >= 0 ? parseInt(str.substr(indexOfExp + 2), 10) : str.substr(index + 1).length;
if (length > 20) {
// 最多保留20位小数
length = 20;
}
return length;
}
// @antv/util fixedbase不支持科学计数法的判断，需要提mr
function toFixed(v, length) {
return parseFloat(v.toFixed(length));
}
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