javascript - 是否可以在 D3.js 中找到刻度之间的距离？

Question

有没有办法找出 x 轴上刻度线之间的距离？我将序数刻度与 rangeRoundBands 一起使用，告诉我它没有刻度函数。

var x= d3.scale.ordinal().rangePoints([_margin.left, cWidth]);
x.domain(['Dec','Jan']);
var testTicks = x.ticks(2);

它可以很好地生成轴(无法发布图像)但我无法弄清楚如何获得距离

(编辑:添加 x.domain)

Answer 1

var data         = [45, 31, 23], // whatever your data is
    graphHeight  = 400,
    // however many ticks you want to set
    numberTicksY = 4,
    // set y scale
    // (hardcoded domain in this example to min and max of data vals > you should use d3.max real life)
    y            = d3.scale.linear().range(graphHeight, 0]).domain(23, 45), 
    yAxis        = d3.svg.axis().scale(y).orient("left").ticks(numberTicksY),
    // eg returns -> [20, 30, 40, 50]
    tickArr      = y.ticks(numberTicksY),
    // use last 2 ticks (cld have used first 2 if wanted) with y scale fn to determine positions
    tickDistance = y(tickArr[tickArr.length - 1]) - y(tickArr[tickArr.length - 2]);