d3折线图 - 如何从Y轴右侧开始直线？

Question

I have a line graph with dates representing the X-Axis. Rather than my line start on the Y-axis, I'd like to move it over to the right slightly so that it's a bit more readable. If possible, I'd also like to add a date to my list of X-Axis ticks. So basically, if I have an array of 5 dates such as:

{'March 19, 2018', 'April 24, 2018', 'May 19, 2018', 'June 4, 2018', 'July 6, 2018'}

I would want March 19, 2018 to NOT show up directly on the X-axis = 0. However, I'd still like to have a tick value on the X-axis = 0 such as the first date in my array minus one month. Does this make sense? Is this something that can easily be done with d3?

const circleLabelDrawDuration = 700;
const minDate = data[0].pullDate.setMonth(data[0].pullDate.getMonth() - 4);
const maxDate = data[data.length - 1].pullDate;

const xAxis = d3.scaleTime().domain([minDate, maxDate]).range([0, width]);

svg.append('g').call(d3.axisBottom(xAxis).ticks(pullDates.length).tickValues(pullDates).tickFormat(d3.timeFormat("%b %Y")))
.attr('transform', `translate(0,${height})`).selectAll('text')
.style('text-anchor', 'end').attr('dx', '-.8em').attr('dy', '-.15em').attr('transform', 'rotate(-50)');

Answer 1

I would do something like the following when setting your x-domain. I find offsets to be quite useful. Using some d3 functions to make it easier.

const monthInMs = 2.628e+9 // this is 1 month in ms
const xMin = +d3.min(dataArray, (d) => d.timestamp) - monthInMs;
const xMax = +d3.max(dataArray, (d) => d.timestamp) + monthInMs;
xScale.domain([xMin, xMax]);

I added the + in front of d3.min to ensure that the returned value is a number and not a date object. I gave both min and max so that you could have some padding on both sides, but you only really need to use the ones that you would like.