d3.js - d3 v4 scaleBand ticks

Question

I have data like the following

date,values
2016-10-01,10
2016-10-02,20
2016-10-03,30
2016-10-04,5
2016-10-05,50
2016-10-06,2
2016-10-07,7
2016-10-08,17

and am generating a bar chart using the following code

var margin = {top: 20, right: 20, bottom: 70, left: 40},
width = 800 - margin.left - margin.right,
height = 400 - margin.top - margin.bottom;

var parseDate = d3.timeParse("%Y-%m-%d");

var x = d3.scaleBand().range([0, width]);

var y = d3.scaleLinear().range([height, 0]);

var xAxis = d3.axisBottom(x);

var yAxis = d3.axisLeft(y);

var tip = d3.tip()
.attr('class', 'd3-tip')
.offset([-10, 0])
.html(function(d) {
return "<strong>Month of " + d.date + ":</strong> <span style='color:red'>" + d.value + " sales</span>";
})

var svg = d3.select("#barg").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", 
      "translate(" + margin.left + "," + margin.top + ")");
svg.call(tip);
data = d3.csvParse(d3.select("pre#data2").text());
data.forEach(function(d) {
d.date = parseDate(d.date);
d.value = +d.value;
});

x.domain(data.map(function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.value; })]);

svg.append("g")
  .attr("transform", "translate(0," + height + ")")
  .call(xAxis)
  .selectAll("text")
  .style("text-anchor", "end")
  .attr("dx", "-.8em")
  .attr("dy", "-.55em")
  .attr("transform", "rotate(-90)" )

svg.append("g")
  .call(yAxis)
  .append("text")
  .attr("transform", "rotate(-90)")
  .attr("y", 6)
  .attr("dy", ".71em")
  .style("text-anchor", "end")
  .text("Value ($)");

svg.selectAll(".bar")
  .data(data)
  .enter().append("rect")
  .attr("class", "bar")
  .attr("x", function(d) { return x(d.date); })
  .attr("width", x.bandwidth() - 5)
  .attr("y", function(d) { return y(d.value); })
  .attr("height", function(d) { return height - y(d.value); })
  .on('mouseover', tip.show)
  .on('mouseout', tip.hide)

So the problem I am having is that I have ordinal data, but for large cardinality (for instance, 120 data points) The x axis has way too many ticks. I have tried a few things like tickValues, but when I use this, my x axis tick points all show up on top of each other. Ideally I would like 10 tick points or so, when the cardinality is high. Any ideas?

Answer 1

This can be done using tickValues indeed. For instance, in this demo, we have 200 values, so the axis is absolutely crowded:

var svg = d3.select("body")
  .append("svg")
  .attr("width", 500)
  .attr("height", 100);

var data = d3.range(200);

var xScale = d3.scaleBand()
  .domain(data.map(function(d){ return d}))
  .range([10, 490]);

var xAxis = d3.axisBottom(xScale);

var gX = svg.append("g").call(xAxis);

<script src="https://d3js.org/d3.v4.min.js"></script>