问题
I have a nvd3 line chart which displays a time series and can't get the ticks on the x axis right.
For longer time spans, it works as expected. But for shorter time spans (here: 12/31/05 to 01/01/06), the same date is displayed for multiple ticks:
Please have a look at the code for this chart on JSFiddle
I want the chart to only display ticks at data points, and not in between. Is that possible with a line chart? From my understanding, it is possible with d3, but I can't figure out if this functionality is exposed by nvd3.
I've tried explicitly setting the number of ticks with chart.xAxis.ticks() without success. The only thing that has any effect is explicitly setting the tick values with chart.xAxis.tickValues([...]), but I would prefer not having to calculate them myself.
回答1:
The way to solve this in general is with custom multi-scale time formats. Note that this example itself will not work with NVD3 because it uses an older version of D3, the examples below will though.
The problem in your case is that the ticks aren't "clean" divisions of time and if you apply a multi-scale format, you get something like this. It always shows the more fine-grained format because anything else would involve a loss of precision.
You can however use a simple heuristic to show the date instead of the time if the hour is less than 3, which works reasonably well in your case. See here for an example. The proper way to do this would be to make your ticks clean divisions.
Which brings us to your actual question. There's no other way than to explicitly set .tickValues() for what you want to do, but you can compute the x positions in your data quite easily:
var xvalues = [],
tmp = data.map(function(e) {
return e.values.map(function(d) { return d[0]; });
});
xvalues.concat.apply(xvalues, tmp);
The code is not the prettiest because it's a nested structure, but fairly straightforward. Using this, you can set your tick values explicitly, full example here.
来源：https://stackoverflow.com/questions/21263742/nvd3-configuring-ticks-on-axis