Limit labels number on Chart.js line chart

问题:

I want to display all of the points on my chart from the data I get, but I don't want to display all the labels for them, because then the chart is not very readable. I was looking for it in the docs, but couldn't find any parameter that would limit this.

I don't want to take only three labels for example, because then the chart is also limited to three points. Is it possible?

I have something like that right now:

If I could just leave every third-fourth label, it would be great. But I found absolutely nothing about labels options.

回答1:

Try adding the options.scales.xAxes.ticks.maxTicksLimit option:

xAxes: [{
    type: 'time',
    ticks: {
        autoSkip: true,
        maxTicksLimit: 20
    }
}]

回答2:

For concreteness, let's say your original list of labels looks like:

["0", "1", "2", "3", "4", "5", "6", "7", "8"]

If you only want to display every 4th label, filter your list of labels so that every 4th label is filled in, and all others are the empty string (e.g. ["0", "", "", "", "4", "", "", "", "8"]).

回答3:

UPDATE:

I'v updated my fork with the latest pull (as of Jan 27, 2014) from NNick's Chart.js master branch. https://github.com/hay-wire/Chart.js/tree/showXLabels

ORIGINAL ANSWER:

For those still facing this issue, I forked Chart.js a while back to solve the same problem. You can check it out on: https://github.com/hay-wire/Chart.js/tree/skip-xlabels => Older branch! Check showXLabels branch for latest pull.

How to use:

Applicable to bar chart and line chart.

User can now pass a { showXLabels: 10 } to display only 10 labels (actual displayed labels count might be a bit different depending on the number of total labels present on x axis, but it will still remain close to 10 however)

Helps a lot when there is a very large amount of data. Earlier, the graph used to look devastated due to x axis labels drawn over each other in the cramped space. With showXLabels, user now has the control to reduce the number of labels to whatever number of labels fit good into the space available to him.

See the attached images for a comparison.

Without showXLabels option:

With { showXLabels: 10 } passed into option:

Here's some discussion on it: https://github.com/nnnick/Chart.js/pull/521#issuecomment-60469304

回答4:

For anyone looking to achieve this on Chart JS V2 the following will work:

 var options =  {  
         scales: {
            xAxes: [{
                afterTickToLabelConversion: function(data){


                    var xLabels = data.ticks;

                    xLabels.forEach(function (labels, i) {
                        if (i % 2 == 1){
                            xLabels[i] = '';
                        }
                    });
                } 
            }]   
        }
}

Then pass the options variable as usual into a:

myLineChart = new Chart(ctx, {
    type: 'line',
    data: data,
    options: options
});`

回答5:

According to the chart.js github issue #12. Current solutions include:

1. Use 2.0 alpha (not production)
2. Hide x-axis at all when it becames too crowd (cannot accept at all)
3. manually control label skip of x-axis (not in responsive page)

However, after a few minutes, I thinks there's a better solution.

The following snippet will hide labels automatically. By modify xLabels with empty string before invoke draw() and restore them after then. Even more, re-rotating x labels can be applied as there's more space after hiding.

var axisFixedDrawFn = function() {
    var self = this
    var widthPerXLabel = (self.width - self.xScalePaddingLeft - self.xScalePaddingRight) / self.xLabels.length
    var xLabelPerFontSize = self.fontSize / widthPerXLabel
    var xLabelStep = Math.ceil(xLabelPerFontSize)
    var xLabelRotationOld = null
    var xLabelsOld = null
    if (xLabelStep > 1) {
        var widthPerSkipedXLabel = (self.width - self.xScalePaddingLeft - self.xScalePaddingRight) / (self.xLabels.length / xLabelStep)
        xLabelRotationOld = self.xLabelRotation
        xLabelsOld = clone(self.xLabels)
        self.xLabelRotation = Math.asin(self.fontSize / widthPerSkipedXLabel) / Math.PI * 180
        for (var i = 0; i < self.xLabels.length; ++i) {
            if (i % xLabelStep != 0) {
                self.xLabels[i] = ''
            }
        }
    }
    Chart.Scale.prototype.draw.apply(self, arguments);
    if (xLabelRotationOld != null) {
        self.xLabelRotation = xLabelRotationOld
    }
    if (xLabelsOld != null) {
        self.xLabels = xLabelsOld
    }
};

Chart.types.Bar.extend({
    name : "AxisFixedBar",
    initialize : function(data) {
        Chart.types.Bar.prototype.initialize.apply(this, arguments);
        this.scale.draw = axisFixedDrawFn;
    }
});

Chart.types.Line.extend({
    name : "AxisFixedLine",
    initialize : function(data) {
        Chart.types.Line.prototype.initialize.apply(this, arguments);
        this.scale.draw = axisFixedDrawFn;
    }
});

Please notice that clone is an external dependency.

回答6:

i had a similar type of issue, and was given a nice solution to my specific issue show label in tooltip but not in x axis for chartjs line chart. See if this helps you

回答7:

This answer works like a charm.

If you are wondering about the clone function, try this one:

var clone = function(el){ return el.slice(0); }

回答8:

In the Chart.js file, you should find (on line 884 for me)

var Line = function(...
    ...
    function drawScale(){
        ...
        ctx.fillText(data.labels[i], 0,0);
        ...

If you just wrap that one line call to fillText with if ( i % config.xFreq === 0){ ... } and then in chart.Line.defaults add something line xFreq : 1 you should be able to start using xFreq in your options when you call new Chart(ctx).Line(data, options).

Mind you this is pretty hacky.