missing value in highcharts line graph results in no line, just points

Question

please take a look at this:

http://jsfiddle.net/2rNzr/

var chart = new Highcharts.Chart({

    chart: {
        renderTo: 'container'
    },

    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },

    series: [{
        data: [29.9, '', 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]
    }]

});

you'll notice that the data has a blank value in it (the second value), which causes the line graph to display incorrectly.

Is this a bug?

What is the correct way of specifying a missing value so there will be a gap in the line graph? i.e. I would NOT want the line graph to simply draw a line between points 1 and 3.

Many thanks for producing an excellent product!

Tony.

Answer 1

You will need to change your missing values to null, and specify that you want a line/spline through the existing values.

var chart = new Highcharts.Chart({

    chart: {
        defaultSeriesType: 'line',
        renderTo: 'container'
    },

    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },

    series: [{
        data: [29.9, null, 106.4, 129.2, 144.0, 176.0, null, 148.5, 216.4, 194.1, 95.6, 54.4],
    }]

});

see http://jsfiddle.net/xynZT/ with defaultSeriesType: 'spline' as an example.

Answer 2

It's not displaying incorrectly its just plotting a scatter plot. I thinks this is because you don't have a complete series it will be treated like that. I possible, and this depends that your data doesn't use negative number, try to put the collection of no data a 0 such that you have data: [29.9, 0, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4] and this will display a line.