You are correct: trendlines only work for continuous-axis charts, as you
can't create a function f(x) when x is a string (solve f(x) = 3x + 5 where
x = "foo" does not compute). You can fake it, however, with a bit of
clever trickery using a DataView and the hAxis.ticks option:
var view = new google.visualization.DataView(data);
view.setColumns([{
type: 'number',
label: data.getColumnLabel(0),
calc: function (dt, row) {
return {v: row, f: data.getValue(row, 0)};
}
}, 1 /*, 2, 3... however many data series you have */]);
var hAxisLabels = [];
for (var i = 0; i < data.getNumberOfRows(); i++) {
hAxisLabels.push({v: i, f: data.getValue(i, 0)});
}
chart.draw(view, {
// options
hAxis: {
ticks: hAxisLabels
}
}
see example here: http://jsfiddle.net/asgallant/yYuu7/
On Monday, January 6, 2014 8:49:17 AM UTC-5, Michael Falkson wrote:
>
> Trendlines seems to only work when the first column is numeric.
>
> I have a combo chart ...
>
> Columns - Months (string), HoursWorked(number/BAR),PerHour(number/LINE).
>
> I need to add a trend line on the 2rd column/series.
>
> Here is what I did (but it's not working)
>
> trendlines: {
>
> 1: {
>
> type: ''linear'',
>
> color: ''red'',
>
> labelInLegend: ''Trend'',
>
> visibleInLegend: true,
>
> }
> Any help would be appreciated.
>
> Mike
>
>
>
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