Feature request: trendoffset or trendrange
Opened this issue · 1 comments
olobarius commented
It would be nice to be able to do the trendline just for some part or range of the data.
In my case just for the last 10 elements. I did a quick hack and implemented a trendoffset parameter.
If > 0 it skips the first n elements, if < 0 it uses the last n elements.
The patch alters the firstIndex initialisation accordingly.
My code looks like this:
...
let fitter = new LineFitter();
// implement trendoffset paramater, alters firstIndex.
let trendoffset = dataset.trendlineLinear.trendoffset || 0;
if(Math.abs(trendoffset) >= dataset.data.length) trendoffset = 0;
let firstIndex = ((trendoffset<0)?dataset.data.length:0) + trendoffset + dataset.data.slice(trendoffset).findIndex((d) => {
return d !== undefined && d !== null;
});
let lastIndex = dataset.data.length - 1;
...
The config looks like this:
trendlineLinear: {
trendoffset: -10,
...
},
olobarius commented
I missed to post a modified line above. The forEach loop needs to skipp till firstIndex is reached, so it looks like this:
dataset.data.forEach((data, index) => {
if (data == null || index < firstIndex) return;