javascript - Plotly: How to discard older points? -


tl;dr want display long-running strip chart plotly.js. don't know how discard old points.

details

the following updater codepen @ https://codepen.io/michael-f-ellis/pen/qvxpqr want. shows set of 20 samples in 2 traces update continuously @ 500 msec intervals. @ end of demo, plots points show still exist.

var cnt = 0; var interval = setinterval(function() {   // add next point each trace   plotly.extendtraces('graph', {     y: [[rand()], [rand()]]   }, [0, 1])   // display 20 recent points   plotly.relayout('graph', { 'xaxis.range': [cnt-20, cnt]})    cnt = cnt+1;   if(cnt === 100) {     // before ending run, show points     // demonstrate still exist in plotly.     plotly.relayout('graph', { 'xaxis.range': [0, cnt]});     clearinterval(interval);   } }, 500);

the problem do want delete older points. real application needs run forever on system limited memory. i'm looking plotly call drop oldest n trace points. needs reasonably efficient performance of target system limited.

thanks!

https://codepen.io/michael-f-ellis/pen/yxeewm

the above seems workable behavioral standpoint. here's revised updating routine:

plotly.plot('graph', data); var cnt = 0; var max = 20; var interval = setinterval(function() {   // add next point each trace   plotly.extendtraces('graph', {     y: [[rand()], [rand()]]   }, [0, 1])   // keep 'max' recent points   if(cnt > max) {     data[0].y.shift();     data[1].y.shift();   }   cnt = cnt+1;   if(cnt === 100) {     // before ending run, show points     // demonstrate 'max' points     // still exist in plotly.     plotly.relayout('graph', { 'xaxis.range': [0, cnt]});     clearinterval(interval);   } }, 500);

the solution keep data object in var outside of plotly , use shift() drop old points beginning of array new points added.

i'm open solution, if there known memory or performance problems approach.


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