highslide-software/highcharts.com — Issue #718: Data grouping interval does not take irregular data into account
Author: highslide-software
Created: 2012-01-23 14:21:25+00:00
State: open

1. Open http://jsfiddle.net/highcharts/PWjce/. This example has 24h data, then one single point is added 1h after the last point.
2. Click "All". Observe that the data is now grouped into 6h intervals, even though each interval represents less than 1 pixel.
3. Remove the code block where the additional point is added, then Run and click All. Observe that the same data is now grouped into weeks.

The reason behind this is that when the grouping interval is computed, Highcharts divides the data range by the imagined plot width. The imagined plot width is an estimation of how wide the plot area would be without ordinal logic, based on the closest point range. This imagined plot width needs to take into account all the distances between ordinal positions, not only the closest point range.