Problem with group node


i have problem with group node: there is some bug in recognizing time date. 

When i'm grouping the data by days (in year) i find that it is not going correct. For example, days in column are showed like that: 1st Jan 2012, 2nd Jan 2012, 3rd Jan 2012, 3rd Jan, 5th Jan ...and etc. In some cells days are missing or repeating. I have noticed this error in new version of programm.

I have attached file  and i hope you'll help me to avoid and correct this mistake.

Thank you.


this is because the mean date operator computes the mean of dates based on their number of milliseconds since January 1, 1970 (Java standard representation). This might cause some rounding problems which result in the odd behavior. Attached you can find your workflow with additional nodes that demonstrate the mean computation. You might want to consider using the first aggregation operation instead of the mean operation.




That does look a bit funky.  I find it works as expected if you use the "First", "Set", or "List" aggregation methods so I think the problem is with how KNIME takes the mean of a set of timestamps.  I'll look into this further and post back here once I know more, but for now I would reccomed using a different aggregation method if possible.  



Thank you very much for the answer!