Problem with the One to Many node

KNIME Analytics Platform
#1

Hi everybody,
I have run into an unexpected error with the One to Many node (“column1 has no possible values” although it quite clearly has). I have attached a workflow showing the problem. I am stuck as to what causes the error (I’m running KNIME 3.6.0 on a 64 bit Windows machine)… I’d appreciate if somebody could point me towards a solution (the workflow also includes a workaround I’m using in the meantime but it’s slow).
Johannes

One to Many Problem Example.knwf (66.6 KB)

#2

Hi @johannes_clarifydata,

Can you try to use the Domain Calculator prior to the One To Many node? I guess the One to many node requires domain information on your nominal value.

Cheers,

Christian

1 Like
#3

Thanks @christian.dietz!

That solved the problem. However, it would be great if the error message could convey what you said more clearly (i.e. that there is a problem with the value domain). The magical number here seems to be 60 - columns with <= 60 unique values work fine with the One to Many node without using the Domain Calculator node prior to it.
I haven’t looked at the source code but it seems to me that the One to Many node is doing the domain calculation internally but is set to 60 values at maximum (which is also the default configuration of the Domain Calculator node)!? Hence, if there are more than 60 unique values the internal domain calculation causes a problem for the One to Many node.

Best wishes,
Johannes

#4

Thanks for the feedback. I’ll open a feature request to our dev-team for a better error message or make the node configurable or … :slight_smile:

Thanks again for the feedback.

#5

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