column expression

Hi all,

It’s always painful to obtain after a loop a column with no type or “Data Cell type”, in order to use this column you have to convert it previously to an identified type for example “string”. So you can use the string manipulation node and the string function (and it works), but if you try to to the same thing with the new “column expressions node”, you obtain the following error : No converter for column type ‘DataCell’ of column ‘ap+Append’ exists.

Workflow in attachmenttest_string.knwf (16.7 KB)


If I may add regarding Column Expressions node (which is great by the way) the average function says following:
Calculates the average. Missing values and NaNs are skipped.

I tried it with missing values and NaNs but it doesn’t work or I’m doing something wrong…

I used following syntax: average(column(col0),column(col1))



thanks for the feedback! Currently the Column Expressions Node only allows usages of columns for which converter exists. The problem in your example is, that the type is DataCell, which could be anything and that we don’t know how to convert it properly. I will check what we can do here.



I’m sorry, this is a bug, we will fix that. Thank you for your feedback!


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