I want to keep all rows that have e.g. empty cells in column x. I tried this with a row filter node and an regular expression like ^$, but that does not work.
I do not know why? Can anyone explain this?
To generate missing value is not an option, because the input table was generated via a cell splitter node and this node cannot generate missing values for empty cells.
A workaround is to use a java row filter with return $column_x$.equals("");