Sometimes Rule Engine, Variables and Null values can be tricky. I have added an example where you could define your own replacement rules. Age gets replaced by NULL and gender by “NA”.
Please note:
- there is no generic NULL in the Rule engine but ipazin came up with an clever solution (Create or replace column with NULL values) - create a column with just missing and use that
- you would always need a TRUE rule that covers everything else. If you do not have one you will create missing values
- you could deal with missing values later with the missing value node
The rules are defined in Excel and are then applied in a loop in KNIME
kn_example_replace_missings.knwf (47.1 KB)