Hi, I need help regarding the rule engine, is it possible to have output a combination of Col-Value and String (or another Col-Value) For example, following given an error, TRUE => $Col 1$ + $Col 2$ TRUE => $Col 1$ + “ABC” Thanks.

Hi @nikola_tesla , The Column Expression should be used in this case, as suggested by @aworker . Rule Engine does not allow operations, only conditions. You can apply conditions, but your results should be either values from an existing column or variable, or hardcoded values, basically “pre-compiled” values. Also, you can’t have 2 TRUE statements. Well, I don’t know if Knime allows you to, but it’s irrelevant, as even if it did, only the first TRUE statement will be true - the way Rule Engine works is it evaluates your statements in the order you have written them, and as soon as a line is true, then that’s the chosen rule and it stops evaluating the rest of the lines. With Math Formula (and with String Manipulation), it’s the opposite. It allows you to do operations (and manipulation), but you can’t apply conditions (though there are a few tricks where you can indirectly apply some limited conditions). The Column Expression (and the Variable Expression) allows you to do both: Apply condition and do operations/manipulation.

Help required regarding rule engine

KNIME Analytics Platform

aworker March 16, 2022, 10:55am 6

Hi @nikola_tesla

Please have a look at the following thread which looks very similar to your problem. You will find your solution from @bruno29a’s last post based on the -Column Expression- node.

Best

Ael

1 Like