Filter rows by matching substring

I’m new to knime because I’m trying to consolidate into one environment so I can stop bouncing back and forth between R and Python. I’m trying to merge data together from a dozen different data reports and I need a node that allows me to quickly filter rows by substring to see if a value exists so I can figure out why I’m end up with missing values after a series of joins.

For example,
If I have strings that look like: “*****ABCD”.

I need to filter a table down rows that match “ABCD”.

How do I set up a node to run a quick match on each data source to see if it’s really missing or if I have some more data cleaning to do?

I can’t seem to make any regex work in Knime, so I’m assuming there’s some syntax that I’m missing.
Is there a regex guide specific to Knime floating around out there?

Thanks for your time!

Welcome to the forum @norm762.

Can you share some actual strings and/or your workflow? It seems to me that any of the row filters should work.

The simplest one would be the Row Filter node with pattern matching selected and the expression *ABCD



1 Like

Hi @norm762 and welcome to the Knime Community.

Knime uses regular regex, so it would not have any regex guide specific to Knime.

May be you can share what you did and then we can see what the issue is.

Just be careful with the double escape backslashes. In Python this is better handled.

Got it thanks! I kept thinking an asterisk would be interpreted literally. It didn’t occur to me that’s what the checkbox for wildcards was referring to.

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