Regular Expression Engine

[TardisPilot]

Hey All!

I can get regular expressions to work in KNIME most of the time but I have a big issue I am trying to solve. For whatever KNIME will not capture the ‘@’ in the RexEx matcher.

I type something like this [A-Za-z0-9]+@ and it can’t find the @. What am I doing wrong?

Also, what engine is KNIME using for regular expression syntax?

[armingrudd]

Hi,

Would you please provide an example of the string you want to match with this regex pattern?

[TardisPilot]

Hi @armingrudd,

I would like some degree of email matching to a part of a larger expression for a project and it seems that Regex Matcher won’t match special characters.

edit: I would also like to be able to match on @$%& etc. But can’t get KNIME to match on any of those.

abc123@.com
aaabbbccc@.org

[armingrudd]

@TardisPilot

Regex Matcher won’t match special characters.

Of course it does. You have to match the whole string not just a part of it.
For example to match emails like “abc123@abc123.com”, you have to use this regex:

regexMatcher($column1$, "[A-Za-z0-9]+@[A-Za-z0-9]+\\.[a-zA-Z]{2,3}")

[TardisPilot]

@armingrudd,

Thank you, that makes sense. I guess I was hoping I could write the expression slightly differently by just having a group followed by a special character. I’m not even concerned about the .com part

[armingrudd]

What do you mean by differently?
There are so many patterns you can use to match this format.
Let me know what you were trying to do and I will help you with that.

[TardisPilot]

Thank you! I just want to find A-Za-z0-9 followed by an @ sign or $ or &.etc.

[armingrudd]

Then use this:
regexMatcher($column1$, "[A-Za-z0-9]+[@$&!#%]")

This will match any string starting with some text and numbers followed by one of the special characters I have added.

If it can be followed by anything after the special character, then add the .* after the last brackets.

Is that clear?

[TardisPilot]

@armingrudd,

Got it! Thank you!