Regular Expressions in Tableau

Regular Expressions (shortened as REGEX or REGEXP) is a sequence of characters that specifies a match pattern in a text. Usually, such patterns are used by string-searching algorithms for ‘find’ or ‘find and replace’ operations on strings or for input validation.

A basic example of regular expression would be regex /c*t/ which would match “cat”, “cot”, or “cut”, but not “pat” or “but”.

Tableau offers four REGEX functions which include.

• REGEXP_EXTRACT (string, pattern) – which extracts a text from a string field that matches the specified REGEX pattern.
• REGEXP_EXTRACT_NTH (string, pattern, index) – which is executed same as above, only that it extracts the nth matching group specified by the index.
• REGEXP_MATCH (string, pattern) – which returns TRUE if pattern is matched in the string field.
• REGEXP_REPLACE (string, pattern, replacement) – Which replaces the matched pattern with the specified replacement text.

In this short article, I will be sharing three use cases of regular expressions in Tableau.

Case 1: Extracting email addresses from a string of text.

The regular expression pattern for email addresses is,

To demonstrate this, I have connected the following text data which contains customer email addresses - the goal here is to demonstrate how you can use REGEX functionality to extract the email addresses.

To extract the email addresses from this text data, I will create the following calculation.

Note: The pattern in this calculation is enclosed in parentheses (capture group) - so Tableau can treat the multiple characters as a single unit.

Adding the calculation to the view.

(Which extracts each customer’s email address).

Case 2: Extracting a URL

The regular expression pattern for extracting URLs is,

Just like in the first case, you can extract URLs from text data using the following REGEX calculation.

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Note: The pattern in this calculation is enclosed in parentheses (capture group) - so Tableau can treat the multiple characters as a single unit.

Executing this calculation extracts the URLs from the text data.

Case 3: Extracting numbers from a string of text

Using Regular expressions, you can extract numbers from a string of text using the following calculation.

Note: The pattern in this calculation is enclosed in parentheses (capture group) - so Tableau can treat the multiple characters as a single unit.

Executing this calculation extracts the numbers from the text.

Conclusion

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