Extract Information Using Regular Expressions

methodmethod Member Posts: 1 Contributor I
edited August 2019 in Help

I am following a tutorial from VancouverData on web crawling using RapidMiner.  

1.  Use CrawlWeb to load listings from Craigslist.org
2.  Use ProcessDocumentsFromFiles + Extract Information to create specific item fields

This is all working when I use XPath as the Extract Information query type.  However, when I change the query type to Regular Expression, I get errors.

Extract Information Settings:
query type: Regular Expression
attribute type: Nominal
regular expression queries (1):
attribute name: price
query expression: \$\d*

The error coming back is immediate:  "Process failed.  No group 1"

Any ideas on what I'm doing wrong here?


  • Options
    MultiMulti Member Posts: 4 Contributor I
    Yes, i had the same problem!
    Use surrounding brackets: (\$\d*) that should fix it. The Error is not helpful at all... ::)
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