This is the RefinePro knowledge base about OpenRefine. We build it over the years, and keep adding to it. From great tutorials and how-to, to handy GREL expressions and links to external resources, you will find here one of the most comprehensive list of resources to learn OpenRefine.

For a comprehensive documentation you should refer to the official OpenRefine wiki.

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remove " (quotation) mark

Hard time removing the " (quote sign) from your expression. Instead of quoting your quote mark with double quote, do it with simple like this :


Remove or replace a specific character in a column

You want to remove a space or a specific character from your column like the sign # before some number.


merge 2 columns that have both blank cells

New - March 2020 Update:

  • OpenRefine 3.0, we have the coalesce() function:  which natively handles the null correctly. 
  • OpenRefine 3.3 introduced a user interface that offers tons of flexibility. See tutorial

The basic function to merge or concatenate data from two different column is the following:
cells["col1"].value + " " + cells["col2"].value


    Add a space to postal code (splitByLength and Merge function)

    This short tips explains how to convert postal code store on 6 characters to 7 by adding a space after 3 digits. We will use splitByLength (see related video) and merge multiple column into one functions.


    Compare values from two columns

    To compare strings from 2 differents column and present the results in a third one, use the following expression:


    Move data from a column to an other

    Some data are messy and column can be a mix of different type of data. For example if you work on an address database, you might have a ZIP code column and a State column. And some ZIP code can be stored in the State Column.


    Faceting with Freebase Gridworks

    Freebase is the name of google refine before google took control of the solution. The two following videos present how to facet (filter) in google refine. The interface and options did not evolve too much over the time and version making those videos still up to date.