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Using the LoC Reconciliation Service with OpenRefine

This guide walks you through reconciling data in OpenRefine against Library of Congress authorities, matching strings in your project to controlled vocabulary terms and retrieving their labels and URIs.

Prerequisites

  • OpenRefine installed and running
  • A project open in OpenRefine with a column you want to reconcile

Step 1: Open the Reconciliation Dialog

  1. Click the arrow at the top of the column you want to reconcile
  2. Choose Reconcile → Start Reconciling...

Step 2: Add the LoC Reconciliation Service

  1. Click Add Standard Service in the bottom left corner of the dialog
  2. Enter the following URL: 
    https://reconcile.library.yorku.ca/loc/
  3. Click Add Service

The service will appear in the list as LC Reconciliation Service.

Step 3: Choose a Reconciliation Type

You will see a list of available vocabulary types. Use /LoC if you want to search LCNAF and LCSH together.

Step 4: Start Reconciling

Click Start Reconciling in the bottom right corner. OpenRefine will query the LoC Reconciliation Service for each cell in your column. This may take a moment depending on the size of your project.

Step 5: Review and Accept Matches

Once reconciliation is complete, each cell will display the closest matches found. For each cell:

  • Click on a candidate to open the corresponding authority page on id.loc.gov and verify it is the correct match
  • Click the single check (✓) beside a match to accept it for that cell only
  • Click the double check (✓✓) beside a match to accept it for all cells containing the same value

Repeat until you have accepted or dismissed matches for all cells.

Step 6: Save the Reconciled Data

Important

Although reconciled matches appear in your OpenRefine project, OpenRefine is still storing the original values internally. You must explicitly extract the reconciled data into a new column to ensure it is included when you export your project.

  1. Click the arrow at the top of the reconciled column
  2. Choose Edit Columns → Add column based on this column...
  3. Give the new column an appropriate name
  4. In the GREL expression box, enter one of the following depending on what you want to capture:
  5. Click OK

Useful GREL expressions

What you want GREL expression
Label only cell.recon.match.name
URI only cell.recon.match.id
Label and URI separated by | cell.recon.match.name + " \| " + cell.recon.match.id

Note

The label and URI combined option (separated by |) is useful if you want to split the column into two later, one for the label, and one for the URI.

Notes

  • If a cell shows no match, the reconciliation service found nothing close enough to suggest. You may want to check the spelling or try reconciling against a different vocabulary type.
  • If multiple candidates appear and none are correct, click the × to dismiss and leave the cell unmatched.
  • You can re-reconcile a column at any time by repeating this process.