.. _auto_dataset_uniquenum:

*COMPUTE THE UNIQUE NUMBER OF OCCURENCES IN VALUES*
===================================================

Counts the number of distinct values in a specified column of a dataset. Iterates over all rows, collects the values for the given column, and returns the count of unique entries. Use this worker to quickly audit cardinality or check for duplicate entries in any tabular dataset.

When to use
-----------

Classification: **process**.

Tagged: ``cardinality``, ``column``, ``count``, ``dataset``, ``deduplication``, ``distinct``, ``unique``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Response
     - response
     - keyvalue
     - —
     - 
     - Tabular dataset (key-value / row collection) whose column will be inspected for unique values; connect the upstream dataset output here.
   * - Column Name
     - column_name
     - scalar
     - —
     - 
     - Name of the column (string, quoted) within the dataset whose values will be deduplicated and counted; must match an existing column header exactly.

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - dataset_uniquenum_output_1
     - dataset_uniquenum_output_1
     - scalar
     - Scalar integer representing the number of distinct values found in the specified column of the input dataset.

Disciplines
-----------

- data.dataset.transform
- data.statistics

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=dataset_uniquenum <https://www.d3view.com/api/workflow/example?id=dataset_uniquenum>`_

.. raw:: html

   <hr style="margin-top:2em">
   <p style="font-size:11px;color:#888">
   Auto-generated from <code>transformation</code> schema. Worker id: <code>dataset_uniquenum</code>. Schema hash: <code>93c174d5c9bc</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>