.. _fwflag_create_collocation_scores:
=============================
--create_collocation_scores
=============================
Switch
======

--create_collocation_scores [TABLE]

Description
===========

Creates a ``ufeat$...`` table from a feature table, annotated with PMI/NPMI collocation scores and percent-occurrence. Aliased as ``--create_collocs``. Meant to be used together with :doc:`fwflag_use_collocs` during n-gram extraction.

Argument and Default Value
==========================

An optional table name (``nargs='?', const=True``). If given with no value, defaults to the current :doc:`fwflag_t` table name.

Details
=======

**Known issue — broken in SQLite mode.** ``FeatureRefiner.creatCollocScores()`` itself uses the SQLite-aware ``QueryBuilder`` for table creation and the initial ``INSERT ... SELECT``, but then calls ``mysql_iter_funcs.extend_table()`` to add the ``pmi``/``pmi_filter_val``/``npmi``/``npmi_filter_val`` columns, which queries ``information_schema.COLUMNS`` — a MySQL/ANSI system view that doesn't exist in SQLite (which uses ``PRAGMA table_info`` instead). Verified: fails with repeated ``no such table: information_schema.COLUMNS`` retries, then exits with status 1 without adding the score columns. Works against MySQL.

Other Switches
==============

Required Switches:

* :doc:`fwflag_d`, :doc:`fwflag_c`, :doc:`fwflag_t`
* :doc:`fwflag_f`

Example Commands
================

Requires MySQL — broken against SQLite, see Known issue above:

.. code-block:: bash

	dlatkInterface.py -d dla_tutorial -t msgs -c user_id -f 'feat$1to3gram$msgs$user_id' --create_collocation_scores