.. _auto_curve_has_zero_slope:

*DISCARD THE POINTS IF THE X-VALUE IS OUTSIDE OF THE RANGE SPECIFIED BELOW*
===========================================================================

Checks whether a curve has a zero (flat) slope by fitting a linear regression and evaluating both the R² goodness-of-fit and the fitted slope magnitude against configurable thresholds. Use this worker to automatically flag or filter curves that are effectively constant, such as plateaus in material test data or steady-state signals.

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

Classification: **process**.

Tagged: ``curve_check``, ``filter``, ``flat_line``, ``linear_fit``, ``r2``, ``slope_threshold``, ``zero_slope``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve to be checked
     - curvetobechecked
     - vector
     - —
     - 
     - The input curve (x/y vector) to be evaluated for zero slope; leave unconnected if used inline within a transformation chain.
   * - R2 value
     - r2_value
     - float
     - 0.9
     - 
     - Minimum R² threshold (0–1) for the linear fit to be considered valid; default is 0.9 — increase toward 1.0 for stricter linearity requirements.
   * - Slope threshold
     - slope_th
     - text
     - 0.001
     - 
     - Reference slope value (same units as dy/dx of the curve) against which the fitted slope is compared; the curve is deemed flat if the fitted slope is within 20% of this value — default is 0.001.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - Has zero Slope
     - has_zero_slope
     - scalar
     - Boolean scalar (1/true if the curve has a zero/flat slope, 0/false otherwise) based on the combined R² and slope-threshold criteria.

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

- data.curve.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=curve_has_zero_slope <https://www.d3view.com/api/workflow/example?id=curve_has_zero_slope>`_

.. raw:: html

   <hr style="margin-top:2em">
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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_has_zero_slope</code>. Schema hash: <code>4a3d416f18cb</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>