.. _auto_curve_sign_change_stats:

*DETECT SIGN CHANGES AND RETURN THE STATS AROUND THAT POINT*
============================================================

Detects the first sign change (positive-to-negative or negative-to-positive) in a curve and returns descriptive statistics for the pre- and post-switch time windows around that transition point. Use this worker to characterise the magnitude, duration, and stability of a signal at the moment it crosses zero.

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

Classification: **process**.

Tagged: ``curve_analysis``, ``fluctuation``, ``sign_change``, ``signal``, ``statistics``, ``time_window``, ``zero_crossing``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve
     - curve
     - vector
     - —
     - 
     - Input curve (x/y vector) whose y-values are scanned for a sign change; must contain at least one crossing of zero.
   * - Switch Type
     - switchtype
     - list
     - positive_to_negative
     - 
     - Direction of the sign change to detect: 'positive_to_negative' (default) or 'negative_to_positive'; determines which zero-crossing event is targeted.
   * - Pre-switch Time Window
     - pre-switchtime_window
     - scalar
     - 600
     - 
     - Width of the analysis window before the detected crossing point (same units as the curve x-axis; default 600); sets the minimum duration over which the pre-switch state must persist to be considered a valid event.
   * - Post-switch Time Window
     - post-switchtime_window
     - scalar
     - 1200
     - 
     - Width of the analysis window after the detected crossing point (same units as the curve x-axis; default 1200); can be expressed as a percentage of the pre-switch window (e.g. '200%').
   * - Fluctuation Time Window
     - fluctuationtimewindowinpercentage
     - scalar
     - 2%
     - 
     - Tolerance window, expressed as a percentage of the pre-switch window size (default '2%'), within which minor y-value fluctuations around zero are ignored so that noisy crossings are not mis-detected.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curve_sign_change_stats_output_1
     - curve_sign_change_stats_output_1
     - dataset
     - Dataset containing descriptive statistics (e.g. mean, min, max, crossing time) computed over the pre- and post-switch windows surrounding the detected sign-change event.

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

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

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_sign_change_stats</code>. Schema hash: <code>5292235eae39</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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