.. _auto_curves_match:

*COMPUTE THE DIFFERENCE BETWEEN TWO CURVES*
===========================================

Computes a scalar distance or difference metric between a baseline curve and a candidate curve. Supports a wide range of match types (RMSE, MAE, DTW, Fréchet, R², area, overlap, and more) with optional x-range clipping, synchronisation, normalisation, and outlier removal. Use this worker whenever a single numeric similarity or error score is needed to compare two time-history or XY curves.

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

Classification: **process**.

Tagged: ``comparison``, ``correlation``, ``curve_distance``, ``curve_match``, ``dtw``, ``frechet``, ``mae``, ``r2``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve Baseline
     - curve_baseline
     - vector
     - —
     - ✓
     - Reference (baseline) XY curve against which the candidate is measured; accepts a single curve or a multi-curve group — the first curve is used when a group is supplied.
   * - Curve Candidate
     - curve_candidate
     - vector
     - —
     - ✓
     - Candidate XY curve to be compared against the baseline; must share compatible x-axis units with the baseline.
   * - Curve Match Type
     - match_type
     - list
     - raw
     - 
     - Distance/difference metric to apply — choose from raw, abs, max, squared, RMSE, NRMSE, MAE, MAPE, MSE, R², area, Euclidean distance, Fréchet, DTW, PDTW, Space-Efficient DTW, overlap, ratio_ydiff, LCS, max-max-diff, critical_resultant, or min_derivative; default is 'euclidean-distance'.
   * - Digitize
     - digitize
     - list
     - 100
     - 
     - Digitize curves before curves match
   * - Normalize
     - normalize
     - list
     - no
     - 
     - Whether to normalise both curves (e.g., by their peak absolute value) before computing the metric; accepts 'yes' or 'no' (default 'no').
   * - Xmin
     - xmin
     - scalar
     - -100000000000000000000
     - 
     - Lower x-axis bound for clipping the comparison window; default is 0.0 (use start of curve).
   * - Xmax
     - xmax
     - scalar
     - 100000000000000000000
     - 
     - Upper x-axis bound for clipping the comparison window; default is 1e20 (use full extent of curve).
   * - Sync Curves
     - sync
     - list
     - yes
     - 
     - Whether to re-sample and synchronise the two curves to a common x-grid before matching; accepts 'yes' (default) or 'no'.
   * - Enforce Monotonicity
     - skip_drop
     - list
     - no
     - 
     - Whether to skip sudden drops in the candidate curve when computing the metric; accepts 'yes' or 'no' (default 'no').
   * - Diff Ratio Threshold
     - diff_ratio_threshold
     - scalar
     - 0.1
     - 
     - Only applies if the diff type is ratio based
   * - Remove Outlier Points
     - remove_outliers
     - list
     - no
     - 
     - Whether to remove statistical outliers from the difference signal before computing the final metric; accepts 'yes' (default) or 'no'.
   * - Distance Measurement Type
     - distance_measurement_type
     - list
     - euclidean
     - 
     - Only applied for Frechet, DTW, pDTW
   * - Scale By Area Diff
     - scale_by_area_diff
     - select
     - no
     - 
     - Whether to scale the resulting metric by the area difference between the two curves; accepts 'yes' or 'no' (default 'no').
   * - Clip Method
     - clip_method
     - list
     - old
     - 
     - Algorithm variant used for x-range clipping; accepts 'old' (default, legacy behaviour) or 'new' (updated clipping logic).

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curves_match_output_1
     - curves_match_output_1
     - scalar
     - Scalar numeric value representing the computed distance or error metric between the baseline and candidate curves, in the units implied by the chosen match_type (e.g., dimensionless for R² and NRMSE, same units as y-axis for MAE/RMSE, or curve units² for MSE).

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

- data.correlation
- data.curve.pair
- data.statistics

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

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

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curves_match</code>. Schema hash: <code>89aa55f4b4e1</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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