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- Astropy v1.1.1 »
- Models and Fitting (`astropy.modeling`) »
- Identity

# Identity

class `astropy.modeling.mappings.``Identity`

  Bases: `astropy.modeling.mappings.Mapping`

  Returns inputs unchanged.

  This class is useful in compound models when some of the inputs must be passed unchanged to the next model.

  Parameters:

  n_inputs : int

  > Specifies the number of inputs this identity model accepts.

  name : str, optional

  > A human-friendly name associated with this model instance (particularly useful for identifying the individual components of a compound model).

  meta : dict-like

  > Free-form metadata to associate with this model.

  Examples

  Transform `(x, y)` by a shift in x, followed by scaling the two inputs:

      >>> from astropy.modeling.models import (Polynomial1D, Shift, Scale,
      ...                                      Identity)
      >>> model = (Shift(1) & Identity(1)) | Scale(1.2) & Scale(2)
      >>> model(1,1)
      (2.4, 2.0)
      >>> model.inverse(2.4, 2)
      (1.0, 1.0)