pysteps.utils.transformation.NQ_transform¶

pysteps.utils.transformation.NQ_transform(R, metadata=None, inverse=False, **kwargs)¶

The normal quantile transformation as in Bogner et al (2012). Zero rain vales are set to zero in norm space.

Parameters

R: array-like: Array of any shape to be transformed.
metadata: dict, optional: Metadata dictionary containing the transform, zerovalue and threshold attributes as described in the documentation of pysteps.io.importers.
inverse: bool, optional: If set to True, it performs the inverse transform. False by default.

Returns

R: array-like: Array of any shape containing the (back-)transformed units.
metadata: dict: The metadata with updated attributes.

Other Parameters

a: float, optional: The offset fraction to be used for plotting positions; typically in (0,1). The default is 0., that is, it spaces the points evenly in the uniform distribution.

References

Bogner, K., Pappenberger, F., and Cloke, H. L.: Technical Note: The normal quantile transformation and its application in a flood forecasting system, Hydrol. Earth Syst. Sci., 16, 1085-1094, https://doi.org/10.5194/hess-16-1085-2012, 2012.