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.

  • 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

  • inverse (bool, optional) – If set to True, it performs the inverse transform. False by default.

  • 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.


  • R (array-like) – Array of any shape containing the (back-)transformed units.

  • metadata (dict) – The metadata with updated attributes.


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,, 2012.