numbacs.extraction.elliptic
===========================

.. py:module:: numbacs.extraction.elliptic




Module Contents
---------------

.. py:function:: rotcohvrt(lavd, x, y, r, convexity_method='convex_hull', convexity_deficiency=0.005, min_val=-1.0, nlevs=20, start_level=0.0, end_level=0.0, min_len=0.0)

   Compute rotationally coherent vortices which are (approximately) convex closed
   contours of the lavd (or ivd) field.

   :param lavd: array containing lavd values.
   :type lavd: np.ndarray, shape = (nx,ny)
   :param x: array containing x-values.
   :type x: np.ndarray, shape = (nx,)
   :param y: array containing y-values.
   :type y: np.ndarray, shape = (ny,)
   :param r: radius in which points will be discared after a maximum is found at the center.
   :type r: float
   :param convexity_method: method used to determine if closed curve is convex, options are
                            'convex_hull' which calculates the relative difference in area of the curve and its
                            convex hull, 'angle' which checks if angle between succesive edges exceeds
                            convexity_deficiency in the negative direction. The default is 'convex_hull'.
   :type convexity_method: str, optional
   :param convexity_deficiency: value used to allow convexity deficiency up to this value, if 'convex_hull' method
                                is used this is the allowable relative difference in area, if 'angle' method is used
                                this is the allowable angle. The default is 5e-3.
   :type convexity_deficiency: float, optional
   :param min_val: minimum value allowed for maxima of the lavd field, if equals -1.0, the 80th percentile
                   of the lavd is used. The default is -1.0.
   :type min_val: float, optional
   :param nlevs: number of levels of contours to use when searching for convex curves. The default is 20.
   :type nlevs: int, optional
   :param start_level: starting level of contours for search, if equals 0.0 then the 70th percentile
                       of the lavd is used. The default is 0.0.
   :type start_level: float, optional
   :param end_level: value for last contour level to be checked, if equals 0.0 then the maximum of the lavd
                     is used. The default is 0.0.
   :type end_level: float, optional

   :returns: **rcv** -- list containing rotationally coherent vortices and corresponding vortex centers.
   :rtype: list