netsse.analys.spec.spec2d_to_params
===================================

.. py:function:: netsse.analys.spec.spec2d_to_params(S2D, freq, theta, unit_theta='deg', smooth_peak=False)

   Computes a set of overall parameters characterizing the sea state from the
   2-D wave spectrum.

   :param S2D: Directional wave spectrum [m^2.s/``unit_theta``], as a function of frequency
               in Hertz and wave direction in specified unit (``unit_theta``).
   :type S2D: array_like of shape (...,Nf,Ntheta,...)
   :param freq: Vector of (discretized) wave frequencies [Hz] (must include :math:`f =` 0 Hz).
   :type freq: array_like of shape (Nf,)
   :param theta: Vector of wave headings [the unit is specified in ``unit_theta``].

                 .. attention::
                     ``theta`` must be in a wrapped format, i.e., corresponding to [0,360] deg.
   :type theta: array_like of shape (Ntheta,)
   :param unit_theta: Unit of the wave directions. This applies for the expression of the wave
                      spectrum too. Can be ``'deg'`` (for degrees), or ``'rad'`` (for radians).
                      ``'deg'`` is the default.
   :type unit_theta: {'deg','rad'}, optional
   :param smooth_peak: Specify whether the output ``Tp`` and ``theta_p`` values should be smoothened by
                       fitting a polynomial of order 3 in the vicinity of the spectral peak and
                       estimating the peak period and direction through the fitted polynomial.
                       The default is ``False``.
   :type smooth_peak: bool, optional

   :returns: * **m** (*array_like of shape (6,)*) -- Spectral moments :math:`[m_{-1},m_0,m_1,m_2,m_3,m_4]`.
             * **Hm0** (*float, or array_like*) -- Spectral significant wave height [m].
             * **Tp** (*float, or array_like*) -- Peak wave period [s].
             * **Tm01** (*float, or array_like*) -- Mean wave period [s].
             * **Tm02** (*float, or array_like*) -- Zero up-crossing period [s].
             * **Tm24** (*float, or array_like*) -- Mean crest period [s].
             * **TE** (*float, or array_like*) -- Mean energy period [s].
             * **Sm02** (*float, or array_like*) -- Significant wave steepness [-].
             * **epsilon** (*float, or array_like*) -- Spectral bandwidth [-].
             * **Qp** (*float, or array_like*) -- Goda's peakedness parameter [-].
             * **theta_p** (*float, or array_like*) -- Peak wave direction [deg].
             * **theta_m** (*float, or array_like*) -- Mean overall wave direction [deg].
             * **sigma_m** (*float, or array_like*) -- Mean directional spreading [deg].

   .. seealso::

      :obj:`spec1d_to_params`
          Computes the main sea state parameters from a given 1-D wave spectrum.

   .. rubric:: Example

   >>> m, Hm0, Tp, Tm01, Tm02, Tm24, TE, Sm02, epsilon, Qp, theta_p, theta_m, sigma_m =
   ...     spec2d_to_params(S2D,freq,theta,unit_theta='deg',smooth_Tp=False)