  The pursuit of a comprehensive theory of gravity has led to the exploration
of various alternative models, necessitating a model-independent framework. The
Konoplya-Rezzolla-Zhidenko (KRZ) parameterization offers a robust method for
approximating stationary axisymmetric black hole spacetimes, characterized by a
rapidly converging continued-fraction expansion. However, while analytical
metrics benefit from this approach, numerical metrics derived from complex
gravitational theories remain presenting computational challenges. Bridging
this gap, we propose a method for a numerical KRZ parameterization, tested and
demonstrated on pseudo-numerical Kerr and Kerr-Sen spacetimes. Our approach
involves constructing numerical grids to represent metric coefficients and
using the grids for fitting the parameters up to an arbitrary order. We analyze
the accuracy of our method across different orders of approximation,
considering deviations in the metric functions and shadow images. In both Kerr
and Kerr-Sen cases, we observe rapid convergence of errors with increasing
orders of continued fractions, albeit with variations influenced by spin and
charge. Our results underscore the potential of the proposed algorithm for
parameterizing numerical metrics, offering a pathway for further investigations
across diverse gravity theories.
