Positroids are a class of matroids in bijection with several combinatorial objects. In particular, every positroid can be constructed from a decorated permutation or from a Le-graph. In this paper, we present two algorithms, one that computes the rank of a subset of a positroid using its representation as a Le-graph and the other takes as input a decorated permutation σ and outputs the Le-graph that represent the same positroid as σ. These two algorithms combined form an improvement to Mcalmon and Oh’s result on the computation of the rank function of a positroid from the decorated permutation.