Provide min and max distance to gr.co_occurence()

[MeyerBender]

Description

The computation of the co-occurrence gr.co_occurrence() currently automatically computes a min and max value (_find_min_max(spatial) in squidpy.gr._ppatterns). If I understand the code correctly, the minimum distance is computed by looking at the two cells with the lowest coordinate sums (x+y coordinate) and taking the Euclidean distance between the two. This method works fine as long as the cells fill out a rectangular image. However, it breaks when considering other shapes, such as TMA cores (see attached image).

In this specific case, the methodology returns a minimum threshold of 413 (see co-occurence plot), presumably due to some of the cells detected outside of the core (could also be a result of the core not being perfectly centered).

Naturally, I am interested in interactions below a distance of 400 as well. So, as a fix, I would propose to add a min_dist and max_dist parameter to gr.co_occurrence(), to give users full flexibility over the distance range they look at. The existing computation could still be used as a default.

[MeyerBender]

Nevermind, just found that this is already implemented with the interval keyword. Sorry for the confusion.