Add general_simplicial_set_intersection to the uwot API

[jlmelville]

Add general_simplicial_set_intersection to the uwot API

[jlmelville]

@ratheraarif a few months ago at lmcinnes/umap#58 (comment) you asked for the ability to combine the fuzzy simplicial sets/graphs in R. The development version of uwot now has simplicial_set_intersect and simplicial_set_union to combine UMAP graphs, and follows the __mul__ and __add__ operators (but without doing any optimization of low dimensional coordinates).

It will appear in the next CRAN version if you don't want to install from github. Roughly, the R equivalent of the Python code you gave would be:

graph1 <- similarity_graph(X_reduced, n_neighbors = 93)
graph2 <- similarity_graph(Y_reduced, n_neighbors = 93)
intersection <- simplicial_set_intersect(graph1, graph2, weight = 0.45)

embedding <- optimize_graph_layout(intersection , X = X_reduced, min_dist = 1, init = "random", n_epochs = 1000)

You don't need to call reset_local_connectivity because the intersection/union operations do that for you. Note also that most of the initialization and optimization options that you provided in the UMAP constructor example have no effect on the result because the low dimensional output isn't used in the intersection.

[ratheraarif]

😊 Will surely give it a try. It was hard for me to go back and forth from Python to R for doing such analysis.

Thanks