Trees (specially gb_trees) are a very efficient/fast tool to store Key-Value. However, depending on the program it’s usage cat get a bit more complicated. Here goes my challenge. What would be the most efficient way to get a random element and it’s path from a gb_tree?

The idea is good if we don’t want to cover the whole tree (just the k first), however to cover the whole tree, wouldn’t we have to execute rand:random() in each iteration (rand operations are quite expensive)?

So after thinking about it, my solution would be something like this: iex(1)> tree = :gb_tree.example() #Any f that returns a tree {3, {:a, 1, nil, {:b, 2, nil, {:c, 3, nil, nil}}}} iex(2)> n = :rand.uniform(:gb_trees.size(tree)) 2 iex(11)> iter = :gb_trees.iterator(tree) [{:a, 1, nil, {:b, 2, nil…

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al2o3cr September 24, 2020, 12:07pm 2

:gb_trees.iterator/1 plus a reservoir sampling algorithm?