square grid to relationship graph for loom

gridgraph.clj

(defn gen-graph [s]
(graph ;;generate loom graph
  (reduce merge {} ;; format...
    (apply concat  ;; for loom
        (for [r (range s)] ;;for each row
          (for [c (range s)] ;;for each column in the row
            (let [nl [[r (+ 1 c)]
                      [(- r 1) c]
                      [r (- c 1)]
                      [(+ 1 r) c]]]
              {[r c]
               (let [res (for [n nl]
                           (->> n
                                (remove neg?) ;;out of bounds?
                                (remove #(> % (- s 1)))))] ;;out of bounds?
                 (remove #(< (count %) 2) res))}))))))) ;;remove all out of bounds

;;example shortest-path using this graph
(shortest-path (gen-graph 100) [0 3] [4 5]) ;; ([0 3] [1 3] [2 3] (3 3) [4 3] (4 4) [4 5])

for https://github.com/aysylu/loom

updated to a much faster version