Netlogo中的NW扩展

我试图运行这个模型，但是它并没有启动，我不明白“nw”扩展名有什么问题。 我安装了netlogo 5.2.1和已经捆绑的“nw”扩展。 Netlogo在第48行显示错误（nw：快照节点链接）。 错误消息是“没有名为NW：SET-SNAPSHOT已定义”。 请帮忙。 整个代码是

extensions [gis nw table array] breed [leavers leaver] breed [followers follower] breed [officers officer ] breed [ nodes node ] turtles-own [voisins] leavers-own [ cur-link speed path-end current start to-node from-node origin destin] globals [network walls itc itc-dataset walls-dataset officer_walkspeed leaver_walkspeed follower_walkspeed interaction_time person_size max_preevacuation_delay loaded ticks_per_sec arr-e v path1 next-node distance100 distance200] undirected-link-breed [ friendships friendship ] to startup ;; called when first loaded read-gis-datasets end to setup clear-all-but-globals ;; don't loose datasets ask patches [set pcolor white] setup-world-envelope draw-world setup-paths-graph ask nodes [setxy xcor ycor if show_names? = True [show-names]] setup-leavers end to clear-all-but-globals reset-ticks ct cp cd clear-links clear-all-plots clear-output end to read-gis-datasets ;set walls gis:load-dataset "walls.shp" set network gis:load-dataset "BRT.shp" ;set itc gis:load-dataset "itc.shp" end to setup-world-envelope let world ( gis:envelope-of network ) ;; [ minimum-x maximum-x minimum-y maximum-y ] gis:set-world-envelope (world) end to setup-paths-graph set-default-shape nodes "circle" foreach polylines-of network 3 [ (foreach butlast ? butfirst ? [ if ?1 != ?2 [ ;; skip nodes on top of each other due to rounding let n1 new-node-at first ?1 last ?1 let n2 new-node-at first ?2 last ?2 ask n1 [create-link-with n2] ]]) ] ask nodes [hide-turtle] nw:set-snapshot nodes links end to-report polylines-of [dataset decimalplaces] let polylines gis:feature-list-of dataset ;; start with a features list set polylines map [first ?] map [gis:vertex-lists-of ?] polylines ;; convert to virtex lists set polylines map [map [gis:location-of ?] ?] polylines ;; convert to netlogo float coords. set polylines remove [] map [remove [] ?] polylines ;; remove empty poly-sets .. not visible set polylines map [map [map [precision ? decimalplaces] ?] ?] polylines ;; round to decimalplaces ;; note: probably should break polylines with empty coord pairs in the middle of the polyline report polylines ;; Note: polylines with a few off-world points simply skip them. end to-report new-node-at [xy] ; returns a node at x,y creating one if there isn't one there. let n nodes with [xcor = x and ycor = y] ifelse any? n [set n one-of n] [create-nodes 1 [setxy xy set size 2 set n self]] report n end to show-names ifelse label = "" [set label (word who " ")] [set label ""] end to draw-world gis:set-drawing-color [255 0 0] gis:draw network 1 end to setup-leavers set-default-shape leavers "person" set leaver_walkspeed 1 create-leavers num-leaver [ set size 1 set origin one-of nodes if origin = 100 or origin = 200 [show origin set origin one-of nodes] move-to origin show origin ask origin [set distance100 nw:distance-to node 110] ask origin [set distance200 nw:distance-to node 210] ifelse distance100 > distance200 [ask origin [set path1 nw:turtles-on-path-to node 210]] [ask origin [set path1 nw:turtles-on-path-to node 110]] ;[set destin node 200] ;[set destin node 100] let a array:from-list path1 set destin array:item a 1 ] end to go tick ask leavers [ if distance destin < 0.01 ;; round off error fix [ set origin destin move-to origin ask origin [set distance100 nw:distance-to node 110] ask origin [set distance200 nw:distance-to node 210] ifelse distance100 > distance200 [ask origin [set path1 nw:turtles-on-path-to node 210]] [ask origin [set path1 nw:turtles-on-path-to node 110]] ;[set destin node 200] let a array:from-list path1 if array:length a > 1 [set destin array:item a 1 ] ;origin array:item a 1 ;set next-node one-of [link-neighbors] of to-node face to-node destin] ] ] face destin fd 0.01 ] end to create-shortest-path ask nodes [set color green] if Origin = Destin [user-message "Please select two different nodes" stop] ask node Origin [set color blue] ask node Destin [set color blue] ;ask node origin [ show nw:path-to node Destin] ask node origin [ show nw:turtles-on-path-to node destin ] output-show [ nw:distance-to node destin ] of node origin ;=> 1 end