VhAfdZddlmZddlZgdZej ddddZej ddddd Zej dddd Z ej dddd Z ej dddd Z ej dddd Z ej ddddZ y)z@Basic algorithms for depth-first searching the nodes of a graph.) defaultdictN) dfs_edgesdfs_treedfs_predecessorsdfs_successorsdfs_preorder_nodesdfs_postorder_nodesdfs_labeled_edgessort_neighborsc#K|}n|g}| t} jnfd}t}|D]}||vr|j||||fg}d} |s)|d\} } | D]C} | |vs| | f|j| | |ks%|j | || f| dz } n|j | dz} |rhyw)aKIterate over edges in a depth-first-search (DFS). Perform a depth-first-search over the nodes of `G` and yield the edges in order. This may not generate all edges in `G` (see `~networkx.algorithms.traversal.edgedfs.edge_dfs`). Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search and yield edges in the component reachable from source. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Yields ------ edge: 2-tuple of nodes Yields edges resulting from the depth-first-search. Examples -------- >>> G = nx.path_graph(5) >>> list(nx.dfs_edges(G, source=0)) [(0, 1), (1, 2), (2, 3), (3, 4)] >>> list(nx.dfs_edges(G, source=0, depth_limit=2)) [(0, 1), (1, 2)] Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in PADS [1]_, with modifications to allow depth limits based on the Wikipedia article "Depth-limited search" [2]_. See Also -------- dfs_preorder_nodes dfs_postorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.edgedfs.edge_dfs` :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_edges` References ---------- .. [1] http://www.ics.uci.edu/~eppstein/PADS .. [2] https://en.wikipedia.org/wiki/Depth-limited_search NcDtj|SNiter neighborsnGr s `/home/dcms/DCMS/lib/python3.12/site-packages/networkx/algorithms/traversal/depth_first_search.pyzdfs_edges..ZtN1;;q>:;)lenrsetaddappendpop rsource depth_limitr nodes get_childrenvisitedstartstack depth_nowparentchildrenchilds ` ` rrrs x~!f   ! ; eG G   Ee,-. $Ry FH! ' %-'KK& ;. e\%-@%AB!Q   Q  sAC#C5C8C CT) returns_graphctj}||j|n|j||j t |||||S)a\Returns oriented tree constructed from a depth-first-search from source. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- T : NetworkX DiGraph An oriented tree Examples -------- >>> G = nx.path_graph(5) >>> T = nx.dfs_tree(G, source=0, depth_limit=2) >>> list(T.edges()) [(0, 1), (1, 2)] >>> T = nx.dfs_tree(G, source=0) >>> list(T.edges()) [(0, 1), (1, 2), (2, 3), (3, 4)] See Also -------- dfs_preorder_nodes dfs_postorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.edgedfs.edge_dfs` :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_tree` r )nxDiGraphadd_nodes_fromadd_nodeadd_edges_fromr)rr"r#r Ts rrrssMT A ~  6Yq&+nUV HrcTt||||Dcic]\}}|| c}}Scc}}w)aReturns dictionary of predecessors in depth-first-search from source. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search. Note that you will get predecessors for all nodes in the component containing `source`. This input only specifies where the DFS starts. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- pred: dict A dictionary with nodes as keys and predecessor nodes as values. Examples -------- >>> G = nx.path_graph(4) >>> nx.dfs_predecessors(G, source=0) {1: 0, 2: 1, 3: 2} >>> nx.dfs_predecessors(G, source=0, depth_limit=2) {1: 0, 2: 1} Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in `PADS`_, with modifications to allow depth limits based on the Wikipedia article "`Depth-limited search`_". .. _PADS: http://www.ics.uci.edu/~eppstein/PADS .. _Depth-limited search: https://en.wikipedia.org/wiki/Depth-limited_search See Also -------- dfs_preorder_nodes dfs_postorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.edgedfs.edge_dfs` :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_tree` r )r)rr"r#r sts rrrs8ta^T  Aq 1  s $ctt}t||||D]\}}||j|t |S)aReturns dictionary of successors in depth-first-search from source. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search. Note that you will get successors for all nodes in the component containing `source`. This input only specifies where the DFS starts. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- succ: dict A dictionary with nodes as keys and list of successor nodes as values. Examples -------- >>> G = nx.path_graph(5) >>> nx.dfs_successors(G, source=0) {0: [1], 1: [2], 2: [3], 3: [4]} >>> nx.dfs_successors(G, source=0, depth_limit=2) {0: [1], 1: [2]} Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in `PADS`_, with modifications to allow depth limits based on the Wikipedia article "`Depth-limited search`_". .. _PADS: http://www.ics.uci.edu/~eppstein/PADS .. _Depth-limited search: https://en.wikipedia.org/wiki/Depth-limited_search See Also -------- dfs_preorder_nodes dfs_postorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.edgedfs.edge_dfs` :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_tree` r"r#r )rlistrrdict)rr"r#r dr6r7s rrrsOp DA % 1 ! A  7NrcFtj||||}d|DS)aLGenerate nodes in a depth-first-search post-ordering starting at source. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- nodes: generator A generator of nodes in a depth-first-search post-ordering. Examples -------- >>> G = nx.path_graph(5) >>> list(nx.dfs_postorder_nodes(G, source=0)) [4, 3, 2, 1, 0] >>> list(nx.dfs_postorder_nodes(G, source=0, depth_limit=2)) [1, 0] Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in `PADS`_, with modifications to allow depth limits based on the Wikipedia article "`Depth-limited search`_". .. _PADS: http://www.ics.uci.edu/~eppstein/PADS .. _Depth-limited search: https://en.wikipedia.org/wiki/Depth-limited_search See Also -------- dfs_edges dfs_preorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.edgedfs.edge_dfs` :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_tree` r9c34K|]\}}}|dk(s |yw)reverseN.0uvr<s r z&dfs_postorder_nodes.._ 5'!Qa9nA 5r/r rr"r#r edgess rr r '+j   &k. E 6U 55rcFtj||||}d|DS)aPGenerate nodes in a depth-first-search pre-ordering starting at source. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search and return nodes in the component reachable from source. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- nodes: generator A generator of nodes in a depth-first-search pre-ordering. Examples -------- >>> G = nx.path_graph(5) >>> list(nx.dfs_preorder_nodes(G, source=0)) [0, 1, 2, 3, 4] >>> list(nx.dfs_preorder_nodes(G, source=0, depth_limit=2)) [0, 1, 2] Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in `PADS`_, with modifications to allow depth limits based on the Wikipedia article "`Depth-limited search`_". .. _PADS: http://www.ics.uci.edu/~eppstein/PADS .. _Depth-limited search: https://en.wikipedia.org/wiki/Depth-limited_search See Also -------- dfs_edges dfs_postorder_nodes dfs_labeled_edges :func:`~networkx.algorithms.traversal.breadth_first_search.bfs_edges` r9c34K|]\}}}|dk(s |yw)forwardNr@rAs rrEz%dfs_preorder_nodes..rFrGrHrIs rrrbrKrc #K|}n|g}| t} jnfd}t}|D]}||vr||df|j||||fg}d} |r|d\} } | D][} | |vr| | df| | df|j| | |kr)|j | t || f| dz } n-| | df]|j | dz} |r |dd| d f|r||d fyw) a Iterate over edges in a depth-first-search (DFS) labeled by type. Parameters ---------- G : NetworkX graph source : node, optional Specify starting node for depth-first search and return edges in the component reachable from source. depth_limit : int, optional (default=len(G)) Specify the maximum search depth. sort_neighbors : function (default=None) A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, `sorted` will sort the nodes in increasing order. Returns ------- edges: generator A generator of triples of the form (*u*, *v*, *d*), where (*u*, *v*) is the edge being explored in the depth-first search and *d* is one of the strings 'forward', 'nontree', 'reverse', or 'reverse-depth_limit'. A 'forward' edge is one in which *u* has been visited but *v* has not. A 'nontree' edge is one in which both *u* and *v* have been visited but the edge is not in the DFS tree. A 'reverse' edge is one in which both *u* and *v* have been visited and the edge is in the DFS tree. When the `depth_limit` is reached via a 'forward' edge, a 'reverse' edge is immediately generated rather than the subtree being explored. To indicate this flavor of 'reverse' edge, the string yielded is 'reverse-depth_limit'. Examples -------- The labels reveal the complete transcript of the depth-first search algorithm in more detail than, for example, :func:`dfs_edges`:: >>> from pprint import pprint >>> >>> G = nx.DiGraph([(0, 1), (1, 2), (2, 1)]) >>> pprint(list(nx.dfs_labeled_edges(G, source=0))) [(0, 0, 'forward'), (0, 1, 'forward'), (1, 2, 'forward'), (2, 1, 'nontree'), (1, 2, 'reverse'), (0, 1, 'reverse'), (0, 0, 'reverse')] Notes ----- If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched. The implementation of this function is adapted from David Eppstein's depth-first search function in `PADS`_, with modifications to allow depth limits based on the Wikipedia article "`Depth-limited search`_". .. _PADS: http://www.ics.uci.edu/~eppstein/PADS .. _Depth-limited search: https://en.wikipedia.org/wiki/Depth-limited_search See Also -------- dfs_edges dfs_preorder_nodes dfs_postorder_nodes NcDtj|Srrrs rrz#dfs_labeled_edges..rrrNrrnontreezreverse-depth_limitrr?)rrrrrrr r!s ` ` rr r scT~!f   ! ; eG& G  UI%% Ee,-. $Ry FH! :G# %22 %22KK& ;. eT,u2E-F%GH!Q $e-BBB : Q )A, 99%&UI%%5&s C3D8 D)NN)__doc__ collectionsrnetworkxr/__all__ _dispatchablerrrrr rr r@rrrWsF# ]$]]@%/ / &/ d:::z?t??D76D7676t7647676ts&$s&s&r