<s> """<STR_LIT>""" <EOL> from heapq import heappush , heappop <EOL> from networkx import NetworkXError <EOL> import networkx as nx <EOL> __author__ = "<STR_LIT:\n>" . join ( [ "<STR_LIT>" , <EOL> "<STR_LIT>" ] ) <EOL> __all__ = [ '<STR_LIT>' , '<STR_LIT>' ] <EOL> def astar_path ( G , source , target , heuristic = None , weight = '<STR_LIT>' ) : <EOL> """<STR_LIT>""" <EOL> if G . is_multigraph ( ) : <EOL> raise NetworkXError ( "<STR_LIT>" ) <EOL> if heuristic is None : <EOL> def heuristic ( u , v ) : <EOL> return <NUM_LIT:0> <EOL> queue = [ ( <NUM_LIT:0> , hash ( source ) , source , <NUM_LIT:0> , None ) ] <EOL> enqueued = { } <EOL> explored = { } <EOL> while queue : <EOL> _ , __ , curnode , dist , parent = heappop ( queue ) <EOL> if curnode == target : <EOL> path = [ curnode ] <EOL> node = parent <EOL> while node is not None : <EOL> path . append ( node ) <EOL> node = explored [ node ] <EOL> path . reverse ( ) <EOL> return path <EOL> if curnode in explored : <EOL> continue <EOL> explored [ curnode ] = parent <EOL> for neighbor , w in G [ curnode ] . items ( ) : <EOL> if neighbor in explored : <EOL> continue <EOL> ncost = dist + w . get ( weight , <NUM_LIT:1> ) <EOL> if neighbor in enqueued : <EOL> qcost , h = enqueued [ neighbor ] <EOL> if qcost <= ncost : <EOL> continue <EOL> else : <EOL> h = heuristic ( neighbor , target ) <EOL> enqueued [ neighbor ] = ncost , h <EOL> heappush ( queue , ( ncost + h , hash ( neighbor ) , neighbor , <EOL> ncost , curnode ) ) <EOL> raise nx . NetworkXNoPath ( "<STR_LIT>" % ( source , target ) ) <EOL> def astar_path_length ( G , source , target , heuristic = None , weight = '<STR_LIT>' ) : <EOL> """<STR_LIT>""" <EOL> path = astar_path ( G , source , target , heuristic , weight ) <EOL> return sum ( G [ u ] [ v ] . get ( weight , <NUM_LIT:1> ) for u , v in zip ( path [ : - <NUM_LIT:1> ] , path [ <NUM_LIT:1> : ] ) ) </s>
