""" Read graphs in LEDA format. LEDA is a C++ class library for efficient data types and algorithms. Format ------ See http://www.algorithmic-solutions.info/leda_guide/graphs/leda_native_graph_fileformat.html """ # Original author: D. Eppstein, UC Irvine, August 12, 2003. # The original code at http://www.ics.uci.edu/~eppstein/PADS/ is public domain. __author__ = """Aric Hagberg (hagberg@lanl.gov)""" # Copyright (C) 2004-2019 by # Aric Hagberg # Dan Schult # Pieter Swart # All rights reserved. # BSD license. __all__ = ['read_leda', 'parse_leda'] import networkx as nx from networkx.exception import NetworkXError from networkx.utils import open_file, is_string_like @open_file(0, mode='rb') def read_leda(path, encoding='UTF-8'): """Read graph in LEDA format from path. Parameters ---------- path : file or string File or filename to read. Filenames ending in .gz or .bz2 will be uncompressed. Returns ------- G : NetworkX graph Examples -------- G=nx.read_leda('file.leda') References ---------- .. [1] http://www.algorithmic-solutions.info/leda_guide/graphs/leda_native_graph_fileformat.html """ lines = (line.decode(encoding) for line in path) G = parse_leda(lines) return G def parse_leda(lines): """Read graph in LEDA format from string or iterable. Parameters ---------- lines : string or iterable Data in LEDA format. Returns ------- G : NetworkX graph Examples -------- G=nx.parse_leda(string) References ---------- .. [1] http://www.algorithmic-solutions.info/leda_guide/graphs/leda_native_graph_fileformat.html """ if is_string_like(lines): lines = iter(lines.split('\n')) lines = iter([line.rstrip('\n') for line in lines if not (line.startswith('#') or line.startswith('\n') or line == '')]) for i in range(3): next(lines) # Graph du = int(next(lines)) # -1=directed, -2=undirected if du == -1: G = nx.DiGraph() else: G = nx.Graph() # Nodes n = int(next(lines)) # number of nodes node = {} for i in range(1, n + 1): # LEDA counts from 1 to n symbol = next(lines).rstrip().strip('|{}| ') if symbol == "": symbol = str(i) # use int if no label - could be trouble node[i] = symbol G.add_nodes_from([s for i, s in node.items()]) # Edges m = int(next(lines)) # number of edges for i in range(m): try: s, t, reversal, label = next(lines).split() except: raise NetworkXError('Too few fields in LEDA.GRAPH edge %d' % (i + 1)) # BEWARE: no handling of reversal edges G.add_edge(node[int(s)], node[int(t)], label=label[2:-2]) return G