Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/networkx/readwrite/p2g.py

@@ -0,0 +1,102 @@
+"""
+This module provides the following: read and write of p2g format
+used in metabolic pathway studies.
+
+See https://web.archive.org/web/20080626113807/http://www.cs.purdue.edu/homes/koyuturk/pathway/ for a description.
+
+The summary is included here:
+
+A file that describes a uniquely labeled graph (with extension ".gr")
+format looks like the following:
+
+
+name
+3 4
+a
+1 2
+b
+
+c
+0 2
+
+"name" is simply a description of what the graph corresponds to. The
+second line displays the number of nodes and number of edges,
+respectively. This sample graph contains three nodes labeled "a", "b",
+and "c". The rest of the graph contains two lines for each node. The
+first line for a node contains the node label. After the declaration
+of the node label, the out-edges of that node in the graph are
+provided. For instance, "a" is linked to nodes 1 and 2, which are
+labeled "b" and "c", while the node labeled "b" has no outgoing
+edges. Observe that node labeled "c" has an outgoing edge to
+itself. Indeed, self-loops are allowed. Node index starts from 0.
+
+"""
+import networkx
+from networkx.utils import open_file
+
+
+@open_file(1, mode="w")
+def write_p2g(G, path, encoding="utf-8"):
+    """Write NetworkX graph in p2g format.
+
+    Notes
+    -----
+    This format is meant to be used with directed graphs with
+    possible self loops.
+    """
+    path.write((f"{G.name}\n").encode(encoding))
+    path.write((f"{G.order()} {G.size()}\n").encode(encoding))
+    nodes = list(G)
+    # make dictionary mapping nodes to integers
+    nodenumber = dict(zip(nodes, range(len(nodes))))
+    for n in nodes:
+        path.write((f"{n}\n").encode(encoding))
+        for nbr in G.neighbors(n):
+            path.write((f"{nodenumber[nbr]} ").encode(encoding))
+        path.write("\n".encode(encoding))
+
+
+@open_file(0, mode="r")
+def read_p2g(path, encoding="utf-8"):
+    """Read graph in p2g format from path.
+
+    Returns
+    -------
+    MultiDiGraph
+
+    Notes
+    -----
+    If you want a DiGraph (with no self loops allowed and no edge data)
+    use D=networkx.DiGraph(read_p2g(path))
+    """
+    lines = (line.decode(encoding) for line in path)
+    G = parse_p2g(lines)
+    return G
+
+
+def parse_p2g(lines):
+    """Parse p2g format graph from string or iterable.
+
+    Returns
+    -------
+    MultiDiGraph
+    """
+    description = next(lines).strip()
+    # are multiedges (parallel edges) allowed?
+    G = networkx.MultiDiGraph(name=description, selfloops=True)
+    nnodes, nedges = map(int, next(lines).split())
+    nodelabel = {}
+    nbrs = {}
+    # loop over the nodes keeping track of node labels and out neighbors
+    # defer adding edges until all node labels are known
+    for i in range(nnodes):
+        n = next(lines).strip()
+        nodelabel[i] = n
+        G.add_node(n)
+        nbrs[n] = map(int, next(lines).split())
+    # now we know all of the node labels so we can add the edges
+    # with the correct labels
+    for n in G:
+        for nbr in nbrs[n]:
+            G.add_edge(n, nodelabel[nbr])
+    return G