commit 37f2ac8da59cfeea02d9a6b2bd3892fa63d3cdd8
author root <root@localhost> Sat Mar 21 19:48:08 2015 +0100
committer root <root@localhost> Sat Mar 21 19:58:31 2015 +0100
tree 83527bb12986884a93d074a2dda01ba0a8210c2a
parent e447d44ca335fcbf4a8a73732e1527332c117643

Add a simple graphviz .dot output function

src/lib.rs

diff --git a/src/lib.rs b/src/lib.rs
index ac09b05..7674eec 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -28,6 +28,7 @@
 pub mod algo;
 pub mod graphmap;
 pub mod graph;
+pub mod parse;
 pub mod visit;
 
 pub mod unionfind;

src/parse.rs

diff --git a/src/parse.rs b/src/parse.rs
new file mode 100644
index 0000000..03d9b97
--- /dev/null
+++ b/src/parse.rs
@@ -0,0 +1,59 @@
+
+use std::fmt;
+use super::Graph;
+use super::EdgeType;
+use super::graph::IndexType;
+
+/// Wrapper implementing formatting to graphviz .dot format for a graph.
+#[derive(Copy, Clone, Debug)]
+pub struct DisplayDot<'a, G: 'a> {
+    graph: &'a G,
+}
+
+static TYPE: [&'static str; 2] = ["graph", "digraph"];
+static EDGE: [&'static str; 2] = ["--", "->"];
+static INDENT: &'static str = "    ";
+
+impl<'a, G> DisplayDot<'a, G>
+{
+    pub fn new(graph: &'a G) -> Self {
+        DisplayDot {
+            graph: graph,
+        }
+    }
+}
+
+impl<'a, N, E, Ty, Ix> fmt::Display for DisplayDot<'a, Graph<N, E, Ty, Ix>> where
+    N: fmt::Display,
+    E: fmt::Display,
+    Ty: EdgeType,
+    Ix: IndexType,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        let g = self.graph;
+        try!(writeln!(f, "{} {{", TYPE[g.is_directed() as usize]));
+
+        // output all labels
+        for (index, node) in g.raw_nodes().iter().enumerate() {
+            try!(writeln!(f, "{}N{} [label=\"{}\"]",
+                          INDENT, index, node.weight));
+
+        }
+        // output all edges
+        for edge in g.raw_edges().iter() {
+            try!(writeln!(f, "{}N{} {} N{} [label=\"{}\"]",
+                          INDENT,
+                          edge.source().index(),
+                          EDGE[g.is_directed() as usize],
+                          edge.target().index(),
+                          edge.weight));
+
+        }
+
+        // node name is "N%d"
+        try!(writeln!(f, "}}"));
+        Ok(())
+    }
+}
+

tests/ograph.rs

diff --git a/tests/ograph.rs b/tests/ograph.rs
index 8531504..1f0befa 100644
--- a/tests/ograph.rs
+++ b/tests/ograph.rs
@@ -14,6 +14,8 @@
     Undirected,
 };
 
+use petgraph::parse::DisplayDot;
+
 use petgraph::algo::{
     min_spanning_tree,
     is_cyclic_undirected,
@@ -83,6 +85,8 @@
     gr.add_edge(i, j, 1.);
     gr.add_edge(i, k, 2.);
 
+    println!("{}", DisplayDot::new(&gr));
+
     /*
     assert_eq!(DfsIter::new(&gr, h).count(), 4);
 
@@ -172,7 +176,10 @@
     gr.add_edge(h, j, 3.);
     gr.add_edge(i, j, 1.);
 
+    println!("{}", DisplayDot::new(&gr));
+
     let mst = min_spanning_tree(&gr);
+    println!("{}", DisplayDot::new(&mst));
     println!("MST is:\n{:?}", mst);
     assert!(mst.node_count() == gr.node_count());
     // |E| = |N| - 2  because there are two disconnected components.