# HG changeset patch
# User Balazs Dezso <deba@inf.elte.hu>
# Date 1215694955 -7200
# Node ID 9757e3d9bfebfbe7af6f4a9d8d7741e4ce8f1c4e
# Parent e80e08222fdf7808460dffd57a003b595d0098da
More docs for undirected LGF IO
diff -r e80e08222fdf -r 9757e3d9bfeb doc/lgf.dox
--- a/doc/lgf.dox Wed Jul 09 07:57:53 2008 +0200
+++ b/doc/lgf.dox Thu Jul 10 15:02:35 2008 +0200
@@ -78,10 +78,18 @@
2 3 18
\endcode
-The \c \@edges is just a synonym of \c \@arcs.
+The \c \@edges is just a synonym of \c \@arcs. The @arcs section can
+also store the edge set of an undirected graph. In such case there is
+a conventional method for store arc maps in the file, if two columns
+has the same caption with \c '+' and \c '-' prefix, then these columns
+can be regarded as the values of an arc map.
The \c \@attributes section contains key-value pairs, each line
-consists of two tokens, an attribute name, and then an attribute value.
+consists of two tokens, an attribute name, and then an attribute
+value. The value of the attribute could be also a label value of a
+node or an edge, or even an edge label prefixed with \c '+' or \c '-',
+which regards to the forward or backward directed arc of the
+corresponding edge.
\code
@attributes
diff -r e80e08222fdf -r 9757e3d9bfeb lemon/lgf_reader.h
--- a/lemon/lgf_reader.h Wed Jul 09 07:57:53 2008 +0200
+++ b/lemon/lgf_reader.h Thu Jul 10 15:02:35 2008 +0200
@@ -1226,6 +1226,12 @@
/// It can be used almost the same way as \c DigraphReader.
/// The only difference is that this class can handle edges and
/// edge maps as well as arcs and arc maps.
+ ///
+ /// The columns in the \c \@edges (or \c \@arcs) section are the
+ /// edge maps. However, if there are two maps with the same name
+ /// prefixed with \c '+' and \c '-', then these can be read into an
+ /// arc map. Similarly, an attribute can be read into an arc, if
+ /// it's value is an edge label prefixed with \c '+' or \c '-'.
template <typename _Graph>
class GraphReader {
public:
diff -r e80e08222fdf -r 9757e3d9bfeb lemon/lgf_writer.h
--- a/lemon/lgf_writer.h Wed Jul 09 07:57:53 2008 +0200
+++ b/lemon/lgf_writer.h Thu Jul 10 15:02:35 2008 +0200
@@ -914,6 +914,12 @@
/// It can be used almost the same way as \c DigraphWriter.
/// The only difference is that this class can handle edges and
/// edge maps as well as arcs and arc maps.
+ ///
+ /// The arc maps are written into the file as two columns, the
+ /// caption of the columns are the name of the map prefixed with \c
+ /// '+' and \c '-'. The arcs are written into the \c \@attributes
+ /// section as a \c '+' or a \c '-' prefix (depends on the direction
+ /// of the arc) and the label of corresponding edge.
template <typename _Graph>
class GraphWriter {
public: