.TH FDP 1 "1 April 2003"
.SH NAME
fdp \- filter for drawing undirected graphs
.SH SYNOPSIS
\fBfdp\fR [\fB\-G\fIname=value\fR]
[\fB\-N\fIname=value\fR]
[\-E\fIname=value\fR]
[\fB\-T\fIlang\fR]
[\fB\-l \fIlibfile\fR]
[\fB\-o \fIoutfile\fR]
[\fB\-v\fR]
[files]
.SH DESCRIPTION
.I fdp
draws undirected graphs using a ``spring'' model. It relies on a
force-directed approach in the spirit of Fruchterman and Reingold
(cf. Software-Practice & Experience 21(11), 1991, pp. 1129-1164).
Input files must be formatted in the
.I dot
attributed graph language.
By default, the output of
.I fdp
is the input graph with layout coordinates appended.
To make Postscript, use the \fB\-Tps\fP option.
FrameMaker MIF (\fB-Tmif\fP), HPGL (\fB-Thpgl\fP),
JPEG (\fB-Tjpg\fP and GIF (\fB-Tgif\fP) are other choices.
.PP
Here is a brief synopsis of the graph language.
.PP
\fBgraph \fIname\fP { \fIstatement-list\fP }\fR
.PP
declares a top level graph. Statements may be:
.PP
\fIname\fB=\fIval\fB;\fR
.br
\fBnode [\fIname\fB=\fIval\fB];\fR
.br
\fBedge [\fIname\fB=\fIval\fB];\fR
Set the default graph, node, or edge attribute \fIname\fP to \fIval\fP.
Any subgraph, node, or edge specified after one of these statements
inherits these attributes.
.PP
\fBn0 [\fIname0=val0,name1=val1,...\fB];\fR
Creates node \fBn0\fP if it does not exist,
and sets its attributes according to the optional list.
.PP
\fBn0 \-\- n1 \-\- \fI...\fB \-\- nn [\fIname0=val0,name1=val1,...\fB];\fR
Creates edges between nodes \fBn0\fP, \fBn1\fP, ..., \fBnn\fP and optionally
sets the given attributes. Creates nodes as necessary.
Although typically applied to undirected graph,
\fIfdp\fP will also layout directed graphs by simply ignoring
edge direction.
.PP
\fBsubgraph \fIname\fB { \fIstatement-list \fB}\fR
Creates a subgraph. A subgraph may appear in place of
an individual node within an edge statement.
The \fBsubgraph \fIname\fR part is optional. If missing,
the subgraph is given an internal name.
.PP
While attribute names and values may be arbitrary strings,
certain fixed attributes control \fIfdp\fP's layout algorithm.
Refer to \fIdot\fP(1) for general options for controlling layout
size, font faces and sizes, colors, labels, node shape, line styles, etc.
.SH "GRAPH ATTRIBUTES"
\fBK=\fIval\fR. Sets the default ideal node separation
in the layout.
.PP
\fBmaxiter=\fIval\fR. Sets the maximum number of iterations used to
layout the graph.
.PP
\fBstart=\fIval\fR. Adjusts the random initial placement of nodes
with no specified position. If \fIval\fP is is an integer,
it is used as the seed for the random number generator.
If \fIval\fP is not an integer, a random system-generated integer,
such as the process ID or current time, is used as the seed.
.PP
\fBsplines=\fIval\fR. If \fIval\fR is "true", edges are drawn
as splines to avoid nodes. By default, edges are draw as line segments.
.PP
.SH "NODE ATTRIBUTES"
\fBpin=\fIval\fR. If \fIval\fR is "true", the node will remain at
its initial position.
.SH "EDGE ATTRIBUTES"
\fBweight=\fIf\fR sets the weight of an edge
to the given floating point value. The default is 1.0;
greater values make the edge tend more toward its optimal length.
.PP
\fBlen=\fIf\fR sets the optimal length of an edge.
The default is \fBK\fP.
.SH "COMMAND LINE OPTIONS"
\fB\-v\fP (verbose) prints a log of the layout.
.PP
\fB\-V\fP prints the version and exits.
.PP
\fB\-?\fP prints the usage and exits.
.SH "SEE ALSO"
.BR dot (1),
.BR circo (1),
.BR neato (1),
.BR twopi (1)
.br