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.TH TWOPI 1 "21 July 2001"
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twopi \- preprocessor for circular layouts of graphs
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\fBtwopi\fR [\fB\-G\fIname=value\fR]
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[\fB\-N\fIname=value\fR]
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[\fB\-o \fIoutfile\fR]
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draws graphs using a circular layout (see G. Wills,
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Symposium on Graph Drawing GD'97, September, 1997).
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Basically, one node is chosen as the center and put at the origin.
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The remaining nodes are placed on a sequence of concentric circles
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centered about the origin, each a fixed radial distance from the
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All nodes distance 1 from the center are placed on the first circle;
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all nodes distance 1 from a node on the first circle are placed on
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the second circle; and so forth.
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Input files must be formatted in the
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attributed graph language.
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By default, the output of
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is the input graph with layout coordinates appended.
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To make PostScript, use the \fB\-Tps\fP option.
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FrameMaker MIF (\fB-Tmif\fP), HPGL (\fB-Thpgl\fP),
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JPEG (\fB-Tjpeg\fP), SVG (\fB-Tsvg\fP),
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and GIF (\fB-Tgif\fP) are other choices.
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Here is a brief synopsis of the graph language.
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\fBgraph \fIname\fP { \fIstatement-list\fP }\fR is the top level graph.
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\fIname\fB=\fIval\fB;\fR
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\fBnode [\fIname\fB=\fIval\fB];\fR
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\fBedge [\fIname\fB=\fIval\fB];\fR
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Set the default graph, node, or edge attribute \fIname\fP to \fIval\fP.
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Any subgraph, node, or edge specified after one of these statements
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inherits these attributes.
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\fBn0 [\fIname0=val0,name1=val1,...\fB];\fR
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Creates node \fBn0\fP if it does not exist,
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and sets its attributes according to the optional list.
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\fBn0 \-\- n1 \-\- \fI...\fB \-\- nn [\fIname0=val0,name1=val1,...\fB];\fR
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Creates edges between nodes \fBn0\fP, \fBn1\fP, ..., \fBnn\fP and optionally
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sets the given attributes. Creates nodes as necessary.
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\fBsubgraph \fIname\fB { \fIstatement-list \fB}\fR
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Creates a subgraph. A subgraph may appear in place of
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an individual node within an edge statement.
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The \fBsubgraph \fIname\fR part is optional. If missing,
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the subgraph is given an internal name.
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While attribute names and values may be arbitrary strings,
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certain fixed attributes control \fItwopi\fP's layout algorithm,
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.SH "GRAPH ATTRIBUTES"
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Refer to \fIdot\fP(1) options to control the layout size.
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In addition, \fItwopi\fP recognizes the following:
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\fBcenter=\fIctr\fR. This specifies the node to be used as the center of
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the layout. If not specified, \fItwopi\fP will randomly pick one of the
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nodes that are furthest from a leaf node, where a leaf node is a node
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of degree 1. If no leaf nodes exists, an arbitrary node is picked as center.
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\fBranksep=\fIval\fR. Specifies the radial distance in inches between
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the sequence of rings. The default is 0.75.
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\fBoverlap=\fImode\fR. This specifies what \fItwopi\fP should do if
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any nodes overlap. If mode is \fI"false"\fP, the program uses Voronoi
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diagrams to adjust the nodes to eliminate overlaps. If mode is \fI"scale"\fP,
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the layout is uniformly scaled up, preserving node sizes, until nodes no
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longer overlap. The latter technique removes overlaps while preserving
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symmetry and structure, while the former removes overlaps more compactly
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but destroys symmetries.
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If mode is \fI"true"\fP (the default), no repositioning is done.
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\fBsplines=\fItrue/false\fR. If set to true, \fItwopi\fP will use the
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graphviz path planning library to draw edges as splines avoiding nodes.
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If the value is false, or some nodes overlap,
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edges are drawn as straight line segments connecting nodes.
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This is also the default style.
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Refer to \fIdot\fP(1) for options to control node labels, shapes,
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sizes, colors, fonts, etc.
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Refer to \fIdot\fP(1) for options to control edge line style and labels.
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.SH "COMMAND LINE OPTIONS"
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\fB\-v\fP (verbose) prints the center node and the rank separation.
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\fB\-V\fP (version) prints version information and exits.
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At present, the graph must be connected, with no
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Emden R. Gansner <erg@research.att.com>
added
removed
dotneato/twopi.1
