Drawing graphs with dot
Contents
1. Architecture amp Libraries dot User s Manual November 20 1996 12 cron Drawing graphs with dot m j 12 13 14 15 16 17 18 19 20 OANDOBPWN HE a fo digraph g node shape node0 label nodei label node2 label node3 label node4 label node5 label node6 label node7 label node8 label node0 f2 node0 f0 nodei f0 nodei f2 node2 f2 node2 f0 node4 f2 node4 f0 record height 1 lt f0 gt lt f1 gt GI lt f2 gt J lt f0 gt lt f1 gt E lt f2 gt lt f0 gt lt f1 gt BI lt f2 gt lt f0 gt lt f1 gt F lt f2 gt lt f0 gt lt f1 gt RI lt f2 gt J lt f0 gt lt f1 gt H lt f2 gt lt f0 gt lt f1 gt Y lt f2 gt lt f0 gt lt f1 gt Al lt f2 gt lt f0 gt lt f1 gt C lt f2 gt J node4 f1 nodei f1 node2 f1 node3 f1 node8 f1 node7 f1 node6 f1 node5 f1 Figure 9 Binary search tree using records Figure 10 Drawing of binary search tree dot User s Manual November 20 1996 13 Drawing graphs with dot 14 digraph structs node shape record structi shape record label lt f0 gt left lt f1 gt middle lt f2 gt right struct2 shape record label lt f0 gt one lt f1 gt two struct3 shape record label hello nworld b cl lt here gt dle f g h structi f1 gt struct2 f0 structi f2 gt2. APP SHIP DataShare ryacc Mosaic ae rank same 1988 CIA SBCS ksh 88 PEGASUS PML PAX rank same 1990 libft CoShell DIA IFS i kyacc sfio ML X DOT rank same future Adv Software Technology yeast PEGASUS PML gt ML X SCCS gt nmake SCCS gt 3D File System sccs gt RCS A make gt nmake make gt build Bourne sh gt Cshell Bourne sh gt ksh Reiser cpp gt ncpp Cshell gt ksh Figure 7 Graph with constrained ranks dot User s Manual November 20 1996 11 Drawing graphs with dot past 1980 1982 1983 1985 1987 1988 1989 1990 f future SCCS make Bourne sh yace Reiser cpp Cshell build vi emacs RCS lt curses gt SYNED IMX Y ksh IFS TTU act nmake Peggy Y ce nepp lt curses i gt ksh i PG2 t DAG CSAS 3D File System Ansi cpp fdelta nmake 2 0 y y CIA PEGASUS PML backtalk APP CIA ryace DataShare ul DOT DIA libft CoShell kyace Software IS Figure 8 Drawing with constrained ranks Adv Software Technology
3. struct3 here ONDoOFWNeH Figure 11 Records with nested fields left middle right Figure 12 Drawing of records 3 2 Concentrators Setting concentrate true on the top level graph enables an edge merging technique to reduce clutter in dense layouts Edges are merged when they run parallel and have a common endpoint A beneficial side effect in fixed sized layouts is that removal of these edges often permits larger more readable labels While dots concentrators look somewhat like Newbery s New89 they are found by searching the edges in the layout not by detecting complete bipartite graphs in the underlying graph Thus the dot approach runs much faster but doesn t collapse as many edges as Newbery s algorithm 4 Command Line Options By default dot operates in filter mode writing graphs in the input format with layout attributes appended Tps sets PostScript output Tpcl emits HPGL 2 with PCL 5 wrappers for HP Laserwriters Thpgl emits pure HPGL for wide bed pen plotters Tmif emits FrameMaker MIF files In this mode graph layouts can be loaded into FrameMaker and edited manually FrameMaker is limited to 8 basic colors Gname value sets a graph attribute default value Often it is convenient to set size pagination and related values on the command line rather than in the graph file Note that file contents override command line arguments N or E instead of G set default node or edge attributes 1 loads
4. 4 blueviolet cadetblue 1 4 cornflowerblue darkslateblue deepskyblue 1 4 dodgerblue 1 4 indigo lightblue 1 4 lightskyblue 1 4 lightslateblue 1 4 mediumblue mediumslateblue midnightblue navy navyblue powderblue royalblue 1 4 skyblue 1 4 slateblue 1 4 steelblue 1 4 Magentas blueviolet darkorchid 1 4 darkviolet magenta 1 4 mediumorchid 1 4 mediumpurple 1 4 mediumvioletred orchid 1 4 palevioletred 1 4 plum 1 4 purple 1 4 violet violetred 1 4
5. a sequence of overlapping layers Typically the layers are overhead transparencies To activate this feature one must set the graph s global layerseq to a list of identifiers A node and edge can be assigned to a a layer or range of layers all is a reserved name for all layers and can be used at either end of a range e g design al1 or all code For example layerseq spec design code debug ship node90 layer code node91 layer design debug node90 gt node91 layer all node92 layer all code In a layered graph if a node or edge has no layer assignment but incident edges or nodes do then its layer specification is inferred from these To change the default so that nodes and edges with no layer appear on all layers insert near the beginning of the graph file node layer all1 edge layer al1 There is presently no way to specify a set of layers that are not a continuous range When PostScript output is selected the color sequence for layers is set in the array layercolorseq This array is indexed starting from 1 and every element must be a 3 array to be interepreted as a color coordinate The adventurous may learn further from reading dots PostScript output dot User s Manual November 20 1996 Drawing graphs with dot E Color Names Whites antiquewhite 1 4 azure 1 4 bisque 1 4 blanchedalmond cornsilk 1 4 floralwhite gainsboro ghostwhite honeydew 1 4 ivory 1 4
6. graphics library files o sets the output file dot User s Manual November 20 1996 Drawing graphs with dot 15 1 digraph G 2 nodesep 05 3 rankdir LR 4 node shape record width 1 height 1 5 6 node0 label lt f0 gt lt f1 gt lt f2 gt lt f3 gt lt f4 gt lt f5 gt lt f6 gt height 2 5 7 node width 1 5 8 node1 label lt n gt n14 719 lt p gt 9 node2 label lt n gt al 805 lt p gt 10 node3 label lt n gt i9 718 lt p gt 11 node4 label lt n gt e5 989 lt p gt 12 node5 label lt n gt t20 959 lt p gt 13 node6 label lt n gt 015 794 lt p gt 14 node7 label lt n gt s19 659 lt p gt 15 16 nodeQ f0 gt nodei n 17 node0 f1 gt node2 n 18 node0 f2 gt node3 n 19 node0 f5 gt node4 n 20 node0 f6 gt node5 n 21 node2 p gt node6 n 22 node4 p gt node7 n 23 Figure 13 Hash table graph file pare 719 _ Pal 805 _ ec Pols 794 ce ee P20 959 Figure 14 Drawing of hash table dot User s Manual November 20 1996 Drawing graphs with dot digraph G subgraph clusterO node style filled color white style filled color lightgrey a0 gt al gt a2 gt a3 label process 1 subgraph cluster1 node style filled bO gt bi gt b2 gt b3 label process 2 color b
7. lavender lavenderblush 1 4 lemonchiffon 1 4 linen mintcream mistyrose 1 4 moccasin navajowhite 1 4 oldlace papayawhip peachpuff 1 4 seashell 1 4 snow 1 4 thistle 1 4 wheat 1 4 white whitesmoke Greys darkslategray 1 4 dimgray gray gray 0 100 lightgray lightslategray slategray 1 4 Blacks black Reds coral 1 4 crimson darksalmon deeppink 1 4 firebrick 1 4 hotpink 1 4 indianred 1 4 lightpink 1 4 lightsalmon 1 4 maroon 1 4 mediumvioletred orangered 1 4 palevioletred 1 4 pink 1 4 red 1 4 salmon 1 4 tomato 1 4 violetred 1 4 Browns beige brown 1 4 burlywood 1 4 chocolate 1 4 darkkhaki khaki 1 4 peru rosybrown 1 4 saddlebrown sandybrown sienna 1 4 tan 1 4 Oranges darkorange 1 4 orange 1 4 orangered 1 4 Yellows darkgoldenrod 1 4 gold 1 4 goldenrod 1 4 greenyellow light goldenrod 1 4 light goldenrodyellow lightyellow 1 4 palegoldenrod yellow 1 4 yellowgreen Greens chartreuse 1 4 darkgreen darkolivegreen 1 4 darkseagreen 1 4 forestgreen green 1 4 greenyellow lawngreen lightseagreen limegreen mediumseagreen mediumspringgreen mintcream olivedrab 1 4 palegreen 1 4 seagreen 1 4 springgreen 1 4 yellowgreen Cyans aquamarine 1 4 cyan 1 4 darkturquoise lightcyan 1 4 mediumaquamarine mediumturquoise paleturquoise 1 4 dot User s Manual November 20 1996 23 turquoise 1 4 Blues aliceblue blue 1
8. shape and spent considerable effort to make it robust and efficient He also wrote the GIF and ISMAP generators References Car80 M Carpano Automatic display of hierarchized graphs for computer aided decision analysis IEEE Transactions on Software Engineering SE 12 4 538 546 April 1980 GKNV93 Emden R Gansner Eleftherios Koutsofios Stephen C North and Kiem Phong Vo A Technique for Drawing Directed Graphs IEEE Trans Sofware Eng 19 3 214 230 May 1993 dot User s Manual November 20 1996 Drawing graphs with dot 20 New89 Nor92 STT81 War77 Frances J Newbery Edge Concentration A Method for Clustering Directed Graphs In 2nd International Workshop on Software Configuration Management pages 76 85 October 1989 Published as ACM SIGSOFT Software Engineering Notes vol 17 no 7 November 1989 Stephen C North Neato User s Guide Technical Report 59113 921014 14TM AT amp T Bell Laboratories Murray Hill NJ 1992 K Sugiyama S Tagawa and M Toda Methods for Visual Understanding of Hier archical System Structures IEEE Transactions on Systems Man and Cybernetics SMC 11 2 109 125 February 1981 John Warfield Crossing Theory and Hierarchy Mapping IEEE Transactions on Systems Man and Cybernetics SMC 7 7 505 523 July 1977 dot User s Manual November 20 1996 Drawing graphs with dot 21 A Graph File Grammar The following is an abstract grammar of graph files Termin
9. units 1 72 of an inch unscaled The next group of lines list the nodes in the format node name x y size ysize label_tert The name is a unique identifier If it contains whitespace or punctuation it is quoted The next group of lines list edges edge tailname headname n x1 y 2 Y2 Ln Yn Opt_text opt x opt_y n is the number of coordinate pairs that follow as Bezier spline control points If the edge is labeled then the label text and coordinates are listed as the rightmost three items on the line The last line is always stop dot User s Manual November 20 1996 Drawing graphs with dot 22 C Layout Attributes Layout coordinates are in the default PostScript coordinate system Node coordinates refer to their center points The edge spline is a list of 3n 1 points plus optional ps and optional pe points The 3n 1 points are the Bezier control points Points po p1 p2 p33 are the first bezier spline P3 P4 P5 pe are the second etc The p point is present if there s an arrow at po In this case the arrow is from po to point ps where p is actually on the node s boundary and po is further away If there is no arrow po is on the node s boundary Similarly pe is for an arrow on the other endpoint of the edge Currently edge points are listed top to bottom or left to right regardless of the orientation of the edge This may change D Layers dot has a feature for drawing a parts of a single diagram on
10. Drawing graphs with dot Eleftherios Koutsofios Stephen C North AT amp T Bell Laboratories Murray Hill NJ dot draws directed graphs as hierarchies Like its predecessor dag it is a Unix filter makes good drawings and runs quickly Its important new features are node ports for drawing data structures with pointers improved placement of nodes edge splines and labels cluster layouts and an underlying file language for graph tools Here is a reduced module dependency graph of the SML NJ compiler The layout took 3 5 seconds of user time on an HP 9000 730 computer dot User s Manual November 20 1996 Drawing graphs with dot 2 1 Basic Graph Drawing dot draws directed graphs It reads attributed graph text files and writes drawings either as graph files or in a graphics language such as PostScript dot takes four main steps in drawing a graph Knowing about these helps you to understand what kind of layouts dot makes and how you can modify its layouts The first step assigns discrete ranks to nodes In a top to bottom drawing ranks determine Y coordinates Edges that span more than one rank are broken into chains of virtual nodes and unit length edges The second step orders nodes within ranks to avoid crossings The third step sets X coordinates of nodes to keep edges short The last step routes edge splines This is the same general approach as dag which in turn builds on
11. als are shown in typewriter font and nonterminals in italics Angle brackets and indicate grouping when needed Double line brackets and enclose optional items Vertical bars separate alternatives graph strict digraph graph id stmt list stmt list stmt stmt list stmt attr stmt node stmt edge stmt subgraph id id attr stmt graph node edge attr list attr list idid attr list node stmt node id opt attrs node id gt id id opt attrs attr list edge stmt node id subgraph edgeRHS opt attrs edgeRHS edgeop node id subgraph edgeRHS subgraph subgraph id stmt list subgraph id An id is any alphanumeric string not beginning with a digit but possibly including underscores or a number or any quoted string possibly containing escaped quotes An edgeop is gt in directed graphs and in undirected graphs Semicolons aid readability but are not required except in the rare case that a named subgraph with no body immediate preceeds an anonymous subgraph because under precedence rules this sequence is parsed as a subgraph with a heading and a body B Plain Output File Format Tplain The plain output format of dot lists node and edge coordinates that are usually needed by front end programs in a line oriented style The first line is graph scalefactor bounding_boz_x bounding_boz_y All coordinates are in default
12. e than once in a graph file its contents are the union of all the nodes and edges An edge id is an optional string for referencing an edge that was previously created When set the triple tail node head node key form a unique edge key Otherwise a new internal id is generated for each distinct edge between the same pair of nodes An id may be any string 6 Conclusions dot produces nicer drawings than dag and has some features to help make more readable drawings It is not as fast as dag Since it still takes only a second or two on reasonable inputs the new features more than compensate In writing graph drawing programs we have found that it does not take long to get the first drawings but it takes a great deal of work to get truly good drawings While there is still plenty of room for improvement in dot we have accomplished our principal goals concerning aesthetics performance and new features Since the basic algorithms of dot work well we have a good basis for further research into problems such as methods for drawing large graphs and on line animated graph drawing 7 Acknowledgements We thank Emden Gansner and Phong Vo for their advice about graph drawing algorithms and programming The graph library uses Phong s splay tree dictionary library Also the users of dag gave us many good suggestions Emden Gansner Guy Jacobson and Randy Hackbarth reviewed earlier drafts of this manual John Ellson wrote the generalized polygon
13. grey is used as the default User defined style primitives can be implemented as custom PostScript procedures Such prim itives are executed inside the gsave context of a graph node or edge before any of its marks are drawn The arg lists are translated to PostScript notation For example a node with style setlinewidth 8 is drawn with a thick outline Here setlinewidth is a PostScript built in but user defined PostScript procedures are called the same way The definition of these procedures can be given in a library file loaded using 1 as shown above Edges have a dir attribute to set arrowheads dir may be forward the default back both or none This refers only to where arrowheads are drawn and does not change the underlying graph For example setting dir back does not exchange the endpoints of a directed edge unlike the dagprogram 2 3 Drawing Size and Spacing Often a drawing made with the default node sizes and separations is too big for the target printer or for the space allowed for a figure in a document There are several ways to try to deal with this problem First we will review how dot computes the final layout size A layout is initially made internally at its natural size using default settings unless ratio compress was set as described below By default nodes are at least 75 inches wide by 5 tall fonts are 14 points high nodes are separated by at least 25 and ranks by 5 There is no bound on the s
14. gt strcat 11 stringdup gt malloc fatal gt sfprintf stringdup gt strcpy stringdup gt strlen 12 fatal gt exit 13 14 subgraph cluster_error h label error h interp_err 15 16 subgraph cluster_sfio h label sfio h sfprintf 17 18 subgraph cluster_ciafan c label ciafan c ciafan computefan 19 increment 20 21 subgraph cluster_util c label util c stringdup fatal debug 22 23 subgraph cluster_query h label query h ref def 24 25 subgraph cluster_field h get_sym_fields 26 27 subgraph cluster_stdio h label stdio h stdprintf stdsprintf 28 29 subgraph cluster_ lt libc a gt getopt 30 31 subgraph cluster_stdlib h label stdlib h exit malloc free realloc 32 33 subgraph cluster_main c main 34 35 subgraph cluster_index h init_index 36 37 subgraph cluster_string h label string h strcpy strlen strcmp strcat 38 Figure 17 Call graph file dot User s Manual November 20 1996 Drawing graphs with dot 19 v requests verbose output In processing large layouts the verbose messages may give some estimate of dot s progress V prints the version number 5 Miscellaneous In the top level graph heading a graph may be declared a strict digraph This forbids the creation of self arcs and multi edges they are ignored in the input file If a subgraph appears with a body mor
15. initial layout is compressed to attempt to fit it fit it the given bounding box This trades off layout quality balance and symmetry to pack the layout more tightly Then scaling is performed as in Case 1 Case 2d If ratio auto then size is ignored and dot computes an ideal size using the following heuristic it first attempts to fit the drawing on one page by reducing to not less than 50 of its original size Otherwise the drawing is printed on multiple pages using the full area of each page and not reducing under 50 At this point if page is not set then the final layout is printed as one page If page a y is set then the layout is printed as a sequence of pages that can tiled or assembled into a mosaic Common settings are page 8 5 11 or page 11 17 These values refers to the size of the physical device and are independent of landscape mode For tiled layouts you may find it helpful to set smaller margins the default is margin 5 Although you can set margin 0 unfortunately many bitmap printers have an Internal hardware margin that cannot be overridden If rotate 90 is set then the layout is printed in landscape mode The X axis of the layout would be along the Y axis of each page This does not affect the dots interpretation of size ratio or page A common problem is that a large graph drawn at a small size yields unreadable node labels To make larger labels something has to give There is a limit to the amoun
16. into a trapezoid Though there is a way to implement custom node shapes the details are beyond the scope of this user s guide Please contact the authors for further information 2 2 Graphics Styles Nodes and edges have color and style attributes A color value can be a hue saturation brightness triple three floating point numbers between 0 and 1 or one of the colors names listed in Appendix B borrowed from some version of the X window system The numerical form is convenient for scripts or tools that automatically generate colors Color name lookup case and puncutation and insensitive so warmgrey and Warm_Grey are equivalent We can offer a few hints regarding use of color in graph drawings First avoid using too many bright colors A rainbow effect is confusing It s better to choose a narrower range of colors or to vary saturation along with hue Second when nodes are filled with dark or very saturated colors labels seem to be more readable with fontcolor white and fontname Helvetica We also have PostScript functions for dot that create outline fonts from plain fonts Third you can define your The escape N is an internal symbol for node names dot User s Manual November 20 1996 Drawing graphs with dot Node Attributes color fontcolor fontname fontsize height width label layer shape shapefile style black black Times Roman 14 5 75 node name overlay range ellipse node shape co
17. ize or aspect ratio of the drawing so if the graph is large the layout is also large If you don t specify size or ratio then the natural size layout is printed The easiest way to control the output size of the drawing is to set size y in the graph file or on the command line using G This determines the bounding box of the final layout For example size 7 5 10 fits on an 8 5x11 page assuming the default page orientation no matter how big the initial layout ratio also affects layout size There are a number of cases depending on the settings of size and ratio Case 1 ratio was not set If the drawing already fits within the given size then nothing happens Otherwise the drawing is reduced uniformly enough to make the critical dimension fit If ratio was set there are four subcases Case 2a If ratio x where x is a floating point number then the drawing is stretched adding whitespace to achieve the requested ratio expressed as drawing width height For ex ample ratio 2 0 makes the drawing twice as wide as it is high Then the layout is scaled using size as in Case l dot User s Manual November 20 1996 Drawing graphs with dot 9 Case 2b If ratio fill and size z y was set then the drawing is stretched adding whites pace to achieve the ratio x y The effect is that all of the bounding box given by size is filled Then scaling is performed as in Case 1 Case 2c If ratio compress and size x y was set then the
18. lor type face color PostScript font family point size of label height and width in inches any string all id or id id ellipse doublecircle plaintext record polygon epsf external EPSF file if epsf shape graphics options e g bold dotted filled box circle diamond Edge Attributes color decorate dir fontcolor fontname fontsize id label layer minlen style weight black forward black Times Roman 14 overlay range 1 edge stroke color if set draws a line connecting labels with their edges forward back both or none type face color PostScript font family point size of label optional value to distinguish multiple edges label if not empty all id or id id minimum rank distance between head and tail graphics options e g bold dotted filled integer reflecting importance of edge Graph Attributes center clusterrank color concentrate fontcolor fontname fontsize label layerseq margin mclimit nodesep nslimit ordering orientation page rank rankdir ranksep ratio size local black black Times Roman portrait when true centers drawing on page may be global or none background or cluster outline color enables edge concentrators when TRUE type face color PostScript font family point size of label any string idzidzid margin included in page if set to f adjusts mincross iterations by f separation between nodes in inches if set to f bounds net
19. lue start gt a0 start gt b0 al gt b3 b2 gt a3 a3 gt a0 a3 gt end b3 gt end start shape Mdiamond end shape Msquare process 2 brocess 1 Figure 15 Process diagram with clusters dot User s Manual November 20 1996 16 Drawing graphs with dot utile main Gror Cebu g sfio h sfprintf stringdup stdlib h fan error h ciafan c interp_err ref def computefan rs Stdio h ingh 17 exit malloc stdsprintf stremp k get_sym_fields Figure 16 Call graph with labeled clusters dot User s Manual November 20 1996 Drawing graphs with dot digraph G size 8 6 ratio fill node fontsize 24 1 2 3 4 ciafan gt computefan fan gt increment computefan gt fan stringdup gt fatal 5 main gt exit main gt interp_err main gt ciafan main gt fatal main gt malloc 6 main gt strcpy main gt getopt main gt init_index main gt strlen fan gt fatal T fan gt ref fan gt interp_err ciafan gt def fan gt free computefan gt stdprintf 8 computefan gt get_sym_fields fan gt exit fan gt malloc increment gt strcmp 9 computefan gt malloc fan gt stdsprintf fan gt strlen computefan gt strcmp 10 computefan gt realloc computefan gt strlen debug gt sfprintf debug
20. med src but each one must have a unique node identifier The inode number or full path name are suitable unique identifiers Then the label of each node can be set to the file name within its directory In multi line labels n 1 r terminate lines that are centered or left or right justified Graphs and cluster subgraphs may also have labels The default font is 14 point Times Roman in black Other font families sizes and colors may be selected Font names should be compatible with the target interpreter usually PostScript It is best to use only the standard font families Times Helvetica Courier or Symbol as these are guaranteed to work with any target graphics language For example Times Italic Times Bold or Courier are portable but AvanteGarde Demi0blique is not Nodes with shape record or polygon have special properties Section 3 reviews some details of using records Polygons are useful for many shapes that are not predefined They are parameterized by number of sides peripheries orientation skew and distortion as illustrated in figures 5 and 6 peripheries is the number of borders For example a doublecircle has 2 peripheries orientation is clockwise rotation from the X axis in degrees skew is a floating point number usually between 1 0 and 1 0 that distorts the shape by slanting it from top to bottom for example turning a box into a parallelogram distortion shrinks from top to bottom for example turning a box
21. node port is a point where edges may attach to a node When an edge is not attached to a port it is aimed at the node s center A node with a port specifier has the syntax name port The names and bindings of ports can differ from one node to another depending on shapes and other attributes Presently only the record shape has ports This shape represents a record as recursive lists of labeled boxes A port refers to the center of one of the boxes Ports are created by inserting the construct lt portid gt in a box label as shown in figures 9 and 10 Figures 11 and 12 shows how recursive records are drawn Vertical bars separate fields at the same level while curly braces enclose subfield lists Port identifiers are enclosed in angle brackets Literal braces vertical bars and angle brackets must be escaped Spaces are interpreted as separators between tokens similar to the way most typesetting programs work so they must be escaped if you want fixed or hard spaces Also note that records sometimes look better if their input height is set to a small value so the text labels dominate the actual size as illustrated in figure 9 Otherwise the default node size 75 by 5 is assumed as in figure 11 The example of figures 13 and 14 uses left to right drawing in a layout of a hash table 3 1 Clusters A cluster is a subgraph placed in its own distinct rectangle of the layout A subgraph is recognized as a cluster when its name has the
22. prefix cluster unless the graph s clusterrank none Cluster labels fonts colors and styles can be set in the usual way Clusters are drawn by a recursive technique that computes a rank assignment and internal ordering of nodes within clusters Figure 15 through 17 are cluster layouts and the corresponding graph files dot User s Manual November 20 1996 Drawing graphs with dot digraph asde91 ranksep 75 size 7 5 7 5 node shape plaintext fontsize 16 the time line graph past gt 1978 gt 1980 1987 gt 1988 ancestor programs gt 1982 gt 1983 gt 1985 gt 1986 gt gt 1989 gt 1990 gt future Bourne sh make SCCS yacc cron Reiser cpp Cshell emacs build vi lt curses gt RCS C rank same Software IS Configuration Mgt Architecture amp Libraries Process 3 node shape box rank same past SCCS make Bourne sh yacc cron rank same 1978 Reiser cpp Cshell rank same 1980 build emacs vi rank same 1982 RCS lt curses gt IMX SYNED rank same 1983 ksh IFS TTU rank same 1985 nmake Peggy rank same 1986 C ncpp ksh i lt curses i gt PG2 rank same 1987 Ansi cpp nmake 2 0 3D File System fdelta DAG CSAS A backtalk rank same 1989 CIA
23. raph may be set to minrank maxrank or samerank This constrains the nodes in the subgraph Figures 7 and 8 illustrate using subgraphs for controlling rank assignment In some graphs the left to right ordering of nodes is important If a subgraph has ordering out then out edges within the subgraph having the same tail node fan out from left to right in their order of creation Also when nodes are constrained to the same rank edges with non zero weight between them are aimed across the rank in the same direction left to right or top to bottom in a rotated drawing as far as possible This fact may be exploited to adjust node ordering by placing invisible edges style invis where needed Fine tuning should be approached cautiously dot works best when it can makes a layout without much help or interference in its placement of individual nodes and edges Layouts can be adjusted somewhat by increasing the weight of certain edges or by creating invisible edges or nodes using style invis and sometimes even by rearranging the order of nodes and edges in the file But this can backfire because the layouts are not necessarily stable with respect to changes in the input graph One last adjustment can invalidate all previous changes and make a very bad drawing A future project we have in mind is to combine the mathematical layout techniques of dot with an interactive front end that allows user defined hints and constraints 3 Node Ports A
24. ributes are name value pairs of character strings Figures 3 and 4 illustrate some layout attributes In the listing of figure 3 line 2 sets the graph s size to 4 4 all dimensions are in inches This attribute controls the bounding box the drawing is scaled as necessary to fit Node or edge attributes are set off in square brackets In line 3 the node main is assigned shape box The edge in line 4 is straightened by increasing its weight the default is 1 The edge in line 6 is drawn as a dotted line Line 8 makes edges from execute to make_string and printf In line 10 the default edge color is set to red This affects any edges created after this point in the file Line 11 makes a bold edge labeled 100 times In line 12 node make_string is given a multi line label Line 13 changes the default node to be a box filled with a shade of blue The node compare inherits these values lUnlike dag the GS command is not needed dot User s Manual November 20 1996 Drawing graphs with dot 1 digraph G 24 main gt parse gt execute 34 main gt init 4 main gt cleanup 5 execute gt make_string 6 execute gt printf T init gt make_string 8 main gt printf 9 execute gt compare 10 Figure 1 Small graph make_string compare Figure 2 Drawing of small graph dot User s Manual November 20 1996 Drawing graphs with dot 1 digraph G 2 size 4 4 3 main shape box this i
25. s a comment 4 main gt parse weight 8 5 parse gt execute 6 main gt init style dotted T main gt cleanup 8 execute gt make_string printf 9 init gt make_string 10 edge color red 11 main gt printf style bold label 100 times 12 make_string label make a nstring 13 node shape box style filled color 7 3 1 0 14 execute gt compare 15 Figure 3 Fancy graph 100 times make a compare string P Figure 4 Drawing of fancy graph dot User s Manual November 20 1996 Drawing graphs with dot 5 2 Drawing Attributes The complete list of attributes that affect graph drawing is summarized in table 1 2 1 Shapes and Labels By default nodes are drawn with shape ellipse width 75 height 5 and labeled by the node name Other common shapes box circle etc are listed in table 1 The node shape plaintext is of particularly interest in that it draws a node without any outline an important convention in some kinds of diagrams When drawn a node s actual size is the greater of the requested size and the area needed for its text label By default edges are unlabeled Node and edge labels can be set explicitly as shown n figure 4 Though it is convenient that nodes are labeled with their names by default sometimes it is essential to set labels explicitly For example in drawing a file directory tree one might have several directories na
26. t of readable text that can fit on one page Often you can draw a smaller graph by extracting an interesting piece of the original graph before running dot We have some tools that help with this e sccmap decompose into strongly connected components e tred compute transitive reduction remove edges implied by transitivity e gpr raph processor to select nodes or edges and contract or remove the rest of the graph e unflatten improve aspect ratio of trees by staggering the lengths of leaf edges With this in mind here are some thing to try on a given graph Increase the node fontsize Use smaller ranksep and nodesep 1 2 3 Use ratio auto 4 Use ratio compress and give a reasonable size 5 A sans serif font such as Helvetica may be more readable than Times when reduced 2 4 Node and Edge Placement Sometimes it is natural to make edges point from left to right instead of from top to bottom If rankdir LR in the top level graph the drawing is rotated in this way TB top to bottom is the default BT seems potentially useful for drawing upward directed graphs but hasn t been impelemented In some graphs you could achieve the same effect by reversing the endpoints of edges and setting their dir back dot User s Manual November 20 1996 Drawing graphs with dot 10 In graphs with time lines or in drawings that emphasize source and sink nodes you may need to constrain rank assignments The set of a subg
27. the work of Warfield War77 Carpano Car80 and Sugiyama STT81 We refer the reader to GKNV93 for explanation of dot s algorithms dot s graph language has three kinds of items graphs nodes and edges The main outermost graph can be graph undirected or a digraph directed Because dot makes layouts of directed graphs all the examples in this user s guide use digraph We have written a separate layout utility rieato to draw undirected graphs Nor92 Within a main graph a subgraph defines a subset of nodes and edges Figure 1 is an example graph in dot s language Line 1 gives the graph name and type The following lines create nodes edges or subgraphs and set attributes Names may be C identifiers numbers or quoted C strings Quotes protect punctuation or white space A node is created the first time its name appears in the file An edge is created when nodes are joined by the edge operator gt In the example line 2 makes edges from main to parse and from parse to execute Running dot on this file say graph1 dot yields the drawing of figure 2 dot Tps graphi dot o graphi ps The command line option Tps selects PostScript EPSF output graph1 ps may be printed displayed by a PostScript viewer or embedded in another document It is often useful to adjust the representation or placement of nodes and edges in the layout This is done by setting attributes of nodes edges or subgraphs in the input file Att
28. work simplex iterations by f number of nodes out for ordered edges may be set to landscape unit of pagination e g 8 5 11 same min or max LR left to right or TB top to bottom separation between ranks in inches approximate aspect ratio desired or fill drawing bounding box in inches Table 1 Drawing attributes dot User s Manual November 20 1996 Drawing graphs with dot OAONooFhWNeE Figure 5 Example of polygonal shapes for nodes digraph G a gt b gt C b gt d a shape polygon sides 5 peripheries 3 color blue_light style filled c shape polygon sides 4 skew 4 label hello world d shape invtriangle e shape polygon sides 4 distortion 7 Figure 6 Listing of graph with polygonal shapes dot User s Manual November 20 1996 Drawing graphs with dot 8 own color space by redefining nodecolor edgecolor or graphcolor in a library file For example to use RGB colors place the following line in a file lib ps nodecolor setrgbcolor bind def Use the 1 command line option to load this file dot Tps 1 lib ps file dot o file ps style controls miscellaneous graphics features of nodes edges graphs or subgraphs The style is a list of primitives with optional argument lists The predefined primitives are filled solid dashed dotted bold and invis filled when applied to nodes or clusters shades inside the boundary of the object using its color If the color is not set light
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