Drawing tool Graphviz learning and use

Drawing tool Graphviz learning and use
Cause

I recently completed my graduation project. When I was writing my graduation thesis, the teacher recommended the use of code to draw related figures. At that time, the time was a little tight, so I didn't do this. I recently read the rapidjson document and see that all the images in the miloyip document usedotThe source code of the file is compiled. Check the source code of graphviz. It took me a long time to learn about it.graphvizSyntax and use, I feel very good, there will be a good tool for drawing later.

graphvizIt is a widely used command line drawing software, but it is a drawing software. It can draw a picture that is not a cartoon or logo that most people think, but a mathematicalgraphThe common saying is "Relationship Diagram 」.

Install

Graphviz supports Windows, Mac OS X, FreeBSD, Solaris, Linux, and other systems.

• Ubuntu or Debian is easy to install:

    sudo apt-get install graphviz

• Use brew in Mac

    brew install graphviz

• Windows reference http://www.graphviz.org/Download_windows.php

Getting started

1. WritedotSource code file with a suffix, such:

// Hello. dot digraph {

    hello -> world;}

2. UsedotCommand compilation, such

Dot hello. dot-T png-o hello.png

The complete command is:

<Cmd> <inputfile>-T <format>-o <outputfile>

The graphviz＜cmd＞There are several different types of images, each of which is used in the same way. The difference is that the rendered images have different effects.manThe introduction in is as follows:

<Cmd>	Introduction
Dot	The rendered graph has clear directionality.
Neato	The rendered graph lacks directionality.
Twopi	The rendered graph uses a radioactive layout.
Circo	The rendered graph adopts a ring layout.
Fdp	The rendered graph lacks directionality.
Sfdp	The rendering of large images lacks directionality.

You canman ＜cmd＞For further instructions. However, it is easier to use it in person. In this article, any graph that is not described isdotRendered.

3. view results

The effect is as follows:

Syntax Introduction

Graphviz uses the dot syntax. Other syntaxes can be formally described as follows:

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-listattr-list     = ’[’ [a-list ] ’]’ [attr-list] a-list        = id ’=’ id [’,’] [a-list] node-stmt     = node-id [attr-list]node-id       = id [port]port          = port-location [port-angle] | port-angle [port-location] port-location = ’:’ id|’:’ ’(’id’,’id’)’port-angle    = ’@’ idedge-stmt     = (node-id | subgraph) edgeRHS [attr-list]edgeRHS       = edgeop (node-id | subgraph) [edgeRHS]subgraph      = [subgraph id] ’{’ stmt-list ’}’ | subgraph id

Graphviz has two types of graphs. One is an undirected graph.graph, Edge use--Connection, a Directed Graphdigraph, Edge use->Connection. This can be a simple practice.

The specific graph description includes the attributes (attr), node, edge, and subgraph descriptions.

The node attributes are as follows:

Name	Default	Values
Color	Black	Node shape color
Comment		Any string (format-dependent)
Distortion	0.0	Node distortion for shape = polygon
Fillcolor	Lightgrey/black	Node fill color
Fixedsize	False	Label text has no affect on node size
Fontcolor	Black	Type face color
Fontname	Times-Roman	Font family
Fontsize	14	Point size of label
Group		Name of node's group
Height	. 5	Height in inches
Label	Node name	Any string
Layer	Overlay range	All, id or id: id
Orientation	0.0	Node rotation angle
Peripheries	Shape-dependent	Number of node boundaries
Regular	False	Force polygon to be regular
Shape	Ellipse	Node shape; see Section 2.1 and Appendix E
Shapefile		External EPSF or SVG custom shape file
Sides	4	Number of sides for shape = polygon
Skew	0.0	Skewing of node for shape = polygon
Style		Graphics options, e.g. bold, dotted, filled; cf. Section 2.3
URL		URL associated with node (format-dependent)
Width	. 75	Width in inches
Z	0.0	Z coordinate for fig output

Edge attributes are as follows:

Name	Default	Values
Arrowhead	Normal	Style of arrowhead at head end
Arrowsize	1.0	Scaling factor for arrowheads
Arrowtail	Normal	Style of arrowhead at tail end
Color	Black	Edge stroke color
Comment		Any string (format-dependent)
Constraint	True	Use edge to affect node ranking
Decorate		If set, draws a line connecting labels with their edges
Dir	Forward	Forward, back, both, or none
Fontcolor	Black	Type face color
Fontname	Times-Roman	Font family
Fontsize	14	Point size of label
Headlabel		Label placed near head of edge
Headport		N, ne, e, se, s, sw, w, nw
HeadURL		URL attached to head label if output format is ismap
Label		Edge label
Labelangle	-25.0	Angle in degrees which head or tail label is rotated off edge
Labeldistance	1.0	Scaling factor for distance of head or tail label from node
Labelfloat	False	Lessen constraints on edge label placement
Labelfontcolor	Black	Type face color for head and tail labels
Labelfontname	Times-Roman	Font family for head and tail labels
Labelfontsize	14	Point size for head and tail labels
Layer	Overlay range	All, id or id: id
Lhead		Name of cluster to use as head of edge
Ltail		Name of cluster to use as tail of edge
Minlen	1	Minimum rank distance between head and tail
Samehead		Tag for head node; edge heads with the same tag are
Sametail		Merged onto the same port
Style		Tag for tail node; edge tails with the same tag are merged onto the same port
Taillabel		Graphics options, e.g. bold, dotted, filled; cf. Section 2.3
Tailport		Label placed near tail of edge n, ne, e, se, s, sw, w, nw
TailURL		URL attached to tail label if output format is ismap
Weight	1	Integer cost of stretching an edge

The figure attributes are as follows:

Name	Default	Values
Bgcolor		Background color for drawing, plus initial fill color
Center	False	Center drawing on page
Clusterrank	Local	May be global or none
Color	Black	For clusters, outline color, and fill color if fillcolor not defined
Comment		Any string (format-dependent)
Compound	False	Allow edges between clusters
Concentrate	False	Enables edge concentrators
Fillcolor	Black	Cluster fill color
Fontcolor	Black	Type face color
Fontname	Times-Roman	Font family
Fontpath		List of directories to search for fonts
Fontsize	14	Point size of label
Label		Any string
Labeljust	Centered	"L" and "r" for left-and right-justified cluster labels, respectively
Labelloc	Top	"T" and "B" for top-and bottom-justified cluster labels, respectively
Layers		Id: id...
Margin	. 5	Margin included in page, inches
Mclimit	1.0	Scale factor for mincross iterations
Nodesep	. 25	Separation between nodes, in inches.
Nslimit		If set to f, bounds network simplex iterations by (f) (number of nodes) when setting x-coordinates
Nslimit1		If set to f, bounds network simplex iterations by (f) (number of nodes) when ranking nodes
Ordering		If out edge order is preserved
Orientation	Portrait	If rotate is not used and the value is landscape, use landscape orientation
Page		Unit of pagination, e.g. "8.5, 11"
Pagedir	BL	Traversal order of pages
Quantum		If quantum limit 0.0, node label dimensions will be rounded to integral multiples of quantum
Rank		Same, min, max, source or sink
Rankdir	TB	LR (left to right) or TB (top to bottom)
Ranksep	. 75	Separation between ranks, in inches.
Ratio		Approximate aspect ratio desired, fill or auto
Remincross		If true and there are multiple clusters, re-run crossing minimization
Rotate		If 90, set orientation to landscape
Samplepoints	8	Number of points used to represent ellipses and circles on output (cf. Appendix C
Searchsize	30	Maximum edges with negative cut values to check when looking for a minimum one during network simplex
Size		Maximum drawing size, in inches
Style		Graphics options, e.g. filled for clusters
URL		URL associated with graph (format-dependent)

Instance

The above syntax is introduced. In actual use, we will learn several detailed examples. Below is a binary tree code:

digraph g {    node [shape = record,height=.1];    node0[label = "<f0> |<f1> G|<f2> "];    node1[label = "<f0> |<f1> E|<f2> "];    node2[label = "<f0> |<f1> B|<f2> "];    node3[label = "<f0> |<f1> F|<f2> "];    node4[label = "<f0> |<f1> R|<f2> "];    node5[label = "<f0> |<f1> H|<f2> "];    node6[label = "<f0> |<f1> Y|<f2> "];    node7[label = "<f0> |<f1> A|<f2> "];    node8[label = "<f0> |<f1> C|<f2> "];    "node0":f2 -> "node4":f1;    "node0":f0 -> "node1":f1;    "node1":f0 -> "node2":f1;    "node1":f2 -> "node3":f1;    "node2":f2 -> "node8":f1;    "node2":f0 -> "node7":f1;    "node4":f2 -> "node6":f1;    "node4":f0 -> "node5":f1;}

The effect is as follows:

Python call

In additiondotIn addition to writing graphics, you can also use python to write relevant code to generate graphical files,

Installation Method:

pip install pygraphviz

ReferencePyGraphviz:

import pygraphviz as pgv

Initialize graph class:

G=pgv.AGraph()

Add nodes and edges:

G.add_node('a') # adds node 'a'G.add_edge('b','c') # adds edge 'b'-'c' (and also nodes 'b', 'c')

Set attributes:

G.graph_attr['label']='test graphf'G.node_attr['shape']='circle'G.edge_attr['color']='red'

Set the output format:

G.layout() # default to neatoG.layout(prog='dot') # use do

Output to file:

G.draw('file.png')  # write previously positioned graph to PNG fileG.draw('file.ps',prog='circo') # use circo to position, write PS file

Effect:

Reference

• Dotguide
• Solve Graphviz usage and Chinese garbled characters
• Rapidjson
• PyGraphviz tutorial

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