绘图工具graphviz学习使用

画图工具:

http://www.tuicool.com/articles/r2iAfa

http://www.tuicool.com/articles/RjQfey

绘图工具graphviz学习使用

起因

最近完成了研究生毕业设计，在写毕业论文时，老师曾经推荐使用代码来画相关的图，当时时间有些紧，所以没有这样做。最近在看rapidjson的文档，看到miloyip 文档中的图都是用dot文件的源代码编译出来的，一查，原来是graphviz的源代码。遂用了半天简单学习了下graphviz的语法和使用，感觉很不错，以后画图有了一个不错的工具。

graphviz 是一个运用广泛的命令行绘图软体，不过说是绘图软体，它能绘的图并不是一般人想像中的漫画或logo，而是数学意义上的graph，比较通俗的说法就是「关系图」。

安装

graphviz 支持 Windows、Mac OS X、FreeBSD、Solaris、Linux 等多种系统

Ubuntu或Debian下安装很简单：
```
  sudo apt-get install graphviz
```
Mac下使用brew
```
  brew install graphviz
```
Windows 下参考 http://www.graphviz.org/Download_windows.php

入门使用

1. 编写以`dot`为后缀的源代码文件，如：

// hello.dot digraph {

    	hello -> world;
	}

2. 使用`dot`命令编译，如

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

完整的命令为:

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

其中graphviz 的＜cmd＞ 有好几种，每种使用方法都完全相同，差别只在于渲染出来的图片效果不一样。man中的简介是这样的：

<cmd>	介绍
dot	渲染的图具有明确方向性。
neato	渲染的图缺乏方向性。
twopi	渲染的图采用放射性布局。
circo	渲染的图采用环型布局。
fdp	渲染的图缺乏方向性。
sfdp	渲染大型的图，图片缺乏方向性。

可以透过man ＜cmd＞ 取得进一步说明。但还是亲自用用比较容易理解。在本文中，凡没有说明的图，预设都是以dot渲染出来的。

3. 查看效果

效果如下：

语法介绍

graphviz使用dot语法来说明，其它语法可以用形式化的描述如下：

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     = ’[’ [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    = ’@’ id
edge-stmt     = (node-id | subgraph) edgeRHS [attr-list]
edgeRHS       = edgeop (node-id | subgraph) [edgeRHS]
subgraph      = [subgraph id] ’{’ stmt-list ’}’ | subgraph id

graphviz 有两种图，一种是无向图graph，边用--连接，一种是有向图digraph，边用->连接，这个可以很简单的实践。

具体的图说明内容包含属性(attr)、节点(node)、边(edge)和子图(subgraph)说明。

节点属性如下：

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 VRML output

边属性如下：

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

图属性如下：

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: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 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 ¿ 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)

实例

介绍了上面的语法，实际使用的时候就是学习几个详细的例子，下面是一个二叉树代码：

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;
}

效果如下：

python调用

除了可以使用dot文件编写图形外，也可以使用python编写相关的代码，生成图形文件，

安装方法：

pip install pygraphviz

引用 PyGraphviz：

import pygraphviz as pgv

初始化图类：

G=pgv.AGraph()

增加结点和边：

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

设置属性：

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

设置输出的格式：

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

输出到文件：

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

效果：

参考