问题描述
我试图将包含单个有向图的GraphML文件读入Haskell中。 rel =nofollow> Data.Graph 为了使用模块。 p>
然而，我找不到任何模块允许我读取GraphML文件，产生一个 Data.Graph 。我找到的一个相关模块是。但是，这似乎是特定于 ForSyDe DSL，我目前无法想出一种方法来使用它来读取一个普通的 Data.Graph 。
你能指点我一个库让我阅读GraphML，最好是有关如何使用它的一些示例代码？
经过一周多的搜索之后，我认为目前没有GraphML解析器库存在。因此，我写了我自己的最小解析器。
假设我们有这个GraphML：
<？xml version =1.0encoding =UTF-8？>
< graphml xmlns =http://graphml.graphdrawing.org/xmlns
xmlns：xsi =http://www.w3.org/2001/XMLSchema-instance
xsi：schemaLocation =http://graphml.graphdrawing.org/xmlns
http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd\">
< graph id =Gedgedefault =undirected>
< node id =n0/>
< node id =n1/>
< node id =n2/>
< node id =n3/>
< edge id =e1source =n0target =n1/>
< edge id =e1source =n1target =n2/>
< edge id =e1source =n1target =n3/>
< edge id =e1source =n3target =n0/>
< /图表>
< / graphml>
我创建了这个基于HXT的解析器，它能够解析GraphML的最小子集（刚够创建）。以下文件的 main 函数表示如何使用它的示例：它会打印图中节点的列表（另请参阅 I'm trying to read a GraphML file containing a single directed Graph into a Haskell Data.Graph in order to run an analysis using the Math.Combinatorics.Graph module. However, I can't find any module that allows me to read a GraphML file, producing a Data.Graph. One related module I found is ForSyDe.Backend.GraphML. However, this seems to be specific to the ForSyDe DSL and I currently can't think of a way to use it to read a plain Data.Graph. Could you point me to a library allowing me to read GraphML, preferably with some example code on how to use it? After more than a week of searching, I assume there is currently no GraphML parser library in existence. Therefore I wrote my own minimal parser. Let's assume we have this GraphML: I created this HXT-based parser that's able to parse a minimal subset of GraphML (just enough to create a Data.Graph of the above GraphML). The main function of the following file represents an example of how to use it: It prints the list of nodes in the graph (also see this related question ). 这篇关于在Haskell中读取GraphML的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ { - ＃LANGUAGE箭头，NoMonomorphismRestriction＃ - }
导入Text.XML.HXT.Core
将限定的Data.Graph导入为DataGraph
data Graph = Graph
{graphId :: String，
nodes :: [String]，
edges :: [（String，String）] - （Source，target）
}
deriving（ Show，Eq）
atTag tag = deep（isElem>>> hasName标签）
parseEdges = atTagedge>>>
proc e - > do
source< - getAttrValuesource - < e
target< - getAttrValuetarget - < e
returnA - < （来源，目标）
parseNodes = atTag节点>>>
proc n - > do
nodeId< - getAttrValueid - < n
returnA - < nodeId
parseGraph = atTag图形>>>
proc g - > do
graphId< - getAttrValueid - < g
节点< - listA parseNodes - < g
edges< - listA parseEdges - < g
returnA - < Graph {graphId = graphId，nodes = nodes，edges = edges}
getEdges = atTagedge>>> getAttrValuesource
- 获取Graph中单个节点的目标
getTargets :: String - >图表 - > [String]
getTargets source graph = map snd $ filter（（== source）.fst）$ edges图形
- 将图形节点转换为Data.Graph可用的
getDataGraphNode :: Graph - >字符串 - > （String，String，[String]）
getDataGraphNode图节点=（节点，节点，getTargets节点图）
- 将Graph实例转换为Data.Graph列表（节点， nodeid，edge）元组
getDataGraphNodeList :: Graph - > [（String，String，[String]）]
getDataGraphNodeList graph = map（getDataGraphNode graph）（nodes graph）
$ b $ main :: IO（）
main = do
graph< - runX（readDocument [withValidate no]foo.graphml>>> parseGraph）
- 将Graph结构转换为Data.Graph可导入的元组列表
let graphEdges = getDataGraphNodeList $头图
- 转换为Data.Graph
let（graph，vertexMap）= DataGraph.graphFromEdges'graphEdges
- 如何处理图形：打印顶点
print $ map（（\（vid，_，_） - > vid）。vertexMap）（DataGraph.vertices graph）
<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns
http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
<graph id="G" edgedefault="undirected">
<node id="n0"/>
<node id="n1"/>
<node id="n2"/>
<node id="n3"/>
<edge id="e1" source="n0" target="n1"/>
<edge id="e1" source="n1" target="n2"/>
<edge id="e1" source="n1" target="n3"/>
<edge id="e1" source="n3" target="n0"/>
</graph>
</graphml>
{-# LANGUAGE Arrows, NoMonomorphismRestriction #-}
import Text.XML.HXT.Core
import qualified Data.Graph as DataGraph
data Graph = Graph
{ graphId :: String,
nodes :: [String],
edges :: [(String, String)] -- (Source, target)
}
deriving (Show, Eq)
atTag tag = deep (isElem >>> hasName tag)
parseEdges = atTag "edge" >>>
proc e -> do
source <- getAttrValue "source" -< e
target <- getAttrValue "target" -< e
returnA -< (source, target)
parseNodes = atTag "node" >>>
proc n -> do
nodeId <- getAttrValue "id" -< n
returnA -< nodeId
parseGraph = atTag "graph" >>>
proc g -> do
graphId <- getAttrValue "id" -< g
nodes <- listA parseNodes -< g
edges <- listA parseEdges -< g
returnA -< Graph{graphId=graphId, nodes=nodes, edges=edges}
getEdges = atTag "edge" >>> getAttrValue "source"
-- Get targets for a single node in a Graph
getTargets :: String -> Graph -> [String]
getTargets source graph = map snd $ filter ((==source).fst) $ edges graph
-- Convert a graph node into a Data.Graph-usable
getDataGraphNode :: Graph -> String -> (String, String, [String])
getDataGraphNode graph node = (node, node, getTargets node graph)
-- Convert a Graph instance into a Data.Graph list of (node, nodeid, edge) tuples
getDataGraphNodeList :: Graph -> [(String, String, [String])]
getDataGraphNodeList graph = map (getDataGraphNode graph) (nodes graph)
main :: IO()
main = do
graphs <- runX (readDocument [withValidate no] "foo.graphml" >>> parseGraph)
-- Convert Graph structure to Data.Graph-importable tuple list
let graphEdges = getDataGraphNodeList $ head graphs
-- Convert to a Data.Graph
let (graph, vertexMap) = DataGraph.graphFromEdges' graphEdges
-- Example of what to do with the Graph: Print vertices
print $ map ((\ (vid, _, _) -> vid) . vertexMap) (DataGraph.vertices graph)