如何循環GraphML與LXML

Question

文件我有以下GraphML文件「mygraph.gml」，我想用一個簡單的python腳本解析：

這代表了一個簡單圖2個節點「NODE0」，「節點1" 並把它們

<?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"> 
    <key id="name" for="node" attr.name="name" attr.type="string"/> 
    <key id="weight" for="edge" attr.name="weight" attr.type="double"/> 
    <graph id="G" edgedefault="directed"> 
    <node id="n0"> 
     <data key="name">node1</data> 
    </node> 
    <node id="n1"> 
     <data key="name">node2</data> 
    </node> 
<edge source="n1" target="n0"> 
    <data key="weight">1</data> 
</edge> 
    </graph> 
</graphml> 

之間的邊緣這代表具有兩個節點N0和N1與權重1之間的邊緣的曲線圖。 我想用python解析這個結構。

我寫了一個腳本LXML的幫助（我需要使用它，因爲比這個簡單的例子非常非常大的數據集，超過10^5個節點，蟒蛇minidom命名太慢）

import lxml.etree as et 

tree = et.parse('mygraph.gml') 

root = tree.getroot() 

graphml = { 
"graph": "{http://graphml.graphdrawing.org/xmlns}graph", 
"node": "{http://graphml.graphdrawing.org/xmlns}node", 
"edge": "{http://graphml.graphdrawing.org/xmlns}edge", 
"data": "{http://graphml.graphdrawing.org/xmlns}data", 
"label": "{http://graphml.graphdrawing.org/xmlns}data[@key='label']", 
"x": "{http://graphml.graphdrawing.org/xmlns}data[@key='x']", 
"y": "{http://graphml.graphdrawing.org/xmlns}data[@key='y']", 
"size": "{http://graphml.graphdrawing.org/xmlns}data[@key='size']", 
"r": "{http://graphml.graphdrawing.org/xmlns}data[@key='r']", 
"g": "{http://graphml.graphdrawing.org/xmlns}data[@key='g']", 
"b": "{http://graphml.graphdrawing.org/xmlns}data[@key='b']", 
"weight": "{http://graphml.graphdrawing.org/xmlns}data[@key='weight']", 
"edgeid": "{http://graphml.graphdrawing.org/xmlns}data[@key='edgeid']" 
} 

graph = tree.find(graphml.get("graph")) 
nodes = graph.findall(graphml.get("node")) 
edges = graph.findall(graphml.get("edge")) 

這個腳本得到正確的節點和邊緣，使我可以在他們簡單地重複

for n in nodes: 
    print n.attrib 

上邊緣

或類似：

for e in edges: 
    print (e.attrib['source'], e.attrib['target']) 

但我無法真正理解如何獲得邊或節點的「數據」標籤以打印邊緣權重和節點標籤「名稱」。

這並沒有爲我工作：

weights = graph.findall(graphml.get("weight")) 

最後的名單始終是空的。爲什麼？我錯過了一些東西，但不明白是什麼。

Answer 1

你不能做一個合格，但發現每一個節點，你可以建立一個字典數據的鍵/值：

graph = tree.find(graphml.get("graph")) 
nodes = graph.findall(graphml.get("node")) 
edges = graph.findall(graphml.get("edge")) 

for node in nodes + edges: 
    attribs = {} 
    for data in node.findall(graphml.get('data')): 
     attribs[data.get('key')] = data.text 
    print 'Node', node, 'have', attribs 

它給出的結果：

Node <Element {http://graphml.graphdrawing.org/xmlns}node at 0x7ff053d3e5a0> have {'name': 'node1'} 
Node <Element {http://graphml.graphdrawing.org/xmlns}node at 0x7ff053d3e5f0> have {'name': 'node2'} 
Node <Element {http://graphml.graphdrawing.org/xmlns}edge at 0x7ff053d3e640> have {'weight': '1'}