如何在R中使用xpath來獲取多個xml屬性

我想從xml文件中讀取一些數據並將這些數據嵌入到R腳本中，以便可以生成散點圖。但是，問題是一個標籤有幾個屬性，我不知道如何處理。請你幫幫我嗎？如何在R中使用xpath來獲取多個xml屬性

例如，在下面的xml文件中，我想要讀取VertexConnectivity2的所有結果。也許我的其他問題和答案可以給你一個提示。

<?xml version="1.0" encoding="UTF-8"?> 
<MappingTest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://sourceforge.net/projects/alevin/ ./Alevin.xsd" xmlns="http://sourceforge.net/projects/alevin/" name="AdvSubgraphTestGenerator2"> 
    <TestGenerator className="tests.generatorTests.AdvSubgraphTestRunner"/> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="7.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="1612.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="1.6851389854194017"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.9861088559313271"/> 
    <ScenarioMetric name="StochasticMetric2" result="0.7559889069056674"/> 
    <ScenarioMetric name="VertexConnectivity0" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="0.6648338346749284"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="2.279045304613785"/> 
    <ScenarioMetric name="StochasticMetric0" result="0.4505067333055669"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="8.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="846.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="1.741814530894711"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="1.0019396461682453"/> 
    <ScenarioMetric name="StochasticMetric2" result="0.868390100905683"/> 
    <ScenarioMetric name="VertexConnectivity0" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="1.854673959898261"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="1.295691487310222"/> 
    <ScenarioMetric name="StochasticMetric0" result="0.6805885859898158"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="9.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="609.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.212517958069722"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.08677137867839191"/> 
    <ScenarioMetric name="StochasticMetric2" result="1.9927278019276755"/> 
    <ScenarioMetric name="VertexConnectivity0" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="1.6370875136672722"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="1.8573960873462065"/> 
    <ScenarioMetric name="StochasticMetric0" result="1.7266332660325572"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="10.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="578.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.145412191385898"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.826946783775961"/> 
    <ScenarioMetric name="StochasticMetric2" result="1.8202071941911595"/> 
    <ScenarioMetric name="VertexConnectivity0" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="1.5890364574294114"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="2.2117994159315804"/> 
    <ScenarioMetric name="StochasticMetric0" result="1.1993780131111107"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="11.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="797.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.3954850079335364"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.019578501527560466"/> 
    <ScenarioMetric name="StochasticMetric2" result="3.0860109027715414"/> 
    <ScenarioMetric name="VertexConnectivity0" result="3.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="1.854555495387745"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="3.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="3.584217996538307"/> 
    <ScenarioMetric name="StochasticMetric0" result="2.1648172533072234"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="12.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="892.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.4913004237744385"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.7696498939789347"/> 
    <ScenarioMetric name="StochasticMetric2" result="2.201723978314626"/> 
    <ScenarioMetric name="VertexConnectivity0" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="2.04191205905592"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="2.376993537716656"/> 
    <ScenarioMetric name="StochasticMetric0" result="3.034262661127799"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="13.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="872.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.047126232292386"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.9952229587725951"/> 
    <ScenarioMetric name="StochasticMetric2" result="3.3794406500249257"/> 
    <ScenarioMetric name="VertexConnectivity0" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="1.6523543005400327"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="3.048441149178422"/> 
    <ScenarioMetric name="StochasticMetric0" result="3.133358034963522"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="14.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="891.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="1.987660356945407"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.2484076205543828"/> 
    <ScenarioMetric name="StochasticMetric2" result="3.9080988222890496"/> 
    <ScenarioMetric name="VertexConnectivity0" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="2.1670218484160566"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="3.2472187629267433"/> 
    <ScenarioMetric name="StochasticMetric0" result="3.1328785000072386"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="15.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="1162.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.2234619923069414"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.45771183680269933"/> 
    <ScenarioMetric name="StochasticMetric2" result="2.9215253413041196"/> 
    <ScenarioMetric name="VertexConnectivity0" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="2.054840069986192"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="3.442550183039827"/> 
    <ScenarioMetric name="StochasticMetric0" result="3.995284651861695"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="16.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="1113.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.0926238844236447"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.7808319615152142"/> 
    <ScenarioMetric name="StochasticMetric2" result="3.0087947748201787"/> 
    <ScenarioMetric name="VertexConnectivity0" result="1.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="2.1883371528470357"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="1.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="3.710605434"/> 
    <ScenarioMetric name="StochasticMetric0" result="2.7728208750298773"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="17.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="2454.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="2.23606797749979"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.0"/> 
    <ScenarioMetric name="StochasticMetric2" result="4.143188604518091"/> 
    <ScenarioMetric name="VertexConnectivity0" result="4.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="3.2916550003635034"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="4.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="2.7605883080698828"/> 
    <ScenarioMetric name="StochasticMetric0" result="5.220399731228472"/> 
    </ScenarioResult> 
    <ScenarioResult> 
    <ScenarioParameter name="Waxman_alpha" value="0.4"/> 
    <ScenarioParameter name="Waxman_beta" value="0.5"/> 
    <ScenarioParameter name="NumVNodesPerNet" value="18.0"/> 
    <ScenarioParameter name="NumVNets" value="1.0"/> 
    <ScenarioParameter name="SNetSize" value="100.0"/> 
    <ScenarioParameter name="Min_BW_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_BW_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_BW_Res" value="30.0"/> 
    <ScenarioParameter name="Max_BW_Res" value="100.0"/> 
    <ScenarioParameter name="Min_CPU_Dem" value="10.0"/> 
    <ScenarioParameter name="Max_CPU_Dem" value="50.0"/> 
    <ScenarioParameter name="Min_CPU_Res" value="30.0"/> 
    <ScenarioParameter name="Max_CPU_Res" value="100.0"/> 
    <ScenarioParameter name="NumberOfRun" value="1.0"/> 
    <ScenarioMetric name="Runtime" result="2516.0"/> 
    <ScenarioMetric name="RejectedNetworksNumber" result="0.0"/> 
    <ScenarioMetric name="VertexConnectivity2" result="2.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity2" result="1.9840593925343335"/> 
    <ScenarioMetric name="EdgeConnectivity2" result="2.0"/> 
    <ScenarioMetric name="FabianianCoefficient2" result="1.0"/> 
    <ScenarioMetric name="SpectralGap2" result="0.3636812390986559"/> 
    <ScenarioMetric name="StochasticMetric2" result="4.238514242266579"/> 
    <ScenarioMetric name="VertexConnectivity0" result="3.0"/> 
    <ScenarioMetric name="AlgebraicConnectivity0" result="2.2503830421805113"/> 
    <ScenarioMetric name="EdgeConnectivity0" result="3.0"/> 
    <ScenarioMetric name="FabianianCoefficient0" result="1.0"/> 
    <ScenarioMetric name="SpectralGap0" result="4.0227880048448625"/> 
    <ScenarioMetric name="StochasticMetric0" result="6.649563197244915"/> 
    </ScenarioResult> 
</MappingTest>

來源

2014-11-01 Fab Ian

您可以使用xmlGetAttr與name = "result"：

library(XML) 
doc <- xmlParse(xData) 
res <- doc['//*[@name = "VertexConnectivity2"]' 
    , fun = function(x) xmlGetAttr(x, "result")] 
> as.numeric(res) 
[1] 1 1 2 1 2 2 2 2 2 1 2 2

或可供選擇的XPath內選擇result屬性：

library(XML) 
doc <- xmlParse(xData) 
> as.numeric(doc['//*[@name = "VertexConnectivity2"]/@result']) 
[1] 1 1 2 1 2 2 2 2 2 1 2 2

要「選擇NumVNodesPerNet = 「14」，這樣我只具有NumVNodesPerNet = 14的值vertexConnectivity2「，您可以逐步將其分解。

找到節點與屬性name="NumVNodesPerNet"和具有屬性value="14.0"：

//*[@name="NumVNodesPerNet" and @value="14.0"]
從這個節點回到父：

/..
從這父節點選擇h的節點作爲屬性name = "VertexConnectivity2"

/*[@name = "VertexConnectivity2"]
從我們的最終節點

/@result

選擇結果屬性把他們放在一起，我們有：

myXpath <- '//*[@name="NumVNodesPerNet" and @value="14.0"]/../*[@name = "VertexConnectivity2"]/@result' 
> as.numeric(doc[myXpath]) 
[1] 2

來源

2014-11-01 09:47:56 jdharrison

謝謝。也許你還可以告訴我如何將字符串轉換爲浮點數，以及如何選擇NumVNodesPerNet =「14」，以便我只將NumVNodesPerNet = 14的值vertexConnectivity2表示爲浮點數。 – 2014-11-02 00:26:34

您可以使用'as.numeric'將結果列表轉換爲數字。 – jdharrison 2014-11-02 00:49:11

非常感謝 – 2014-11-02 08:25:24

如何在R中使用xpath來獲取多個xml屬性

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