用python替换xml中的树元素

Question

#!/usr/bin/env python 

import libxml2 

import os.path 

from cfs_utils import * 

solvers = ["CG","CGS","BICGSTABL"] 
precond = ["saamg","iluk","ssor"] 
for s in range(3): 
for p in range(3): 
    print "s " + str(s) 
    problem = "eval_" + str(solvers[s]) + "_" + str(precond[p]) + "_default" 

#if os.path.exists(problem + ".info.xml"): 
# continue 

print "execute " + problem + "\n" 

doc = libxml2.parseFile("simp_lis_solver_3D.xml") 
xml = doc.xpathNewContext() 
solver = xml.xpathEval('//solverList') 
xml.setContextNode(solvers) 
solver_name = xml.xpathEval(solvers[s]) 

这里我想用指定的求解器名称替换xml元素，我尝试用下面的方式在下面进行人工合成，但没有任何工作。

#[0].getContent() 
    # xml.xpathRegisterNs('cfs', 'http://www.cfs++.org') 
    #replace(xml, "//cfs:volume/@value", str(vol)) 
    # replace("pardiso", "CG", "CGS") 
for line in doc: 
    solvers[s].replace('TFQMR', 'CG') 
    doc.saveFile(problem + ".xml") 
    execute("cfs.rel -m bulk3d_10.mesh " + problem) 

下面是一个使用此XML文件，我想在我的Python代码指定的解算器，以取代求解TFGMR我的XML文件，这里的样品。

<system> 
    <solutionStrategy> 
     <standard> 
     <matrix storage="sparseNonSym"/> 
     </standard> 
    </solutionStrategy> 
    <solverList> 
     <lis id="default"> 
     <precond><saamg/> 
     </precond> 
     <solver> 
     <TFQMR></TFQMR> 
    </solver> 
     <maxIter>10000</maxIter> 
     <tolerance>1.0E-10</tolerance> 
     <logging>false</logging> 
     </lis> 
    </solverList> 
    </system> 
</linearSystems> 

Answer 1

您可以从父去除，然后更换使用xml.ElementTree：

from xml.etree import ElementTree as et 

tree = et.parse("your.xml") 
x = tree.getroot() 


for s in x.findall(".//solver"): 
    ch = s.find("./TFQMR") 
    if ch is not None: 
     s.remove(ch) 
     s.append(et.SubElement(s, "CG")) 

print(et.tostring(x)) 

使用您的片段：

In [55]: from xml.etree import ElementTree as et 

In [56]: tree = et.parse("test.xml") 

In [57]: x = tree.getroot() 

In [58]: for s in x.findall(".//solver"): 
    ....:  ch = s.find("./TFQMR") 
    ....:  if ch is not None: 
    ....:    s.remove(ch) 
    ....:    s.append(et.SubElement(s, "CG")) 
    ....:print(et.tostring(x)) 
    ....:   
<system> 
    <solutionStrategy> 
      <standard> 
       <matrix storage="sparseNonSym" /> 
      </standard> 
    </solutionStrategy> 
    <solverList> 
     <lis id="default"> 
      <precond> 
       <saamg /> 
      </precond> 
      <solver> 
       <CG /><CG /></solver> 
      <maxIter>10000</maxIter> 
      <tolerance>1.0E-10</tolerance> 
      <logging>false</logging> 
     </lis> 
    </solverList> 
</system> 

使用你的文件，你需要注册命名空间：

from xml.etree import ElementTree as et 

tree = et.parse(.xml") 
x = tree.getroot() 

namespaces = {'cfsSimulation': "http://www.cfs++.org"} 

solvers = x.findall(
"cfsSimulation:sequenceStep/cfsSimulation:linearSystems/cfsSimulation:system" 
"//cfsSimulation:solverList/cfsSimulation:lis/cfsSimulation:solver",namespaces) 
for s in solvers: 
    ch = s.find("./cfsSimulation:TFQMR", namespaces) 
    if ch is not None: 
     s.remove(ch) 
     s.append(et.SubElement(s, "CG")) 

print(et.tostring(x))