Need help to write data onto an XML file after reading data fromanother xml file

Discussion in 'Python' started by varun7rs, May 13, 2014.

  1. varun7rs

    varun7rs Guest

    Hello Users,

    I am in dire need of your help. I have been working on this code for quite some time and it is making me restless. All I am trying to do is,

    1. Read data from an xml file. Source:

    2. The data I'm concerned about is the node ID, co-ordinates, capacity of the links, source and destination names.

    3. I'm creating a topology with this information and the topology is same as the one given in the xml file. But, I'd like to add a few extra parameters and demands which I have mentioned in the .py file.

    4. This is where I am faltering. I am just not able to create this topology. The file has also become really messy as I tried a lot of weird stuff and commented it out as it did not work.

    5. I'll attach the relevant files and I'd like to write the output onto a new xml file.

    I'd be glad if any of you could help me out. I'm indebted to you guys. Oh I was not aware that I could attach files. Anyways, here is the link to the files I'm working on

    Thanks a lot everyone
    varun7rs, May 13, 2014
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  2. varun7rs

    Dave Angel Guest

    Try to include the relevant information in your message. Many people
    cannot, or will not, follow links. Further, those links are frequently
    transient (such as your dropbox one), which means the message thread
    becomes historically useless. So a link to point to a particular
    library is useful and practical, one to your source code is not.

    And many readers cannot see attachments or html formatted messages.
    Dave Angel, May 14, 2014
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  3. varun7rs

    varun7rs Guest

    I try to add an edge with the source id and destination id over a loop but this is the error I am getting. And the range for the for addEdge is something I have no clue about.

    python --output topology.xml --xml germany50.xml
    Traceback (most recent call last):
    File "", line 239, in <module>
    File "", line 234, in main
    network.addEdge( PHY_LINKS( j , sourcen, destnn, sid, did, cap_bdw) )
    File "/home/srva/", line 89, in addEdge
    self.nodes[ edge.SourceID ].addInEdge( edge )
    IndexError: list index out of range

    Thank You
    varun7rs, May 14, 2014
  4. varun7rs

    Dave Angel Guest

    Thanks for posting a complete stack trace, it can be a real help. You
    still have not shown us the source code. Did you write it yourself, or
    are you just trying to debug something written by someone else?

    In particular, the exception occurs in Is that your
    file, and can you edit it to ferret out the problem? Do you know what
    attributes are supposed to be of what types?

    I peaked; I actually took a look at your dropbox files. So I have some
    comments, though they may not help debug the problem. After all, there
    are hundreds of lines of code,

    First, you don't mention the Python version nor the OS you're using.
    Indirectly, I can surmise Python 2.7 and Linux, but it's much safer to
    declare such things in the problem descrition.

    Assuming 2.x, you're using old-style classes. While that might not be a
    bug, they've been obsolete for at least a decade. You need to derive
    each of your classes from object. So, you should have for example:

    class CplexSolver(object):

    next, you have way too few comments. I can't even tell why you put
    certain classes and functions in one file, versus others in another file.

    Next, you don't follow Pep8, or any other reasonable standard, for
    naming. Thus, I can't tell readily whether a particular name is a class
    name, an attribute, a method, or whatever. If the code were smaller, I
    might be willing to work it out, and make myself a crossref, but that's
    why you should simplify a problem you're asking for help with. If the
    code is 700 lines, few people are going to be willing to study it unless
    it's very well commented and easy to follow.

    You have a name PHY_NETWORK, which being all caps would indicate it's a
    const, but instead it's actually a class. It has a method addEdge(),
    which takes an argument edge. But it's not obvious to me what class
    that is, so I could look up its definition. If you don't know either,
    you could add a print type(edge) to that method, and see what gets
    printed just before it gets the exception.

    That field might happen to be of type PHY_LINKS, in which case we see
    the initializer has the line
    self.SourceID = SourceID

    Unfortunately, we don't know what class that's supposed to be. You're
    using it like it's an integer, and the integer is apparently outside the
    range of the list PHY_NETWORK.nodes

    So you could add a few more print statements, find out the len() of
    nodes, and the value of SourceID.
    Dave Angel, May 14, 2014
  5. varun7rs

    varun7rs Guest

    That is a very descriptive post. Since its my first time programming I am not aware of many conventions that are being used to name classes. I tried to distinguish them by naming classes in caps. I borrowed some ideas from here and there to come up with the file. What I intend to dowith that file is basically define classes. I have defined all the classesthat are necessary for me. Now, the lower part of the file contains a function readXML or something which I am still working on but as of now it is not relevant. Second file would be the approach file which I have to use once I generate the xml file that I need to use. So, this brings me to the last file which is really messy.
    All I want to do in the file is that I'd like to pull out some data from the xml file(from the SNDLib website for the sake of topology). Since this xml file contains the source, destination and some other relevant attributes, I read them out of it. Now, I want to use the class PHY_NETWORK to create this topology. The class consists of arguments nodes, edges, etc., Here to add edges between the nodes, I call the method addEdge from the class PHY_NETWORK. But when I do that I get this error 'unicode' object has no attribute 'addInEdge. I'm not sure if I made myself clear. Once the stuff is working, I would like an xml file which looks somewhat like the one below but with attributes we need like the processing, storage and switching power.

    VNEInstance schema="VNEInstance.xsd" version="">
    <node capacity="975.4" costs="0.0" id="0" nodeName="0" xCoordinate="54" yCoordinate="41"/>
    <node capacity="742.5" costs="0.0" id="1" nodeName="1" xCoordinate="67" yCoordinate="33"/> I'm really sorry for the trouble but once I get this thing going then I can move on with the CPLEX solving stuff.Thanks alot for your help
    varun7rs, May 14, 2014
  6. The most commonly followed naming conventions in Python are those
    mandated for Python's own standard library. The definition of that is
    in a document called PEP 8:

    Makes a good read. If you at least mostly follow PEP 8, people on this
    list will instantly know what's a class and what's not, etc, and it'll
    make things easier all round.

    Chris Angelico, May 14, 2014
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