Question

I do atomistic modelling, and use Python to analyze simulation results. To simplify work with a whole bunch of Python scripts used for different tasks, I decided to write simple GUI to run scripts from it.

I have a (rather complex) directory structure beginning from some root (say ~/calc), and I want to populate wx.TreeCtrl control with directories containing calculation results preserving their structure. The folder contains the results if it contains a file with .EXT extension. What i try to do is walk through dirs from root and in each dir check whether it contains .EXT file. When such dir is reached, add it and its ancestors to the tree:

def buildTree(self, rootdir):
    root = rootdir
    r = len(rootdir.split('/'))
    ids = {root : self.CalcTree.AddRoot(root)}
    for (dirpath, dirnames, filenames) in os.walk(root):
        for dirname in dirnames:
            fullpath = os.path.join(dirpath, dirname)
            if sum([s.find('.EXT') for s in filenames]) > -1 * len(filenames):
                ancdirs = fullpath.split('/')[r:]
                ad = rootdir
                for ancdir in ancdirs:
                    d = os.path.join(ad, ancdir)
                    ids[d] = self.CalcTree.AppendItem(ids[ad], ancdir)
                    ad = d

But this code ends up with many second-level nodes with the same name, and that’s definitely not what I want. So I somehow need to see if the node is already added to the tree, and in positive case add new node to the existing one, but I do not understand how this could be done. Could you please give me a hint?

Besides, the code contains 2 dirty hacks I’d like to get rid of:

1. I get the list of ancestor dirs with splitting the full path in \
   positions, and this is Linux-specific;

2. I find if .EXT file is in the directory by trying to find the extension in the strings from filenames list, taking in account that s.find returns -1 if the substring is not found.

Is there a way to make these chunks of code more readable?

Answer 1

First of all the hacks:

1. To get the path seperator for whatever os your using you can use os.sep.

2. Use str.endswith() and use the fact that in Python the empty list [] evaluates to False:

   if [ file for file in filenames if file.endswith('.EXT') ]:

In terms of getting them all nicely nested you’re best off doing it recursively. So the pseudocode would look something like the following. Please note this is just provided to give you an idea of how to do it, don’t expect it to work as it is!

def buildTree(self, rootdir):
    rootId = self.CalcTree.AddRoot(root)

    self.buildTreeRecursion(rootdir, rootId)

def buildTreeRecursion(self, dir, parentId)
    # Iterate over the files in dir
    for file in dirFiles: 
        id = self.CalcTree.AppendItem(parentId, file) 

        if file is a directory:
            self.buildTreeRecursion(file, id)

Hope this helps!