On Sun, Sep 12, 2010 at 10:48 AM, Roelof Wobben <rwob...@hotmail.com> wrote:
> > > > ________________________________ > > Date: Sun, 12 Sep 2010 09:46:08 -0400 > > From: joel.goldst...@gmail.com > > To: tutor@python.org > > Subject: Re: [Tutor] tree problem > > > > > > > > On Sun, Sep 12, 2010 at 9:32 AM, Roelof Wobben > >> wrote: > > > > > > ________________________________ > >> Date: Sun, 12 Sep 2010 09:08:18 -0400 > >> From: joel.goldst...@gmail.com > >> To: tutor@python.org > > > >> Subject: Re: [Tutor] tree problem > >> > >> > >> > >> On Sun, Sep 12, 2010 at 7:54 AM, Lie Ryan > >>> wrote: > >> On 09/12/10 21:15, Roelof Wobben wrote: > >>> > >>> > >>> Hello, > >>> > >>> I have this problem. > >>> > >>> Write a program named litter.py that creates an empty file named > >> trash.txt in each subdirectory of a directory tree given the root of > >> the tree as an argument (or the current directory as a default). > >> > >> By default, Python has a recursion limit of 1000 deep; that is, your > >> function is calling itself 1000 times without returning. > >> > >> In this case, the only reason why you hit the recursion limit is if you > >> have a directory which is 1000 deep (quite unlikely, Windows has a > >> directory depth limit much lower than that). > >> > >> Or your function somehow never returns, in a typical recursive function, > >> it's usually because you have problem in the precondition. > >> > >> You really have two problems here: > >> > >> 1. You need to know how to write an empty file with the name > >> litter.py. You should probably write a function to see if you can do > >> that. That's pretty easy > >> > >> 2. You need to traverse a tree. I see you are using os module. You > >> should try help(os) while in your python shell to learn what methods > >> are available. Traversing a tree is also sometimes called 'walking' > >> > >> good luck > >> > >> > >> -- > >> Joel Goldstick > >> > >> > >> _______________________________________________ Tutor maillist - > > > >> Tutor@python.org To unsubscribe or change > > subscription options: > >> http://mail.python.org/mailman/listinfo/tutor > > > > Hello Joel. > > > > Youre right. > > Problem 1 is easily solved by using myfile = open ('filename', 'w') > > followed by myfile.close() > > > > Problem 2 is more difficult. > > > > I have to use recursion and as example the source of the tree command > > in linux is given. > > The traverse module looks like this : > > > > def traverse(path, prefix='|--', s='.\n', f=0, d=0): > > > > what's up with the prefix??? > > > > dirlist = getdirlist(path) > > for num, file in enumerate(dirlist): > > > > why are you using enumerate? it gives you num which you never use > > for file in dirlist gives what you seem to be using > > lastprefix = prefix[:-3] + '``--' > > dirsize = len(dirlist) > > if num < dirsize - 1: > > s += '%s %s\n' % (prefix, file) > > else: > > s += '%s %s\n' % (lastprefix, file) > > path2file = os.path.join(path, file) > > > > if os.path.isdir(path2file): > > d += 1 > > if getdirlist(path2file): > > s, f, d = traverse(path2file, '| ' + prefix, s, f, d) > > else: > > f += 1 > > return s, f, d > > > > For me it looks like the pathfile = os.path.join(path, file) > > and then the s.f.d. rule take care that a subdir is entered. > > what are s.f.d. Can you use more descriptive names > > > > Am I right on this ? > > > > Roelof > > > > > > > > > > > > -- > > Joel Goldstick > > > > > > _______________________________________________ Tutor maillist - > > Tutor@python.org To unsubscribe or change subscription options: > > http://mail.python.org/mailman/listinfo/tutor > > Hello, > > I solved this by this programm : > > import os > import sys > > def getroot(): > if len(sys.argv) == 1: > path = '' > else: > path = sys.argv[1] > if os.path.isabs(path): > tree_root = path > else: > tree_root = os.path.join(os.getcwd(), path) > return tree_root > > def getdirlist(path): > dirlist = os.listdir(path) > dirlist = [name for name in dirlist if name[0] != '.'] > dirlist.sort() > return dirlist > > def traverse(path, s='.\n', f=0, d=0): > file = os.path.join(path,'trash.txt') > myfile = open (file, 'w') > myfile.close() > dirlist = getdirlist(path) > for num, file in enumerate(dirlist): > dirsize = len(dirlist) > if num < dirsize - 1: > s += '%s \n' % (file) > else: > s += '%s \n' % (file) > path2file = os.path.join(path, file) > if os.path.isdir(path2file): > d += 1 > s, f, d = traverse(path2file, '| ' + s, f, d) > return s,f,d > > if __name__ == '__main__': > root = getroot() > tree_str, files, dirs = traverse(root) > > > Roelof > > Good for you. Some questions: What do you mean to be happening here: if num < dirsize - 1: s += '%s \n' % (file) else: s += '%s \n' % (file) it does the same thing in either case What exactly does s do for you? You use the first parameter 'path' in your calls to traverse, but I don't see how you are using f or d anywhere either -- Joel Goldstick
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