recursive file editing

[Peter Otten]

TaeKyon wrote:

> Il Sat, 03 Apr 2004 17:22:04 -0800, Josiah Carlson ha scritto:
> 
>> for thing in os.walk('mydir'):
>>      filehandle = file(thing, 'r+')
> 
> I'm such a newbe I can't get it to work. Here is an example:
> 
> in empty directory foo I touch a b c d;
> suppose I want to write "This works !" in each of these files.
> 
> I run python
>>>> import os
>>>> for thing in os.walk('foo'):
> ...     thingopen = file(thing,'r+')
> ...     thingopen.write("This works !")
> ...     thingopen.close()
> ...
> Traceback (most recent call last):
>   File "<stdin>", line 2, in ?
> TypeError: coercing to Unicode: need string or buffer, tuple found
> 
> And in fact:
> 
>>>> for thing in os.walk('foo'):
> ...     print thing
> ...
> ('foo', [], ['a', 'b', 'c', 'd'])
> 
> which is a tuple, I suppose.
> 
> Selecting thing[2] doesn't help, because it now complains of it being a
> list.
> 
> In the end I get this to work:
> 
> for filetuple in os.walk('foo'):
> ...     for filename in filetuple[2]:
> ...         fileopen = file(filename, 'r+')
>             fileopen.write("This works !")
>             fileopen.close()
> 
> which seems a bit of a clumsy way to do it.
> And besides it only works if I run python from directory foo,
> otherwise it tells me "no such file or directory".

A minimal working example is:

import os
for path, folders, files in os.walk("/path/to/folder"):
    for name in files:
        filepath = os.path.join(path, name)
        fileopen = file(filepath, 'r+')
        fileopen.write("This works !")
        fileopen.close()

You need to compose the filepath, and, yes, it's a bit clumsy.
I've written a little generator function to hide some of the clumsiness:

def files(folder):
    for path, folders, files in os.walk(folder):
        for name in files:
            yield os.path.join(path, name)

With that the code is simplified to:

for filepath in files("/path/to/folder"):
    fileopen = file(filepath, 'r+')
    fileopen.write("This works !")
    fileopen.close()

HTH,
Peter