21

I decided that I'll learn Python tonight :) I know C pretty well (wrote an OS in it), so I'm not a noob in programming, so everything in Python seems pretty easy, but I don't know how to solve this problem: let's say I have this address:

http://example.com/random/folder/path.html

Now how can I create two strings from this, one containing the "base" name of the server, so in this example it would be

http://example.com/

and another containing the thing without the last filename, so in this example it would be

http://example.com/random/folder/

Also I of course know the possibility to just find the third and last slash respectively, but is there a better way?

Also it would be cool to have the trailing slash in both cases, but I don't care since it can be added easily. So is there a good, fast, effective solution for this? Or is there only "my" solution, finding the slashes?

4
  • You might want to share your solution in code. Commented Jan 16, 2009 at 7:49
  • 2
    Come back tomorrow and let us know how that's going for you. I suspect you'll just be writing C code in Python rather than real Python code :-). Commented Jan 16, 2009 at 7:55
  • 4
    Since you mention it, which OS have you written? Commented Jan 16, 2009 at 13:01
  • You can find a Python regex for a partial split (i.e. URL, scheme, domain, TLD, port and query path) here: stackoverflow.com/questions/9760588/… Commented Aug 11, 2015 at 21:19

6 Answers 6

60

The urlparse module in Python 2.x (or urllib.parse in Python 3.x) would be the way to do it.

>>> from urllib.parse import urlparse
>>> url = 'http://example.com/random/folder/path.html'
>>> parse_object = urlparse(url)
>>> parse_object.netloc
'example.com'
>>> parse_object.path
'/random/folder/path.html'
>>> parse_object.scheme
'http'
>>>

If you wanted to do more work on the path of the file under the URL, you can use the posixpath module:

>>> from posixpath import basename, dirname
>>> basename(parse_object.path)
'path.html'
>>> dirname(parse_object.path)
'/random/folder'

After that, you can use posixpath.join to glue the parts together.

Note: Windows users will choke on the path separator in os.path. The posixpath module documentation has a special reference to URL manipulation, so all's good.

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5 Comments

+1 on urlparse, but don't use os.path to manipulate the .path part. os.path's handling necessarily differs from OS to OS, whereas URIs always use '/' as the path part separator.
yeah, remove the os.path part. Maybe use the posixpath module instead. Then you'll have my vote.
argh, missed that one completely. It's been ages since I used windows :|. Fixed.
Just for ease of reference, here is the procedure for Py 2 : import urlparse; parse_object = urlparse.urlparse(url)
"windows users will choke on ..." I like to think of it as Linux users will choke on the path specifier that was around before it was :)
12

If this is the extent of your URL parsing, Python's inbuilt rpartition will do the job:

>>> URL = "http://example.com/random/folder/path.html"
>>> Segments = URL.rpartition('/')
>>> Segments[0]
'http://example.com/random/folder'
>>> Segments[2]
'path.html'

From Pydoc, str.rpartition:

Splits the string at the last occurrence of sep, and returns a 3-tuple containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, return a 3-tuple containing two empty strings, followed by the string itself

What this means is that rpartition does the searching for you, and splits the string at the last (right most) occurrence of the character you specify (in this case / ). It returns a tuple containing:

(everything to the left of char , the character itself , everything to the right of char)

3 Comments

I know everyone says (with good reasons) to use a library like urllib for things like this but I have an emotional preference for this approach in cases like this. As far as I can see this will be fully reliable. There's no fancy parsing required for this limited case. As long as the incoming URL is well formed it should be guaranteed that the path starts at the third slash character. I am drawn to this because it looks simpler and faster without the library import, but I'm ready to be corrected if I'm wrong.
The Pydoc link is broken (404).
What is 'sep'? A simple (fixed) string? A regular expression?
10

I have no experience with Python, but I found the urlparse module, which should do the job.

Comments

8

In Python, a lot of operations are done using lists. The urlparse module mentioned by Sebasian Dietz may well solve your specific problem, but if you're generally interested in Pythonic ways to find slashes in strings, for example, try something like this:

url = 'http://example.com/random/folder/path.html'

# Create a list of each bit between slashes
slashparts = url.split('/')

# Now join back the first three sections 'http:', '' and 'example.com'
basename = '/'.join(slashparts[:3]) + '/'

# All except the last one
dirname = '/'.join(slashparts[:-1]) + '/'

print 'slashparts = %s' % slashparts
print 'basename = %s' % basename
print 'dirname = %s' % dirname

The output of this program is this:

slashparts = ['http:', '', 'example.com', 'random', 'folder', 'path.html']
basename = http://example.com/
dirname = http://example.com/random/folder/

The interesting bits are split, join, the slice notation array[A:B] (including negatives for offsets-from-the-end) and, as a bonus, the % operator on strings to give printf-style formatting.

Comments

2

It seems like the posixpath module mentioned in sykora's answer is not available in my Python setup (Python 2.7.3).

As per this article, it seems that the "proper" way to do this would be using...

  • urlparse.urlparse and urlparse.urlunparse can be used to detach and reattach the base of the URL
  • The functions of os.path can be used to manipulate the path
  • urllib.url2pathname and urllib.pathname2url (to make path name manipulation portable, so it can work on Windows and the like)

So for example (not including reattaching the base URL)...

>>> import urlparse, urllib, os.path
>>> os.path.dirname(urllib.url2pathname(urlparse.urlparse("http://example.com/random/folder/path.html").path))
'/random/folder'

1 Comment

The doughellmann.com link is broken: "404. Page Not Found"
1

You can use Python's library furl:

f = furl.furl("http://example.com/random/folder/path.html")
print(str(f.path))  # '/random/folder/path.html'
print(str(f.path).split("/")) # ['', 'random', 'folder', 'path.html']

To access word after first "/", use:

str(f.path).split("/") # 'random'

1 Comment

Re "Python's library": But not part of the batteries(?)

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