Estoy tratando de hacer un rastreador web que muestre una idea básica del rango de la página. Y el código para mí parece estar bien para mí, pero me devuelve errores e.x.

`Traceback (most recent call last):
  File "C:/Users/Janis/Desktop/WebCrawler/Web_crawler.py", line 89, in <module>
    webpages()
  File "C:/Users/Janis/Desktop/WebCrawler/Web_crawler.py", line 17, in webpages
    get_single_item_data(href)
  File "C:/Users/Janis/Desktop/WebCrawler/Web_crawler.py", line 23, in get_single_item_data
    source_code = requests.get(item_url)
  File "C:\Python34\lib\site-packages\requests\api.py", line 65, in get
    return request('get', url, **kwargs)
  File "C:\Python34\lib\site-packages\requests\api.py", line 49, in request
    response = session.request(method=method, url=url, **kwargs)
  File "C:\Python34\lib\site-packages\requests\sessions.py", line 447, in request
    prep = self.prepare_request(req)
  File "C:\Python34\lib\site-packages\requests\sessions.py", line 378, in prepare_request
    hooks=merge_hooks(request.hooks, self.hooks),
  File "C:\Python34\lib\site-packages\requests\models.py", line 303, in prepare
    self.prepare_url(url, params)
  File "C:\Python34\lib\site-packages\requests\models.py", line 360, in prepare_url
    "Perhaps you meant http://{0}?".format(url))
requests.exceptions.MissingSchema: Invalid URL '//www.hm.com/lv/logout': No schema supplied. Perhaps you meant http:////www.hm.com/lv/logout?`

y la última fila de código que Python me devuelve después de ejecutarlo es:

//www.hm.com/lv/logout

Tal vez el problema es con dos// pero estoy seguro, de todos modos, cuando intento rastrear otras páginas web e.x.http://en.wikipedia.org/wiki/Wiki me devuelveNone y los mismos errores.

    import requests
    from bs4 import BeautifulSoup
    from collections import defaultdict
    from operator import itemgetter

    all_links = defaultdict(int)

    def webpages():

            url = 'http://www.hm.com/lv/'
            source_code = requests.get(url)
            text = source_code.text
            soup = BeautifulSoup(text)
            for link in soup.findAll ('a'):
                href = link.get('href')
                print(href)
                get_single_item_data(href)
            return all_links

    def get_single_item_data(item_url):
        #if not item_url.startswith('http'):
            #item_url = 'http' + item_url
        source_code = requests.get(item_url)
        text = source_code.text
        soup = BeautifulSoup(text)
        for link in soup.findAll('a'):
            href = link.get('href')
            if href and href.startswith('http://www.'):
                if href:
                    all_links[href] += 1
                print(href)

    def sort_algorithm(list):
        for index in range(1,len(list)):
            value= list[index]
            i = index - 1
            while i>=0:
                if value < list[i]:
                    list[i+1] = list[i]
                    list[i] = value
                    i=i -1
                else:
                    break

    vieni = ["", "viens", "divi", "tris", "cetri", "pieci",
             "sesi", "septini", "astoni", "devini"]
    padsmiti = ["", "vienpadsmit", "divpadsmit", "trispadsmit", "cetrpadsmit",
             "piecpadsmit", 'sespadsmit', "septinpadsmit", "astonpadsmit", "devinpadsmit"]
    desmiti = ["", "desmit", "divdesmit", "trisdesmit", "cetrdesmit",
            "piecdesmit", "sesdesmit", "septindesmit", "astondesmit", "devindesmit"]



    def num_to_words(n):
        words = []
        if n == 0:
            words.append("zero")
        else:
            num_str = "{}".format(n)
            groups = (len(num_str) + 2) // 3
            num_str = num_str.zfill(groups * 3)
            for i in range(0, groups * 3, 3):
                h = int(num_str[i])
                t = int(num_str[i + 1])
                u = int(num_str[i + 2])
                print()
                print(vieni[i])
                g = groups - (i // 3 + 1)
                if h >= 1:
                    words.append(vieni[h])
                    words.append("hundred")
                    if int(num_str) % 100:
                        words.append("and")
                if t > 1:
                    words.append(desmiti[t])
                    if u >= 1:
                        words.append(vieni[u])
                elif t == 1:
                    if u >= 1:
                        words.append(padsmiti[u])
                    else:
                        words.append(desmiti[t])
                else:
                    if u >= 1:
                        words.append(vieni[u])

        return " ".join(words)

    webpages()

    for k, v in sorted(webpages().items(),key=itemgetter(1),reverse=True):
        print(k, num_to_words(v))