Compute dynamically avg. price of an item on Leboncoin.fr based on the 100 first items, using Python 3 and Request

leboncoin_avgprice.py

#!/usr/bin/python3
# coding: utf-8

import requests
from bs4 import BeautifulSoup
from scrapy import Selector
import datetime
import argparse


def compute_avg(keyword):
    """
    Export all price from a keyword on leboncoin.fr,
    then compute average price for 100 items (or less if no available).

    Arguments:
         keyword (str):
            keyword you would type on leboncoin search browser to get access to your items
    Return:
        average price (€)
    """

    # INITIALISATION
    print('-- INITIALISATION --')
    print('KEYWORD: {}'.format(keyword))
    print('SITE: LEBONCOIN.FR')
    r = requests.session()
    start = datetime.datetime.now()
    price_table = []
    base_url = 'https://www.leboncoin.fr/recherche/?text='
    page_nb = 1
    url_to_start = base_url + keyword.replace(' ', '%20') + "&page={}".format(page_nb)
    response = r.get(url=url_to_start)
    soup = BeautifulSoup(response.text, features='html.parser')
    sel = Selector(text=soup.prettify())

    # CRAWLING ET PARSEING
    while len(price_table) < 100:
        if response.status_code == 200:
            print('PAGE: {}'.format(page_nb))
            prices = \
                [float(x.strip().replace(' ', '')) for x in sel.xpath("//span[@itemprop='price']/text()").extract()]
            price_table.extend(prices)
            print(price_table)
            page_nb += 1
            url_to_follow = base_url + keyword.replace(' ', '%20') + "&page={}".format(page_nb)
            print(url_to_follow)
            response = r.get(url=url_to_follow)
        else:
            print('Page #{} : inaccessible'.format(page_nb))
            break

    # TEMPS PASSE
    end = datetime.datetime.now()
    time_elapsed = str(end - start)
    print('\n')
    print('-- TIME ELAPSED --')
    print(time_elapsed)

    avg_price = sum(price_table)/float(len(price_table))
    return avg_price

if __name__ == "__main__":

    argparser = argparse.ArgumentParser()
    argparser.add_argument('keyword', help='Search Keyword on Leboncoin.fr')

    args = argparser.parse_args()
    keyword = args.keyword
    avg_price = compute_avg(keyword)

    if avg_price:
        print("Le prix moyen pour le mot-clé '{}' sur leboncoin.fr est de: ".format(keyword)
              + '\n' + "{:.2f}".format(avg_price) + ' €')
    if not avg_price:
        print('Prix indisponible, veuillez réessayer')