from datetime import datetime
import time, pytz

import requests
from lxml import html

import matplotlib.pyplot as plt
import pandas as pd

session = requests.Session()
url = 'https://coinmarketcap.com/all/views/all/'
response = session.get(url).text
etree = html.fromstring(response)
slugs = etree.xpath('//tr/td[2]/a/@href')
market_caps = {}
for slug in slugs:
    print(slug)
    url = 'https://coinmarketcap.com{}historical-data/?start=20130428&end={}{:02d}{:02d}'.format(slug,*datetime.now(pytz.utc).timetuple())
    try:
        response = session.get(url).text.replace(',','').replace('-','')
    except Exception as e:
        print(e)
        continue
    etree = html.fromstring(response)
    data = zip(*[[x.text for x in etree.xpath('//table/tbody/tr/td[{}]'.format(col))] for col in range(1,8)])
    for date,open_value,high_value,low_value,close_value,volume_value,market_cap_value in data:
        date = datetime.strptime(date,'%b %d %Y')
        try:
            market_caps[date]
        except KeyError:
            market_caps[date] = {}
        try:
            market_caps[date][slug[12:-1]] = int(market_cap_value)
        except Exception as e:
            print(e)
    time.sleep(3)

rank = pd.DataFrame.from_dict(market_caps,orient='index').rank(axis=1,ascending=False)
rank = rank['0x'].loc['2017-08-16':]
rank.plot()
plt.savefig('output.pdf')