cryptodata.py

import os
import csv
import json
import re
from datetime import datetime
from urllib.request import urlopen
from urllib.parse import urlencode

os.chdir(os.path.dirname(__file__))

def cryptodata(
    pair=None,
    from_date=datetime(2000, 1, 1),
    to_date=datetime.now(),
    period=7200):
    """
    pair: "BTC-ETH", "BTC-LTC", "USDT-ETH"
    from_date: datetime(2012, 1, 1) # defaults to Jan 1, 2000
    to_date: datetime(2017, 6, 21)
    period: 86400 (in seconds; minimum of 7200)
    """
    if not pair:
        raise TypeError("Expected pair to be a currency pair, got None")
    match = re.match(r"^([A-Za-z]{1,4}).([A-Za-z]{1,4})$", pair)
    if match is None:
        raise ValueError(f"{pair} was not in the proper format")
    currency_pair = "_".join((match.group(1), match.group(2))).upper()
    start = datetime.timestamp(from_date)
    end = datetime.timestamp(to_date)
    formdata = urlencode({
        "command": "returnChartData",
        "currencyPair": currency_pair,
        "start": start,
        "end": end,
        "period": period
    })
    req = urlopen("https://poloniex.com/public?" + formdata)
    data = json.load(req)
    if "error" in data:
        raise ValueError(data["error"])
    return data


def data_to_csv(data, filename=None):
    """
    data: from the cryptodata function
    filename: "BTC_ETH_24h_all_time.csv"
    """
    if not filename:
        raise TypeError("Expected a filename, got None")
    cols = list(data[0].keys())
    with open(os.path.join(os.getcwd(), filename), "w") as f:
        w = csv.writer(f)
        w.writerow(cols)
        for datum in data:
            w.writerow([datum[col] for col in cols])
    return True