Trading using Python — Exponential Moving Average (EMA)

ema.py

# https://levelup.gitconnected.com/trading-using-python-exponential-moving-average-ema-f38ed3211a44?source=your_stories_page-------------------------------------

import re
import requests
from datetime import datetime


def cbpGetHistoricRates(market='BTC-GBP', granularity=86400, iso8601start='', iso8601end=''):
    if not isinstance(market, str):
        raise Exception('Market string input expected')

    if not isinstance(granularity, int):
        raise Exception('Granularity integer input expected')

    granularity_options = [60, 300, 900, 3600, 21600, 86400]
    if not granularity in granularity_options:
        raise Exception(
            'Invalid granularity: 60, 300, 900, 3600, 21600, 86400')

    if not isinstance(iso8601start, str):
        raise Exception('ISO8601 date string input expected')

    if not isinstance(iso8601end, str):
        raise Exception('ISO8601 date string input expected')

    # iso8601 regex
    regex = r'^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.[0-9]+)?(Z|[+-](?:2[0-3]|[01][0-9]):[0-5][0-9])?$'

    if len(iso8601start) < 0:
        match_iso8601 = re.compile(regex).match
        if match_iso8601(iso8601start) is None:
            raise Exception('iso8601 start date is invalid')

    if len(iso8601end) < 0:
        match_iso8601 = re.compile(regex).match
        if match_iso8601(iso8601end) is None:
            raise Exception('iso8601 end date is invalid')

    api = 'https://api.pro.coinbase.com/products/' + market + '/candles?granularity=' + \
        str(granularity) + '&start=' + iso8601start + '&end=' + iso8601end
    resp = requests.get(api)
    if resp.status_code != 200:
        raise Exception('GET ' + api + ' {}'.format(resp.status_code))
    data = {}
    for price in reversed(resp.json()):
        # time, low, high, open, close, volume
        iso8601 = datetime.fromtimestamp(price[0])
        timestamp = datetime.strftime(iso8601, "%d/%m/%Y %H:%M:%S")
        data[timestamp] = price[4]
    return data

# data: dictionary { 'dd/mm/yyy': price, 'dd/mm/yyyy': price, ... }
# num: range in the average calculation, normally 9 to 26


def exponentialMovingAverage(data, num):
    if not isinstance(data, dict):
        raise Exception('Dictionary input expected')

    if not isinstance(num, int):
        raise Exception('Integer input expected')

    if num < 9 or num > 26:
        raise Exception('Unusual numeric input detected')

    if (num > len(data)):
        raise Exception('Insufficient data for calculation')

    data_keys = list(data.keys())
    data_list = list(data.values())

    last_sma = -1
    result = {}
    for x in range(len(data_list) - num + 1):
        series = data_list[x:x + num]

        if (last_sma == -1):
            result[data_keys[x + num - 1]] = round((sum(series) / num), 2)
        else:
            current_price = data[data_keys[x + num - 1]]
            result[data_keys[x + num - 1]] = round(
                current_price * 2 / (num + 1) + last_sma * (1 - 2 / (num + 1)), 2)

        last_sma = result[data_keys[x + num - 1]]

    return result


data = cbpGetHistoricRates('BTC-GBP', 86400)
ema12 = exponentialMovingAverage(data, 12)
ema26 = exponentialMovingAverage(data, 26)


def csvResults():
    print('date,price,ema12,ema26')
    data_keys = list(data.keys())
    for key in data_keys:
        price = 0
        if key in data:
            price = data[key]
        ema12r = 0
        if key in ema12:
            ema12r = ema12[key]
        ema26r = 0
        if key in ema26:
            ema26r = ema26[key]

        if ema26r != 0:
            print(key + ',' + str(price) + ',' +
                  str(ema12r) + ',' + str(ema26r))


csvResults()