Python master task

currencies.py

# -*- coding: utf-8 -*-
__author__ = 'diony_000'

#original list of currencies is from https://code.google.com/p/dspl/source/browse/datasets/google/canonical/currencies.csv

symbol_to_currency = {
    '$':['USD','AUD','ARS','BBD','BMD','BND','BSD','CAD','CLP','COP','FJD','GYD','HKD','KYD','LRD','MXN','NZD','SBD','SGD','SRD','SVC','XCD'],
    '$b':['BOB'],
    '$U':['UYU'],
    '£':['GBP','EGP','FKP','GIP','LBP','SHP','SYP'],
    '¥':['CNY','JPY'],
    '؋':['AFN'],
    '฿':['THB'],
    '៛':['KHR'],
    '₡':['CRC'],
    '₦':['NGN'],
    '₩':['KPW','KRW'],
    '₪':['ILS'],
    '₫':['VND'],
    '€':['EUR'],
    '₭':['LAK'],
    '₮':['MNT'],
    '₱':['CUP'],
    '₴':['UAH'],
    '₨':['LKR','MUR','NPR','PKR','SCR'],
    '﷼':['IRR','OMR','QAR','SAR','YER'],
    'B/.':['PAB'],
    'Bs':['VEF'],
    'BZ$':['BZD'],
    'C$':['NIO'],
    'Ft':['HUF'],
    'ƒ':['ANG','AWG'],
    'Gs':['PYG'],
    'CHF':['CHF'],
    'J$':['JMD'],
    'Kč':['CZK'],
    'KM':['BAM'],
    'kn':['HRK'],
    'kr':['DKK','ISK','NOK','SEK'],
    'L':['HNL'],
    'lei':['RON'],
    'Lek':['ALL'],
    'Ls':['LVL'],
    'Lt':['LTL'],
    'MT':['MZN'],
    'NT$':['TWD'],
    'P':['BWP'],
    'p.':['BYR'],
    'Php':['PHP'],
    'Q':['GTQ'],
    'R':['ZAR'],
    'R$':['BRL'],
    'RD$':['DOP'],
    'RM':['MYR'],
    'Rp':['IDR'],
    'S':['SOS'],
    'S/.':['PEN'],
    'TL':['TRY'],
    'TT$':['TTD'],
    'zł':['PLN'],
    'ден':['MKD'],
    'Дин.':['RSD'],
    'лв':['BGN','KGS','KZT','UZS'],
    'ман':['AZN'],
    'руб':['RUB']
}

currency_converter.py

# -*- coding: utf-8 -*-
__author__ = '[email protected]'

import argparse
from currencies import symbol_to_currency
from json import dumps
from lxml import etree

yahoo_api_url = 'http://query.yahooapis.com/v1/public/yql?q=select * from yahoo.finance.xchange where pair in ("%s")&env=store://datatables.org/alltableswithkeys'
exchange_rate_type = 'Ask' #or Bid
all_currencies = [code for codes in symbol_to_currency.values() for code in codes]

def parse_currency(currency):
    result = currency
    if result not in all_currencies:
        try:
            result = symbol_to_currency[currency]
            if len(result) > 1:
                while True:
                    print('There are multiple (%d) currencies with this symbol "%s". Please choose the correct currency code from this list:' % (len(result), currency))
                    for currency_option in result:
                        print('%s' % (currency_option, ))
                    currency_option = input('Enter your currency code:')
                    if currency_option in result:
                        result = currency_option
                        break
                    else:
                        print('It seems you entered incorrect currency, lets try again!')
        except KeyError:
            print('Currency "%s" does not exist.' % currency)
            raise
    return result


def convert_amount(amount, input_currency, output_currency=None):
    try:
        amount = float(amount)
    except ValueError:
        print('Amount has to be a float number.')
        raise

    input_currency = parse_currency(input_currency)
    if output_currency:
        output_currency = [parse_currency(output_currency)]
    else:
        output_currency = all_currencies

    currency_pairs = [input_currency+currency for currency in output_currency]
    root = etree.parse(yahoo_api_url % '", "'.join(currency_pairs)).getroot()
    output = {'output':{}}

    for currency_pair in currency_pairs:
        exchange_rate = float(root.find('results/rate[@id="%s"]/%s' % (currency_pair, exchange_rate_type)).text)
        output['output'][currency_pair[3:]] = round(exchange_rate * amount, 2)

    output['input'] = {'amount': amount, 'currency': input_currency}
    return dumps(output, sort_keys=True, indent=4, separators=(',', ': '))

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Converts currency with use of public Yahoo Finance API.')
    parser.add_argument('--amount', required=True, type=float, help='Amount to be converted.')
    parser.add_argument('--input_currency', required=True, help='Currency of amount.')
    parser.add_argument('--output_currency', help='Desired currency to convert to. If omitted, converts to all currencies.')
    args = parser.parse_args()

    print(convert_amount(amount=args.amount, input_currency=args.input_currency, output_currency=args.output_currency))