A simple currency board tracker for For-Ex.

forex.py

#!/usr/bin/env python3
# A simple currency board tracker for For-Ex.
# Needs `pip3 install colorama` and normal Python3.
from collections import defaultdict
from colorama import Fore, Style
import os

currency = {
        'GBP': Fore.RED,
        'EUR': Fore.BLUE,
        'USD': Fore.GREEN,
        'CHF': Fore.MAGENTA,
        'JPY': Fore.WHITE,
        'CAD': Style.DIM + Fore.YELLOW,
        'CNY': Style.NORMAL + Fore.YELLOW,
        }

# Initial exchange rates, as counters on the table.
init = [
        ('GBP', 1, 'EUR'),
        ('GBP', 1, 'CHF'),
        ('GBP', 1, 'JPY'),
        ('GBP', 2, 'CAD'),
        ('GBP', 6, 'CNY'),

        ('EUR', 1, 'JPY'), ('EUR', 1, 'CAD'), ('EUR', 5, 'CNY'),
        ('USD', 1, 'JPY'), ('USD', 1, 'CAD'), ('USD', 5, 'CNY'),
        ('CHF', 1, 'JPY'), ('CHF', 1, 'CAD'), ('CHF', 5, 'CNY'),
        ('JPY', 1, 'CAD'), ('JPY', 4, 'CNY'),
        ('CAD', 3, 'CNY'),
        ]


def main(args):
    exchange = defaultdict(lambda: defaultdict(int))
    for (a, x, b) in init:
        exchange[a][b] = x
        exchange[b][a] = -x

    while True:
        os.system('cls||clear')
        board(exchange)
        print()
        print('Strengthen(+) // Weaken(-) + Currency (+USD // -GBP)')
        arg = input('> ').strip()
        d, self = arg[0], arg[1:].strip().upper()
        if d not in '-+' or self not in currency: continue
        d = 1 if d == '+' else -1
        for other in currency:
            val = exchange[self][other]
            val += d

            # Clamp to the extremes.
            val = max(-10, min(10, val))

            # Skip zero -> 1:1 has two spaces.
            if val == 0: val = d

            # Denormalize to both exchange rates.
            exchange[self][other] = val
            exchange[other][self] = -val


def board(exchange):
    cell = '{:^5}'
    fmt = lambda name: currency[name] + cell.format(name) + Style.RESET_ALL

    table = '{:^5} : {:^5} | {:^5} | {:^5} | {:^5} | {:^5} | {:^5} | {:^5} | {:^5}'
    print(table.format('$', 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8))
    for self in currency:
        print('-' * 70)

        # Fill out the row of weaker currencies.
        row = [[], [], [], [], [], [], [], []]
        for other in currency:
            if self is other: continue
            i = exchange[self][other] - 1
            if i < 0: continue
            row[i].append(other)

        # Print rows one at a time.
        empty = True
        for i in range(len(currency)):
            inner = [fmt(col[i]) if i < len(col) else '     ' for col in row]
            line = ' | '.join([fmt(self)] + inner)
            if ''.join(inner).strip() == '':
                if empty: print(line)
                break # no more rows to print
            print(line)
            empty = False


if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser()
    main(parser.parse_args())