Finance

LedgerMan implements some core classes that help you interact with finances.

Money

For finanial calculations, the Money class is very useful:

m1 = Money() # default: 0 EUR
m2 = Money("10 USD")

You can set a precision (how many digits behind the separator are stored) for money objects. If you don't, LedgerMan will choose a common precision for your currency.

m3 = Money("10 BTC", precision=8)

Do basic calculations with Money:

m = Money("20 EUR")

m += Money("5 EUR")
m += Money("5 EUR")

m /= 2
m -= Money("5 EUR")
m == Money("10 EUR") # true

m - Money("20 ETH") # ERROR - you can't add different currencies

Exchange Rates

Exchanging Money

Whenever you want to work with multiple currencies, you likely want to convert them:

m = Money("20 EUR")
e = ExchangeRate("EUR", "USD", 1.17) # from 2020-10-15

e.convert(m) # 23.4 USD

Just add common exchange rates so you can add money objects of different currencies:

# Add exchange rate
Money.insertExchangeRate("EUR", "ETH", 0.0031) # from 2020-10-15

Money.canConvert("EUR", "ETH") # Check: true

m = Money("5 ETH")
m.to("EUR") # 1612.90 EUR

m = Money("5 ETH") + Money("200 EUR") # 5.62 ETH

The more exchange rates with already known conversions you add, the more conversions you can perform:

Money.insertExchangeRate("EUR", "ETH", 0.0031) # from 2020-10-15
Money.insertExchangeRate("EUR", "USD", 1.17) # from 2020-10-15

Money.canConvert("EUR", "USD") # true; Both exchangeRates are used.

m = Money("5 ETH")
m.to("USD")

m = Money("5 ETH") + Money("200 USD")

Exchange-Rate APIs

You can fetch exchange rates from the following APIs:

api	assets	refresh-rates
ECB (European Central Bank)	Common currencies - USD, JPY, BGN, CZK, DKK, GBP, HUF, PLN, RON, SEK, CHF, ISK, NOK, HRK, RUB, TRY, AUD, BRL, CAD, CNY, HKD, IDR, ILS, INR, KRW, MXN, MYR, NZD, PHP, SGD, THB, ZAR	daily around 16:30
Bitpanda	Crypto - BTC, BCI5, BEST, PAN, BCI10, BCI25, XAU, ETH, LINK, USDT, MIOTA, XRP, ADA, TRX, VET, OMG, NEO, QTUM, LTC, XEM, XTZ, XAG, YFI, CHZ, XLM, ONT, BCH, USDC, EOS, UNI, WAVES, ATOM, DOT, SNX, DASH, ZRX, BAT, KMD, ETC, DOGE, ZEC, XPD, REP, LSK, COMP, XPT, MKR, FIL, BAND, KNC, AAVE, UMA, REN	A few times per second
CoinGecko	Common crypto - eth, btc, ltc, trx, usdt, xrp, link, best, pan, miota, ada, vet, omg, neo, qtum, xem, xtz, yfi, chz, xlm, ont, bch, usdc, eos, uni, waves, atom, dot, snx, dash, zrx, bat, kmd, etc, doge, zec, rep, lsk, comp, mkr	every few seconds

Fetch rates from an API and just use the fetched conversions implicitly when doing money operations (+ - * /):

The European central Bank:

# default: European Central Bank
Money.fetchRates()

# will print all fetched rates (here: ecb)
Money.fetchRates(verbose=True)

# fetch from the European Central Bank (equal)
Money.fetchRates("ecb")

m = Money("5 EUR") + Money("5 USD") + Money("5 CHF") # no error

Bitpanda:

# fetch crypto from Bitpanda
Money.fetchRates("bitpanda")

m = Money("5 EUR") + Money("5 ETH") + Money("5 LTC") # no error

CoinGecko:

# fetch crypto from CoinGecko
Money.fetchRates("coingecko")

m = Money("5 EUR") + Money("5 ETH") + Money("5 LTC") # no error

Note that the APIs may not be reliable all the time and that you will need a network connection.