Easy Money

`py_simple.easy_money`

easy_money formats prices and splits bills without the decimal boilerplate.

`EasyMoneyError`

Bases: Exception

Raised when a money calculation cannot be completed.

Parameters:

Name	Type	Description	Default
`message`	`str`	Description of what went wrong.	required

`add_tax(amount, rate)`

Add a tax rate to an amount and round to cents.

Parameters:

Name	Type	Description	Default
`amount`		The price before tax.	required
`rate`	`float`	Tax rate as a percent, such as `8.5` for 8.5%.	required

Returns:

Name	Type	Description
`Decimal`	`Decimal`	The price after tax, rounded to two decimal places.

Raises:

Type	Description
`EasyMoneyError`	If `amount` or `rate` is not a number, or if `rate` is negative.

Example

The Py_simple WayThe Traditional Way

from py_simple import add_tax

total = add_tax(10, 8.5)

from decimal import Decimal, ROUND_HALF_UP

total = (Decimal("10") * (1 + Decimal("8.5") / 100)).quantize(
    Decimal("0.01"), rounding=ROUND_HALF_UP
)

`calculate_discount(amount, discount_rate)`

Calculate the price after applying a percentage discount.

Parameters:

Name	Type	Description	Default
`amount`		The original price before the discount.	required
`discount_rate`	`float`	Discount percentage, such as `15` for 15%.	required

Returns:

Name	Type	Description
`Decimal`	`Decimal`	The discounted price, rounded to two decimal places.

Raises:

Type	Description
`EasyMoneyError`	If the amount or discount rate is invalid, or if the discount rate is outside the range of 0 to 100.

Example

The Py_simple WayThe Traditional Way

from py_simple import calculate_discount

discounted_price = calculate_discount(2000, 15)

from decimal import Decimal, ROUND_HALF_UP

amount = Decimal("2000")
discount_rate = Decimal("15")
discounted_price = (amount * (1 - discount_rate / 100)).quantize(
    Decimal("0.01"), rounding=ROUND_HALF_UP
)

`calculate_tip(amount, tip_rate)`

Calculate the tip amount for a bill given a percentage rate.

Parameters:

Name	Type	Description	Default
`amount`		The bill amount before tip.	required
`tip_rate`	`float`	Tip percentage, such as `15` or `20` for 15% or 20%.	required

Returns:

Name	Type	Description
`Decimal`	`Decimal`	The tip amount to add, rounded to two decimal places.

Raises:

Type	Description
`EasyMoneyError`	If `amount` or `tip_rate` is not a valid number, or if `tip_rate` is negative.

Example

The Py_simple WayThe Traditional Way

from py_simple import calculate_tip

tip = calculate_tip(50, 18)

from decimal import Decimal, ROUND_HALF_UP

bill = Decimal("50")
rate = Decimal("18")
tip = (bill * (rate / Decimal(100))).quantize(
    Decimal("0.01"), rounding=ROUND_HALF_UP
)

`format_money(amount, symbol='$')`

Format a number as money with two decimal places.

Parameters:

Name	Type	Description	Default
`amount`		The amount to format.	required
`symbol`	`str`	Currency symbol placed before the number. Defaults to `"$"`.	`'$'`

Returns:

Name	Type	Description
`str`	`str`	The formatted amount, such as `"$12.50"`.

Raises:

Type	Description
`EasyMoneyError`	If `amount` is not a number.

Example

The Py_simple WayThe Traditional Way

from py_simple import format_money

print(format_money(12.5))

from decimal import Decimal, ROUND_HALF_UP

cents = Decimal("12.5").quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
print(f"${cents}")

`split_bill(total, people)`

Split a bill evenly and round each share to cents.

Parameters:

Name	Type	Description	Default
`total`		The full bill.	required
`people`	`int`	How many people are paying. Must be at least 1.	required

Returns:

Name	Type	Description
`Decimal`	`Decimal`	One person's share, rounded to two decimal places.

Raises:

Type	Description
`EasyMoneyError`	If `people` is less than 1 or `total` is not a number.

Example

The Py_simple WayThe Traditional Way

from py_simple import split_bill

share = split_bill(48, 3)

from decimal import Decimal, ROUND_HALF_UP

share = (Decimal("48") / 3).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)

`split_bill_exact(total, people)`

Splits a bill into cent-precise shares that preserve the rounded total.

Rounds the full bill once using ROUND_HALF_UP, then gives leftover cents to the first shares. Shares differ by at most one cent. Refunds use the same allocation with negative shares; zero shares are 0.00. Existing split_bill still returns one independently rounded share.

Parameters:

Name	Type	Description	Default
`total`	`int \| float \| str \| Decimal`	Finite amount. Floats are converted through their string representation.	required
`people`	`int`	Number of shares. Must be at least 1; booleans and non-integers are not accepted.	required

Returns:

Type	Description
`list[Decimal]`	list[Decimal]: Exactly `people` shares with two decimal places. For example, 10 split three ways gives 3.34, 3.33 and 3.33.

Raises:

Type	Description
`EasyMoneyError`	If the amount/count is invalid or rounding cannot be completed in the current Decimal context.

Example

The Py_simple WayThe Traditional Way

from py_simple import split_bill_exact

shares = split_bill_exact("10.00", 3)
print(shares)  # [Decimal('3.34'), Decimal('3.33'), Decimal('3.33')]
print(sum(shares))  # 10.00

from decimal import Decimal, ROUND_HALF_UP

total, people = Decimal("10.00"), 3
rounded = total.quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
numerator, denominator = rounded.as_integer_ratio()
cents = abs(numerator) * 100 // denominator
base, remainder = divmod(cents, people)
sign = -1 if rounded < 0 else 1
shares = []
for i in range(people):
    cent_share = Decimal(sign * (base + (i < remainder)))
    parts = cent_share.as_tuple()
    shares.append(Decimal((parts.sign, parts.digits, -2)))
print(shares)  # [Decimal('3.34'), Decimal('3.33'), Decimal('3.33')]
print(sum(shares))  # 10.00