04 - Numbers and Arithmetic.md

Numbers and Arithmetic

Ints

'Ints' represent integers, or 'whole numbers', and they can be positive or negative.

x = 5
print(x)
>>> 5

Floats

'Float' is stort for 'floating-point number', which represents an approximation of a real number. Floats may also be written with an exponent, designated by e: 3.12e6 is 3,120,000.

x = 5.23
print(x)
>>> 5.23

There are also three special values floats may take: positive infinity, negative infinity, and NaN. NaN is short for 'not a number', it's the result of some mathematical operations, particularly in numpy. You can check for these values with the math module.

import math

x = float('nan')
print(math.isnan(x))

y = float('inf')
print(math.isinf(y))

z = float('-inf')
print(math.isinf(z))
print(math.isfinite(z))

The math module has many other specialized math functions you can utilize, a full list of them can be found here

Arithmetic Operators

• + addition
• - subtraction
• * multiplication
• / division
• // floor division, results in an int
• % modulus, a%b is the remainder of a/b
• ** exponentiation

Modulus is the 'remainder function' for example, 5%2 is 1, 6%2 is 0, 23%5 is 3, etc. It's also useful for containing the range of a variable.

i = 0
while i < 100:
    print(i%3)
    i = i + 1
>>> 0
>>> 1
>>> 2
>>> 0
>>> 1
>>> 2
>>> 0
etc

For each of the arithmetic operators, there are short-hand versions, which compute a result and store it as the original variable: x += 2 is equivalent to x = x + 2.

x = x + 2
x += 2

x = x - 2
x -= 2

x = x * 2
x *= 2

etc