Python Concepts

If expressions (not if statements) - "inline ifs"

Different to if statements (main difference is the use of a colon, ’:’). This syntax always requires an else statement. Similar to conditional (ternary) operators. Syntax: <value_if_true> if <condition> else <value_if_false>

n = -5
res = "Positive" if n > 0 else "Negative" if m < 0 else "Zero"
 
# The above expression can be written as
res = "Positive" if n > 0 else ("Negative" if n < 0 else "Zero")

Lambda functions

Anonymous functions (function without a name). It would be named if it is assigned. Useful for reducing complexity and repetition.

Syntax: lambda <arguments>: <expression>

# check if number is positive, negative or zero
classify = lambda num: "Positive" if num > 0 else "Negative" if num < 0 else "Zero"
 
classify(5) # Positive
classify(-5) # Negative
classify(0) # Zero
 
# multiple parameters
calc = lambda x, y: (x + y, x * y)
calc(3, 4) # (7, 12)
 
# callbacks
n = [1, 2, 3, 4, 5, 6]
list(filter(lambda x: x % 2 == 0, n)) # [2, 4, 6]
list(map(lambda x: x * 2, n)) # [2, 4, 6, 8, 10, 12]