Multi-args Averaging

三参数求平均

≈ 20 min · python-functions · Open in WolfCode

Two functions. One calls the other. Smallest example of composition (Think Python §3.4) — and the DRY principle (§3.11).

The two functions

Python · runnable

def sum_three(a, b, c):
    return a + b + c

def average_three(a, b, c):
    return sum_three(a, b, c) / 3   # COMPOSITION — reuse, don't duplicate

print(sum_three(1, 2, 3))      # 6
print(average_three(1, 2, 3))  # 2.0
print(average_three(10, 20, 30))  # 20.0

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Why composition matters

From Think Python §3.11: "Functions can make a program smaller by eliminating repetitive code. Later, if you make a change, you only have to make it in one place."

Float vs int

Python · runnable

# / is true division — always returns float
print(6 / 3, type(6 / 3))    # 2.0 <class 'float'>
# // is floor division — returns int when both operands are int
print(6 // 3, type(6 // 3))  # 2 <class 'int'>

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