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114 lines
2.6 KiB
Python
114 lines
2.6 KiB
Python
import math
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from timeit import timeit
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def num_digits(n: int) -> int:
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"""
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Find the number of digits in a number.
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>>> num_digits(12345)
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5
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>>> num_digits(123)
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3
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>>> num_digits(0)
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1
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>>> num_digits(-1)
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1
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>>> num_digits(-123456)
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6
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>>> num_digits('123') # Raises a TypeError for non-integer input
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Traceback (most recent call last):
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...
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TypeError: Input must be an integer
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"""
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if not isinstance(n, int):
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raise TypeError("Input must be an integer")
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digits = 0
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n = abs(n)
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while True:
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n = n // 10
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digits += 1
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if n == 0:
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break
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return digits
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def num_digits_fast(n: int) -> int:
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"""
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Find the number of digits in a number.
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abs() is used as logarithm for negative numbers is not defined.
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>>> num_digits_fast(12345)
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5
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>>> num_digits_fast(123)
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3
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>>> num_digits_fast(0)
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1
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>>> num_digits_fast(-1)
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1
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>>> num_digits_fast(-123456)
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6
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>>> num_digits('123') # Raises a TypeError for non-integer input
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Traceback (most recent call last):
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...
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TypeError: Input must be an integer
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"""
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if not isinstance(n, int):
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raise TypeError("Input must be an integer")
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return 1 if n == 0 else math.floor(math.log(abs(n), 10) + 1)
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def num_digits_faster(n: int) -> int:
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"""
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Find the number of digits in a number.
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abs() is used for negative numbers
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>>> num_digits_faster(12345)
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5
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>>> num_digits_faster(123)
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3
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>>> num_digits_faster(0)
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1
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>>> num_digits_faster(-1)
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1
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>>> num_digits_faster(-123456)
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6
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>>> num_digits('123') # Raises a TypeError for non-integer input
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Traceback (most recent call last):
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...
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TypeError: Input must be an integer
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"""
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if not isinstance(n, int):
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raise TypeError("Input must be an integer")
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return len(str(abs(n)))
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def benchmark() -> None:
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"""
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Benchmark multiple functions, with three different length int values.
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"""
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from collections.abc import Callable
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def benchmark_a_function(func: Callable, value: int) -> None:
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call = f"{func.__name__}({value})"
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timing = timeit(f"__main__.{call}", setup="import __main__")
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print(f"{call}: {func(value)} -- {timing} seconds")
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for value in (262144, 1125899906842624, 1267650600228229401496703205376):
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for func in (num_digits, num_digits_fast, num_digits_faster):
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benchmark_a_function(func, value)
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print()
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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benchmark()
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