Python/maths/series/geometric_mean.py

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"""
GEOMETRIC MEAN : https://en.wikipedia.org/wiki/Geometric_mean
"""
def is_geometric_series(series: list) -> bool:
"""
checking whether the input series is geometric series or not
>>> is_geometric_series([2, 4, 8])
True
>>> is_geometric_series([3, 6, 12, 24])
True
>>> is_geometric_series([1, 2, 3])
False
>>> is_geometric_series([0, 0, 3])
False
"""
if len(series) == 1:
return True
try:
common_ratio = series[1] / series[0]
for index in range(len(series) - 1):
if series[index + 1] / series[index] != common_ratio:
return False
except ZeroDivisionError:
return False
return True
def geometric_mean(series: list) -> float:
"""
return the geometric mean of series
>>> geometric_mean([2, 4, 8])
3.9999999999999996
>>> geometric_mean([3, 6, 12, 24])
8.48528137423857
>>> geometric_mean([4, 8, 16])
7.999999999999999
>>> geometric_mean(4)
Traceback (most recent call last):
...
ValueError: Input series is not valid, valid series - [2, 4, 8]
>>> geometric_mean([1, 2, 3])
Traceback (most recent call last):
...
ValueError: Input list is not a geometric series
>>> geometric_mean([0, 2, 3])
Traceback (most recent call last):
...
ValueError: Input list is not a geometric series
>>> geometric_mean([])
Traceback (most recent call last):
...
ValueError: Input list must be a non empty list
"""
if not isinstance(series, list):
raise ValueError("Input series is not valid, valid series - [2, 4, 8]")
if len(series) == 0:
raise ValueError("Input list must be a non empty list")
if not is_geometric_series(series):
raise ValueError("Input list is not a geometric series")
answer = 1
for value in series:
answer *= value
return pow(answer, 1 / len(series))
if __name__ == "__main__":
import doctest
doctest.testmod()