Reference · Statistics

stats.geometric_mean

stats.geometric_mean(list) -> float

What it does

The geometric mean of a list of positive numbers: the n-th root of their product, computed through logarithms as Python's statistics.geometric_mean does. It is the mean to use for growth factors and ratios: the geometric mean of yearly growth factors is the steady factor that gives the same total growth.

Examples

print(stats.geometric_mean([1, 4, 16]))print(stats.geometric_mean([54, 24, 36]))print(stats.geometric_mean([1.05, 1.1, 0.95]))

4.036.0000000000000141.031419164168326

Edge cases

• The way through logarithms can leave the last digit off: one number comes back as itself up to rounding, [7] gives 6.999999999999999.
• Every number must be positive: a zero is an error, not 0.0.
• Ints and floats can mix; the answer is always a float.

print(stats.geometric_mean([7]), stats.geometric_mean([7]) | round(6))print(stats.geometric_mean([2, 8.0]))

6.999999999999999 7.04.0

Errors

No data, a zero, a negative number or something that is not a number are each a runtime error, not an error value.

print(stats.geometric_mean([1, 0, 4]))

line 1: `stats.geometric_mean` requires positive numbers

print(stats.geometric_mean([]))

line 1: `stats.geometric_mean` requires at least one data point

Chaining

let returns = [0.05, 0.10, -0.05]print(returns | map((r) => 1 + r) | stats.geometric_mean | round(4))

1.0314

See also

stats.mean, stats.harmonic_mean, math.prod

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