Reference · Statistics

stats.harmonic_mean

stats.harmonic_mean(list) -> float

What it does

The harmonic mean of a list of numbers that are zero or more: the count divided by the sum of the reciprocals, as Python's statistics.harmonic_mean. It is the mean for rates: a trip at 40 km/h one way and 60 km/h back averages 48 km/h, not 50.

Examples

print(stats.harmonic_mean([40, 60]))print(stats.harmonic_mean([60, 60]))print(stats.harmonic_mean([2.5, 3, 10]))

48.060.03.5999999999999996

Edge cases

• A zero anywhere makes the answer 0.0, as in Python.
• One number gives that number, as a float.
• Ints and floats can mix; the answer is always a float.

print(stats.harmonic_mean([1, 0, 3]), stats.harmonic_mean([7]))

0.0 7.0

Errors

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

print(stats.harmonic_mean([1, -2]))

line 1: `stats.harmonic_mean` does not support negative values

print(stats.harmonic_mean([]))

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

Chaining

let speeds = [40, 60, 80]print(speeds | stats.harmonic_mean | round(2))

55.38

See also

stats.mean, stats.geometric_mean, stats.fmean

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