SimpleStatistics

Get the geometric mean of an enumerable.

If the enumerable is empty, Enumerable::EmptyError will be raised. If the enumerable contains negative numbers, SimpleStatistics::InvalidNumberError will be raised.

SimpleStatistics.geometric_mean([2, 8])
# => 4

Performs a simple linear regression. Returns a Line.

If only one coordinate is provided, the resulting Line will be flat (i.e., have a slope of 0).

If the enumerable is empty, Enumerable::EmptyError will be raised. If any of the coordinates don't have a size of 2, a BadCoordinateError will be raised.

line = SimpleStatistics::linear_regression([[0, 0], [1, 1]])

line.slope      # => 1
line.intercept  # => 0
line.at(2)      # => 2

Get the arithmetic mean (also known as the average) of an enumerable. This is the sum of all of the values divided by the number of values.

If the enumerable is empty, Enumerable::EmptyError will be raised.

SimpleStatistics.mean([3, 1, 2])
# => 2

SimpleStatistics.mean([9, 9])
# => 9

SimpleStatistics.mean([])
# raises Enumerable::EmptyError

Get the median of an enumerable. This is the "middle value".

If the enumerable is empty, Enumerable::EmptyError will be raised.

SimpleStatistics.median([3, 1, 2])
# => 2

SimpleStatistics.median([0, 2, 3, 5])
# => 2.5

Get the median of a sorted enumerable. If you already know that the enumerable is sorted, this is faster than using median.

If the enumerable is empty, Enumerable::EmptyError will be raised.

SimpleStatistics.median_sorted([1, 2, 3])
# => 2

SimpleStatistics.median_sorted([0, 2, 3, 5])
# => 2.5

Get the mode of an enumerable, which is the value that appears most frequently. If there is a tie, the most recently-seen mode will be returned.

If the enumerable is empty, Enumerable::EmptyError will be raised.

SimpleStatistics.mode([5, 4, 4, 3])
# => 4

SimpleStatistics.mode([5, 4.0, 4, 3])
# => 4

SimpleStatistics.mode([1, 1, 2, 2, 3])
# => 1

Get the quantile from an enumerable.

If the enumerable is empty, Enumerable::EmptyError will be raised. If the second argument is not in the range (0..1), SimpleStatistics::BadQuantileError will be raised.

SimpleStatistics.quantile([3, 1, 2], 0.5)
# => 2

SimpleStatistics.quantile([3, 1, 2], 0)
# => 1

SimpleStatistics.quantile([4, 3], 0.5)
# => 3.5

Get the quantile from a sorted enumerable. If you already know that the enumerable is sorted, this is faster than using quantile.

If the enumerable is empty, Enumerable::EmptyError will be raised. If the second argument is not in the range (0..1), SimpleStatistics::BadQuantileError will be raised.

SimpleStatistics.quantile_sorted([1, 2, 3], 0.5)
# => 2

SimpleStatistics.quantile_sorted([1, 2, 3], 0)
# => 1

SimpleStatistics.quantile_sorted([3, 4], 0.5)
# => 3.5

Get the minimum and maximum of an enumerable as a range. If the enumerable is empty, the range will be infinite and contain all values.

SimpleStatistics.range([3, 1, 2])
# => (1..3)

SimpleStatistics.range([5, 5, 5])
# => (5..5)

SimpleStatistics.range([] of Int32)
# => (..)

Get the standard deviation from an enumerable. This is the square root of the variance.

If the enumerable is empty, Enumerable::EmptyError will be raised. If the enumerable only has one entry, 0 will be returned.

SimpleStatistics.standard_deviation([2, 4, 4, 4, 5, 5, 7, 9])
# => 2

SimpleStatistics.standard_deviation([99])
# => 0

Get the variance of an enumerable.

If the enumerable is empty, Enumerable::EmptyError will be raised.

SimpleStatistics.variance((1..6))
# => 2.91666...

SimpleStatistics.variance([])
# raises Enumerable::EmptyError