stat

The stat package computes descriptive statistics over lists of numbers.

data = [2, 4, 4, 4, 5, 5, 7, 9]

println stat::mean(data)            # 5
println stat::median(data)          # 4.5
println stat::mode(data)            # [4]
println stat::range(data)           # 7
println stat::variance(data)        # 4.571428571428571
println stat::stdev(data)           # 2.138089935299395
println stat::stdev(data, true)     # 2 (population standard deviation)
println stat::percentile(data, 90)  # 7.6

variance and stdev compute the sample statistic by default; pass true as the second argument for the population statistic. mode returns a list, since several values can tie.

Relationships and shape

x = [1, 2, 3, 4]
y = [2, 4, 5, 9]

println stat::correlation(x, y)          # Pearson correlation, from -1 to 1
println stat::covariance(x, y)
println stat::zscore([1, 2, 3])          # [-1, 0, 1]
println stat::normalize([10, 20, 30])    # [0, 0.5, 1]
println stat::frequency(["a", "b", "a"]) # {"a": 2, "b": 1}

sum, min, max and sorted round out the package. For timing statistics, see bench::stats.

Functions

stat::sum

stat::sum(data)

Computes the sum of a list of numbers.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns integer|float — The sum.

stat::min

stat::min(data)

Returns the minimum value in a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns integer|float — The minimum value.

stat::max

stat::max(data)

Returns the maximum value in a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns integer|float — The maximum value.

stat::range

stat::range(data)

Computes the range (max - min) of a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns integer|float — The range.

stat::mean

stat::mean(data)

Computes the arithmetic mean of a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns float — The mean.

stat::sorted

stat::sorted(data)

Returns a sorted copy of a list.

Parameter	Type	Default	Description
data	list		A list of comparable values.

Returns list — Sorted list.

stat::median

stat::median(data)

Computes the median of a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns integer|float — The median.

stat::mode

stat::mode(data)

Returns all modes (most frequent values) of a list.

Parameter	Type	Default	Description
data	list		A list of values.

Returns list — A list of modal values.

stat::variance

stat::variance(data, population = false)

Computes the variance of a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.
population	boolean	false	If true, computes population variance. Defaults to false (sample).

Returns float — The variance.

stat::stdev

stat::stdev(data, population = false)

Computes the standard deviation of a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.
population	boolean	false	If true, computes population stdev. Defaults to false (sample).

Returns float — The standard deviation.

stat::percentile

stat::percentile(data, p)

Computes the p-th percentile of a list (linear interpolation).

Parameter	Type	Default	Description
data	list		A list of numeric values.
p	integer|float		Percentile in [0, 100].

Returns float — The p-th percentile.

stat::covariance

stat::covariance(x_data, y_data)

Computes the sample covariance of two lists.

Parameter	Type	Default	Description
x_data	list		First list of numeric values.
y_data	list		Second list of numeric values.

Returns float — The sample covariance.

stat::correlation

stat::correlation(x_data, y_data)

Computes the Pearson correlation coefficient of two lists.

Parameter	Type	Default	Description
x_data	list		First list of numeric values.
y_data	list		Second list of numeric values.

Returns float — Correlation in [-1, 1].

stat::zscore

stat::zscore(data)

Computes z-scores (standard scores) for a list.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns list — List of z-scores.

stat::frequency

stat::frequency(data)

Computes a frequency table for a list.

Parameter	Type	Default	Description
data	list		A list of values.

Returns hashmap — Maps each unique value (as string) to its count.

stat::normalize

stat::normalize(data)

Normalizes a list to [0, 1] range.

Parameter	Type	Default	Description
data	list		A list of numeric values.

Returns list — Normalized values.