Reference · Statistics

stats.histogram

stats.histogram(list | null, int | list=) -> map

What it does

Counts a list of numbers into bins, as numpy's histogram: a map { counts, edges } where edges has one more float than counts has ints. With an int (10 by default) the bins are that many, equal in width, from the smallest value to the largest. With a list the bins are between the edges given, which must rise. Each bin takes the values from its left edge up to but not including its right one; the last bin includes its right edge too.

Examples

print(stats.histogram([1, 2, 2, 3, 3, 3, 4], 3))print(stats.histogram([1, 2, 2, 3, 3, 3, 4], [0, 2, 4]))let h = stats.histogram([72, 85, 90, 66, 85, 78], 3)print(h.counts, h.edges)

{ counts: [1, 2, 4], edges: [1.0, 2.0, 3.0, 4.0] }{ counts: [1, 6], edges: [0.0, 2.0, 4.0] }[2, 1, 3] [66.0, 74.0, 82.0, 90.0]

Edge cases

• A value on an inner edge goes to the bin on its right; the largest value goes to the last bin.
• Values outside the edges given are left out of every count.
• All values the same: the one range is widened by 0.5 on each side.
• No data gives zero counts over 0 to 1, not an error.
• Two edges may be the same: that bin counts nothing.
• Bins can be 1 to 1,000,000.

print(stats.histogram([1, 2, 3], [1, 2, 3]).counts)print(stats.histogram([-1, 11, 10], [0, 5, 10]).counts)print(stats.histogram([5, 5, 5], 2), stats.histogram([], 2))print(stats.histogram([1, 10], [0, 5, 5, 10]).counts, stats.histogram([1, 2, 3, 4], 1))

[1, 2][0, 1]{ counts: [0, 3], edges: [4.5, 5.0, 5.5] } { counts: [0, 0], edges: [0.0, 0.5, 1.0] }[1, 0, 1] { counts: [4], edges: [1.0, 4.0] }

Errors

A bin count outside 1 to 1,000,000, fewer than two edges, edges that fall, or an item that is not a number are each a runtime error, not an error value.

print(stats.histogram([1, 2], 0))

line 1: `stats.histogram`: bins must be from 1 to 1000000, got 0

print(stats.histogram([1, 2], [2, 1]))

line 1: `stats.histogram`: edges must be at least two, increasing

print(stats.histogram([1, "2"], 2))

line 1: `stats.histogram` expects a list of numbers, but item 1 is str

Chaining

In a pipeline the data comes first and the bins are the argument:

let ages = [23, 35, 41, 29, 52, 38, 44, 60, 31, 27]print(ages | stats.histogram(4) | get("counts"))print(ages | stats.histogram([20, 30, 40, 50, 60, 70]) | get("counts"))

[4, 3, 1, 2][3, 3, 2, 1, 1]

See also

stats.describe, stats.quantiles, count, group_by

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