Reference · Vectors

vec.sub

vec.sub(list | num, list | num) -> any

What it does

Subtracts item by item: two lists of the same length give a list of their pairwise differences, a list and a number give the list with the number taken from each item, and a number and a list give the number less each item. Ints stay ints, floats stay floats, as with the - operator. Two numbers give their difference.

Examples

print(vec.sub([10, 20, 30], [1, 2, 3]))print(vec.sub([10, 20, 30], 5))print(vec.sub(100, [10, 20, 30]))print(vec.sub([1, 2], [0.5, 0.5]))

[9, 18, 27][5, 15, 25][90, 80, 70][0.5, 1.5]

Edge cases

• Order matters: vec.sub(a, b) is a - b item by item, so vec.sub(5, [1, 2]) is [4, 3], not [-4, -3].
• The empty list gives the empty list.
• Taking the mean from each item centres a list; the result is floats when the mean is.

print(vec.sub(5, [1, 2]), vec.sub([1, 2], 5))print(vec.sub([], 1))let sales = [3, 5, 4, 6, 8]print(vec.sub(sales, stats.mean(sales)))

[4, 3] [-4, -3][][-2.2, -0.20000000000000018, -1.2000000000000002, 0.7999999999999998, 2.8]

Errors

Lists of different lengths, an item that is not an int or a float, or an argument that is neither a list nor a number are runtime errors, not error values. An int result past 64 bits is an integer overflow runtime error.

print(vec.sub([1, 2], [1, 2, 3]))

line 1: `vec.sub` needs lists of the same length (2 and 3)

print(vec.sub([1, "2"], 1))

line 1: `vec.sub` expects numbers, got str and int

Chaining

The left side is what is subtracted from: xs | vec.sub(1) takes 1 from each item.

let sales = [3, 5, 4, 6, 8]print(sales | vec.sub(stats.mean(sales)) | vec.round(2))print(vec.norm(vec.sub([1, 1], [4, 5])))

[-2.2, -0.2, -1.2, 0.8, 2.8]5.0

See also

vec.add, vec.diff, vec.abs, stats.zscore, math.dist

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