Common Patterns

This page is intended as a list of commonly used snippets and functions that can be used in K code.

If you would like to add to this list, modify the template given in Format: Common Pattern and paste it in.

Sum

+/

Description: function to sum an array. Can be used with initial value.

Examples

+/1 2 3 4 5
+/(1 2;2 3)

ngn/k

Dialects: all

Primitives: plus, over

Deltas

-':

Description: Function to find the differences between members of an array. Comes in various flavors.

Examples:

-':1 2 3 4 /the builtin eachp prepends an array with zero before evaluation, so the output is the same size

-':5 2 4 8

{y/(1_;-1_)@\:x}[6 7 8;-] /you can substitute the default eachp with your own for different behaviour, like this shakti example that just evaluates over each pair in x without prepending 0

-':6 7 8  /the difference is highlighted here

ngn/k

Dialects: all, syntax may vary

Primitives: eachp, minus

Rotate 90 degrees left

|+:

Description: function which rotates a matrix 90 degrees left(counterclockwise).

Example

|+3 3#!9

ngn/k

Dialects: all

Primitives: transpose, reverse