Random Module

This XQuery Module contains functions for computing random values. All functions except for random:seeded-double and random:seeded-integer are non-deterministic, i. e., they return different values for each call.

Conventions

All functions and errors in this module are assigned to the http://basex.org/modules/random namespace, which is statically bound to the random prefix.

Functions

random:double

Signature	random:double() as xs:double
Summary	Returns a double value between 0.0 (inclusive) and 1.0 (exclusive).

random:integer

Signature	random:integer( $max as xs:integer := () ) as xs:integer
Summary	Returns an integer value, either in the whole integer range or between 0 (inclusive) and the given maximum (exclusive)
Errors	bounds: the maximum value is out of bounds.

random:seeded-double

Signature	random:seeded-double( $seed as xs:integer $num as xs:integer ) as xs:double*
Summary	Returns a sequence with $num double values between 0.0 (inclusive) and 1.0 (exclusive). The random values are created using the initial seed given in $seed.

random:seeded-integer

Signature	random:seeded-integer( $seed as xs:integer $num as xs:integer $max as xs:integer := () ) as xs:integer*
Summary	Returns a sequence with $num integer values, either in the whole integer range or between 0 (inclusive) and the given maximum (exclusive). The random values are created using the initial seed given in $seed.
Errors	bounds: the maximum value is out of bounds. negative: the number of values to be returned is negative.

random:gaussian

Signature	random:gaussian( $num as xs:integer ) as xs:double*
Summary	Returns a sequence with $num double values. The random values are Gaussian (i.e. normally) distributed with the mean 0.0. and the derivation 1.0.

random:seeded-permutation

Signature	random:seeded-permutation( $seed as xs:integer $items as item()* ) as item()*
Summary	Returns a random permutation of the specified $items. The random order is created using the initial seed given in $seed.

random:uuid

Signature	random:uuid() as xs:string
Summary	Creates a random universally unique identifier (UUID), represented as 128-bit value.
Examples	random:uuid() eq random:uuid() will (most probably) return the boolean value false.

Errors

Code	Description
bounds	The specified maximum value is out of bounds.
negative	The specified number of values to be returned is negative.

Changelog

Version 9.0

• Updated: error codes updated; errors now use the module namespace

Version 8.5

• Added: random:seeded-permutation

Version 8.0

• Updated: random:integer, random:seeded-integer raise error for invalid input.

The module was introduced with Version 7.5. It includes some functionality which was previously located in the Math Module.