When we want a random number generator that will not repeat numbers, we can use the urn (unique random number) object.
When urn has used all the numbers in its range, it requires the message "clear" before it will output again. Sometimes it can be useful to make sure that urn always outputs.
Urn is a great way to generate random tables of data or to scramble existing ones. This simple patch uses urn to create a simple alphabet cypher for encrypting messages.
The urn-jb abstraction by John Bischoff can be extremely useful if you want to autoclear the urn and prevent repetitions. urn-jb is included with max in ./examples/max-tricks/random_with_no_repeat/urn-jb.maxpat
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