My go-to solution for random id numbers which programmers frequently need

gistfile1.rb

# yields an 11 digit number in base-36
# with an equal probability distribution for all digits
(0..10).to_a.map {(rand*36).to_i.to_s(36)}.join

# this is slightly preferable to the more simple
(rand*(36**11)).to_i.to_s(36) 

# because any number so generated will occasionally be "short"
# and because the first digit will follow a non-random distribution
# in terms of frequency due to some strange number theory thing
# that was only proven in the last decade i think

In response to: https://twitter.com/mxlje/status/495600027880783872

Why use space-inefficent UUIDs?

This code gives me numbers like:

tg9wa3kb9ojskx80zlz9
q0j0c8xrt7vxetnekcqw

36**20 is more than enough... usually 5-10 digits is plenty. 8 digits gives you nearly 3 trillion.

Base 36 gives 5.17 bits of entropy for every digit.

Base 36 encoding is great for encoding sequential ids too and much more compact... suitable for url shorteners, etc.

Thanks, I’ll definitely keep that in mind. A nice thing about UUIDs though is that they don’t include o, i, l and some other chars which makes them a lot more readable. Of course that may not be necessary for everything, but for some use cases it’s great. Also iBeacons :)