Initially Range.at/2 and Range.random/1 were part of Enum.at/2 and Enum.random/1 respectively. They were just moved to their own functions because it made more sense to me.
These functions are fast enough IMO (as fast as I can think of). I would not get rid of Integer.random/1-2 as it's the base for all other random functions. I think it is very cumbersome to call `:rand.uniform(n + 1) - 1` every time a need a random number between 0 and n, and even more complicated if i want a random number between two integers. Please let me know how should I proceed thank you for your feedback On Fri, 24 Jun 2016 00:42:13 +0200 José Valim <jose.va...@plataformatec.com.br> wrote: > We should definitely optimize functions like at and random when we > can, so definitely +1 on this front. > > Regarding the other functions, I am still skeptical of their need. In > particular, if we implement Enum.random fast enough for ranges, it > would be enough to replace many of the other functions listed, like > Integer.random and Range.random. :) > > > > *José Valim* > www.plataformatec.com.br > Skype: jv.ptec > Founder and Director of R&D > > On Fri, Jun 24, 2016 at 12:21 AM, eksperimental > <eksperimen...@autistici.org > > wrote: > > > An answer from someone from the core team would be more than > > welcome on this proposal. > > > > In addition to the proposed funtions, this proposal also tackles an > > issue in Enum.random/1 when dealing with > > a ranges, which is really slow if the range is huge, since it > > delegates to take_random to be converted to a list to later pick > > one element. > > > > It optimized Enum.at/2 when dealing with ranges. > > > > Thank you. > > > > On Sat, 4 Jun 2016 08:37:19 +0700 > > eksperimental <eksperimen...@autistici.org> wrote: > > > > > I forgot to mention that Range.at/3 has been implemented. > > > > > > *************** > > > ### Range.at/3 > > > > > > It works the same way as Enum.at/3, but given a range, it returns > > > an integer at the given `index`. > > > > > > This function is used to optimize `Enum.at/3` when dealing with > > > ranges. *************** > > > > > > On Sat, 4 Jun 2016 08:18:21 +0700 > > > eksperimental <eksperimen...@autistici.org> wrote: > > > > > > > You can read this proposal formated > > > > https://github.com/eksperimental/experimental/blob/random/PROPOSAL.md > > > > > > > > # Introducing random related functions > > > > > > > > First I would like to address the need for implementing in > > > > Elixir our function for generating random integers: > > > > `Integer.random/1` All functions using random numbers, are > > > > calling `:erlang.random_uniform/1`. This Erlang function is not > > > > zero based, so there is an overhead to deal with it every time, > > > > adding and subtracting (`:rand.uniform(n + 1) - 1`), thus > > > > leading to potential bugs. > > > > > > > > > > > > ## Integer module > > > > > > > > So my proposal is to add `Integer.random/1` and > > > > `Integer.random/2` > > > > > > > > - `Integer.random(limit)` - It returns a random integer from 0 > > > > to limit (positive or negative integers) > > > > > > > > - `Integer.random(lower_limit, upper_limit)` - It returns a > > > > random integer withing two limits. > > > > > > > > > > > > ## Range module > > > > > > > > - `Range.random(range)` - It returns an integer within range. > > > > - `Range.random(range, count)` - It returns an list of `count` > > > > integers within range. count can be bigger than the range size. > > > > > > > > Uses cases: `Range.random/2` can be useful for generating > > > > charlists of random chars within a range. It is also used by > > > > `Enum.random/2` when the enumerable is a range. > > > > > > > > ## Enum module > > > > > > > > - `Enum.random(enumerable, count)` - It returns a list of count > > > > size, of random items from enumerable. The main difference with > > > > `Enum.take_random/2` is that latter will not include repeated > > > > results, and if count is greater than the number of elements > > > > in the enumerable, it will return short. So `Enum.random/2` > > > > guarantees the count of items, and allows them to be repeated. > > > > > > > > `Enum.random/1` has been updated to not to call > > > > `Enum.take_random/2`, but to use `Enum.at/3` instead. > > > > > > > > `Enum.at/3` has been optimized to use `Range.at/3` when the > > > > enumerable is a range. > > > > > > > > > > > > ## Additional functions implemented > > > > > > > > ### Integer.pad_random/2 > > > > > > > > If we are about to generate huge numbers, > > > > `:erlang.random_uniform/1` will work to a certain limit. > > > > `Integer.pad_random/2` has fine tuning options such as: > > > > - force_size: true | false > > > > - return: :integer | :positive | :negative | :zero_or_positive > > > > | :zero_or_negative > > > > > > > > This list can generate incredible HUGE integers, in a very > > > > efficient way. > > > > > > > > Use cases: benchmarking functions with different integers and > > > > data size of specific length. > > > > > > > > ### Kernel.delta/2 and Range.delta/1 > > > > > > > > I took the chance and introduce new functions that helped me > > > > archive random related functions listed above. > > > > > > > > - `Kernel.delta(number1, number2)`: It returns the absolute > > > > difference between two numbers (integer or float). > > > > - `Range.delta(range)`: It returns the absolute difference > > > > between the range limits. > > > > > > > > It may sound simple, but I had made mistakes in the past > > > > implementing a quick delta functions. > > > > > > > > > > > > ## Implemented code > > > > > > > > It can be found here: > > > > https://github.com/eksperimental/experimental/tree/random > > > > > > > > It can be cloned locally by running: > > > > > > > > $ git clone -b random --single-branch > > > > https://github.com/eksperimental/experimental.git > > > > > > > > Looking forward to hearing your opinion, > > > > > > > > — Eksperimental > > > > > > > > > > > -- > > You received this message because you are subscribed to the Google > > Groups "elixir-lang-core" group. > > To unsubscribe from this group and stop receiving emails from it, > > send an email to elixir-lang-core+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/elixir-lang-core/20160624052120.33c80adc.eksperimental%40autistici.org > > . > > For more options, visit https://groups.google.com/d/optout. > > > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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