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Re: Generating pseudo-random integers
From: |
Pádraig Brady |
Subject: |
Re: Generating pseudo-random integers |
Date: |
Sat, 05 Feb 2011 11:42:14 +0000 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 |
On 05/02/11 07:51, Jim Meyering wrote:
> Melikamp T. Medley wrote:
>
>> Thanks!
>>
>> I think I want to write a utility that prints pseudo-random
>> integers (I have in CL, but I like it fast, so this time in C),
>> and link it with coreutils. I looked at Paul Eggert's work,
>> and I won't be able to do any better than that if I spend
>> years on it :) I want to print uniformly distributed integers
>> fast, formatted, in bulk if needed. And I want to call it roll.
>> Let me know if you have a word of advice.
>>
>> On 02/04/2011 11:35 PM, Eric Blake wrote:
>>> Using just coreutils, though, I'm afraid your options are slim. You
>>> could use 'seq 0 9 | sort -R | head -n1' (or use shuf instead of sort
>>> -R) to generate one random number at a time, but that gets expensive.
>>> Or, if you don't mind limiting yourself to 62**6 values (instead of the
>>> more traditional 2**32), you could do 'mkdir tmp; mktemp -u -p tmp
>>> XXXXXX'. But that's the extent of coreutils' randomness exposed to the
>>> user.
>
> It's hard to justify writing a new program in C
> when you can do the job with a Perl one-liner:
>
> $ perl -le 'foreach (1..20) { print int rand 1000 }'
> 423
> 619
> 917
> 396
> 957
> 345
> 892
> 13
> 424
> 519
> 898
> 689
> 208
> 383
> 605
> 196
> 384
> 893
> 618
> 344
>
> However, adding an *option* to shuf might make sense,
> since you can already give shuf both a range and a count
> of how many numbers to print.
Sorry for being dense, but what option shuf is needed? formatting?
Though on trying shuf to generate the numbers I notice:
$ shuf -i0-$((2**31)) -n1
1241475845
$ shuf -i0-$((2**31)) -n2
shuf: memory exhausted
cheers,
Pádraig.
- Generating pseudo-random integers, Melikamp T. Medley, 2011/02/04
- Re: Generating pseudo-random integers, Eric Blake, 2011/02/04
- Re: Generating pseudo-random integers, Melikamp T. Medley, 2011/02/05
- Re: Generating pseudo-random integers, Bob Proulx, 2011/02/05
- Re: Generating pseudo-random integers, Melikamp The Medley, 2011/02/05
- Re: Generating pseudo-random integers, Bob Proulx, 2011/02/05
- Message not available
- Message not available
- Re: Generating pseudo-random integers, Melikamp The Medley, 2011/02/05
- Re: Generating pseudo-random integers, Bob Proulx, 2011/02/05
- Re: Generating pseudo-random integers, Melikamp T. Medley, 2011/02/07
- Re: Generating pseudo-random integers, Jim Meyering, 2011/02/05
- Re: Generating pseudo-random integers,
Pádraig Brady <=
- Re: Generating pseudo-random integers, Jim Meyering, 2011/02/05