(25C) Sampling without repetition
10-28-2018, 09:18 AM (This post was last modified: 10-28-2018 09:20 AM by Dieter.)
Post: #3
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: (25C) Sampling without repetition
(10-27-2018 03:52 PM)Thomas Klemm Wrote:  Here's a translation of your program for the HP-42S:
Code:
... 15 DSE 03 16 GTO 01 17 GTO 02 18▸LBL 01 ...

One more case where something like INV DSZ would be useful (greetings to the TI community ;-)). This can be accomplished quite easily by having the DSE followed by a test that always tests false. Since X holds a positive number at this point, a simple x<0? will do.

Code:
... 15 DSE 03 16 X<0? 17 GTO 02 ...

Slightly shorter, slightly faster, saves one label.
Edit: OK, in this special case it's neither shorter nor label-saving, simply because LBL 01 is required anyway. #-)

(10-27-2018 03:52 PM)Thomas Klemm Wrote:
(04-27-2017 04:07 AM)nsg Wrote:  I wonder if it is possible to improve on the algorithm and generate a sample of modest k for arbitrary N, for example, a sample of 30 out of 10000000.
In this case we might simply generate them at random and hope there's no collision.

In such a case there is no significant difference between sampling with or without repetition. So it doesn't matter much if a number is drawn twice. Otherwise the idea is: record the sample in a (sorted) list, generate the next number, see if it's part of the list. If yes: get a new number, if not: insert it into the list. Hmmm... somehow this sounds like a job for the HP50. ;-)

Dieter
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 Messages In This Thread (25C) Sampling without repetition - nsg - 04-27-2017, 04:07 AM (42S) Sampling without repetition - Thomas Klemm - 10-27-2018, 03:52 PM RE: (25C) Sampling without repetition - Dieter - 10-28-2018 09:18 AM RE: (25C) Sampling without repetition - John Keith - 10-28-2018, 08:03 PM RE: (25C) Sampling without repetition - Albert Chan - 10-28-2018, 08:51 PM RE: (25C) Sampling without repetition - Albert Chan - 10-28-2018, 02:18 PM RE: (25C) Sampling without repetition - Thomas Klemm - 10-28-2018, 03:42 PM

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