Timeline for Shuffle a subsequence
Current License: CC BY-SA 4.0
38 events
| when toggle format | what | by | license | comment | |
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| Feb 19, 2023 at 20:00 | answer | added | Shaggy | timeline score: 0 | |
| Dec 30, 2021 at 0:43 | comment | added | att | In general, for a list of length \$l\$, the probability of a permutation that keeps \$d\$ points fixed should be \$\frac1{2^l-1}\sum_{i=1}^l\frac1{i!}{d \choose d-l+i}\$. | |
| Dec 29, 2021 at 21:48 | answer | added | Dominic van Essen | timeline score: 3 | |
| Dec 29, 2021 at 21:00 | history | tweeted | twitter.com/StackCodeGolf/status/1476296990778707968 | ||
| Dec 29, 2021 at 19:55 | answer | added | pajonk | timeline score: 4 | |
| Dec 29, 2021 at 16:30 | answer | added | Ajax1234 | timeline score: 1 | |
| Dec 29, 2021 at 15:40 | answer | added | ovs | timeline score: 2 | |
| Dec 29, 2021 at 15:14 | answer | added | rydwolf | timeline score: 1 | |
| Dec 29, 2021 at 14:53 | comment | added | thejonymyster | @Razetime that's what I thought too, but if you look at tsh's distributions for input [1, 2, 3] you'll note that the probabilities are not all equal, as they'd be with a standard random shuffle of the entire input. | |
| Dec 29, 2021 at 12:19 | answer | added | Dominic van Essen | timeline score: 3 | |
| Dec 29, 2021 at 12:06 | answer | added | Noodle9 | timeline score: 1 | |
| Dec 29, 2021 at 11:57 | comment | added | Razetime | so then it i s just simply a random shuffle, no? | |
| Dec 29, 2021 at 10:12 | answer | added | Graham | timeline score: 2 | |
| Dec 29, 2021 at 9:41 | comment | added | Dominic van Essen | @Razetime - I doubt it, because that approach could never regenerate the original array, which should be one of the valid ouputs. | |
| Dec 29, 2021 at 9:25 | answer | added | Jayant Choudhary | timeline score: 1 | |
| Dec 29, 2021 at 8:56 | history | became hot network question | |||
| Dec 29, 2021 at 8:29 | comment | added | Razetime | can't this be done by simply making a random shuffle not equal to the array? | |
| Dec 29, 2021 at 8:22 | answer | added | Neil | timeline score: 3 | |
| Dec 29, 2021 at 7:12 | answer | added | loopy walt | timeline score: 3 | |
| Dec 29, 2021 at 5:24 | comment | added | tsh |
To my understanding, output for [1, 2, 3] should be \$\frac{2}{3}\$ [1, 2, 3]; \$\frac{2}{21}\$ [2, 1, 3]; \$\frac{2}{21}\$ [1, 3, 2]; \$\frac{2}{21}\$ [3, 2, 1]; \$\frac{1}{42}\$ [3, 1, 2]; \$\frac{1}{42}\$ [2, 3, 1]. If I was calculated correctly... I would suggest answers show destribution of input [1, 2, 3] and confirm it meats the requirement of distribution.
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| Dec 29, 2021 at 3:59 | answer | added | Kjetil S | timeline score: 4 | |
| Dec 29, 2021 at 3:24 | history | edited | hyperneutrino♦ | CC BY-SA 4.0 |
added 2 characters in body
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| Dec 29, 2021 at 3:20 | comment | added | Jonathan Allan | @emanresuA I believe that you are thinking of "substring", see this math post. | |
| Dec 29, 2021 at 3:10 | answer | added | Jonah | timeline score: 5 | |
| Dec 29, 2021 at 2:29 | comment | added | caird coinheringaahin g♦ | @pxeger As stated at the start of the challenge, "choose randomly" in this case means that a uniform distribution should be used, and every non-empty subsequence should have the same probability of being chosen. It doesn't have to compute the powerset (but I suspect that most will) so long as each is uniformly chosen | |
| Dec 29, 2021 at 2:24 | comment | added | pxeger | I think you need to specify more exactly what "elect a randomly chosen, non-empty subsequence from the array" means, because there are multiple reasonable ways to do this with different distributions. Does it have to be equivalent to computing the input's powerset (without the empty list) and choosing one of those sets randomly? | |
| Dec 29, 2021 at 2:07 | comment | added | caird coinheringaahin g♦ | @tsh As to not invalidate the current answers, I think going by indices is a better choice | |
| Dec 29, 2021 at 2:06 | comment | added | tsh | How should I choose sub-sequence? For input [2, 3, 4, 3, 4, 5], if we choose sub-sequence by their values, say [2, 3, 4, 5], then both [2, 3, 4, 4, 3, 5], [2, 3, 3, 4, 4, 5], [2, 4, 3, 3, 4, 5] may be a valid output. But if we choose by their indexes, say [0, 1, 2, 5], then only [2, 3, 4, 4, 3, 5] in above examples are still valid. | |
| Dec 29, 2021 at 1:42 | answer | added | att | timeline score: 3 | |
| Dec 29, 2021 at 1:02 | answer | added | lyxal | timeline score: 3 | |
| Dec 29, 2021 at 1:02 | comment | added | caird coinheringaahin g♦ | @ZaMoC Yes, there may be repeats | |
| Dec 29, 2021 at 1:01 | comment | added | ZaMoC | Can the array have repeated digits? | |
| Dec 29, 2021 at 1:00 | answer | added | hyperneutrino♦ | timeline score: 6 | |
| Dec 29, 2021 at 0:59 | comment | added | caird coinheringaahin g♦ | @U12-Forward No, the subsequence can be of any length between 1 and the length of the input. "a random non-empty subsequence" refers to choosing from all non-empty subsequences of the input | |
| Dec 29, 2021 at 0:58 | comment | added | U13-Forward | Do the subsequences need to be length 3? | |
| Dec 29, 2021 at 0:57 | history | edited | caird coinheringaahin g♦ | CC BY-SA 4.0 |
added 4 characters in body
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| Dec 29, 2021 at 0:55 | comment | added | emanresu A |
subsequence implies contiguous, you might want to specify that it's all subsets
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| Dec 29, 2021 at 0:54 | history | asked | caird coinheringaahin g♦ | CC BY-SA 4.0 |