Shop Spawn - Revision history

KittenAqua: /* External Links */

2023-05-24T23:48:55Z

‎External Links

KittenAqua: /* External Links */

2023-05-24T23:48:05Z

‎External Links

KittenAqua: /* External Links */

2023-05-24T23:47:21Z

‎External Links

Tinker: /* The Item Lists */

2016-01-08T19:47:27Z

‎The Item Lists

Tinker: /* D.E.R.P. relevance */

2016-01-08T15:40:29Z

‎D.E.R.P. relevance

Tinker: /* D.E.R.P. relevance */

2016-01-07T20:15:23Z

‎D.E.R.P. relevance

Tinker: re-wrote parts to improve usefulness

2016-01-02T19:27:06Z

re-wrote parts to improve usefulness

Phoil: Clarify interval

2015-12-09T08:57:49Z

Clarify interval

Tinker: Created page with "{{stub}} This page elaborates the algorithm used to populate the Items shops. It can get a bit mathsy, though understanding the algorithm can help also to understand the..."

2015-12-06T19:28:28Z

Created page with "{{stub}} This page elaborates the algorithm used to populate the Items shops. It can get a bit mathsy, though understanding the algorithm can help also to understand the..."

New page

{{stub}}

This page elaborates the algorithm used to populate the [[Items]] shops. It can get a bit mathsy, though understanding the algorithm can help also to understand the odds of finding certain items; also, should it be needed, it can help with improving the odds of finding certain items. For new players, this page is probably a bit too much.

The shop algorithm in a nutshell is:

1. Start with a list of all potential items. 
2. If quest or elite preparations are chosen, then move those items to the front of the list. 
3. Remove prepared inventory items from the list. 
4. Let the length of the list now be n. 
5. Generate a random number in the range 0 to n^2. 
6. Take the square root of that number, round down, and subtract from n-1.This is the index of the chosen item. 
7. Remove the chosen item from the list. 
8. Repeat steps 4-7 for each additional shop. 

For normal dungeon runs, the potential item list is created by adding basic items, then unlocked quest items, then elite items.

For the DERPs, the potential item list is a fixed list containing all items, but the basic items are still at the start, and elite items at the end. For a given DERP seed and a given length n, the generated random numbers will be identical, but the chosen items depend on the order of the list as affected by preparations. If both quest and elite preparations are chosen, then whichever was last in the available preparations will be at the front of the list.

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 === External Links ===
-[http://jsfiddle.net/Phoil/h9g0d7ka/] is a handy tool to calculate individual item probabilities for virtually any scenario.
+[http://jsfiddle.net/Phoil/h9g0d7ka/] is a handy tool to calculate individual item probabilities for virtually any scenario. <br>
 [https://jsfiddle.net/d59a2gqt/30/] is a modified version of the above that extends to modded items.
 {{MainNav}}

@@ Line 78: / Line 78: @@
 === External Links ===
 [http://jsfiddle.net/Phoil/h9g0d7ka/] is a handy tool to calculate individual item probabilities for virtually any scenario.
 [https://jsfiddle.net/d59a2gqt/30/] is a modified version of the above that extends to modded items.
 {{MainNav}}

← Older revision		Revision as of 23:47, 24 May 2023
Line 79:		Line 79:

	[http://jsfiddle.net/Phoil/h9g0d7ka/] is a handy tool to calculate individual item probabilities for virtually any scenario.		[http://jsfiddle.net/Phoil/h9g0d7ka/] is a handy tool to calculate individual item probabilities for virtually any scenario.
		+	[https://jsfiddle.net/d59a2gqt/30/] is a modified version of the above that extends to modded items.

	{{MainNav}}		{{MainNav}}

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 == The Item Lists ==
-Each of the three item lists follow a specific sequence. So for example, the 8 basic items have an intrinsic ranking that gives their relative position within the "Basic Items" list; this intrinsic ranking never changes. So if the {{i|Health Pendant}} is always the first item on the Basic Items list, it will remain so even if the list itself is moved down due to Quest Items / Elite Items preparations. Consequently, if no items are vetoed (or in a DERP), the Health Pendant will be the 1st, 9th, 23rd or 31st item in the list (depending on whether neither Quest Items or Elite Items are prepped; only Elite Items is prepped; only Quest Items is prepped; or both Elite and Quest items are prepped).
+Each of the three item lists follow a specific sequence. So for example, the 8 basic items have an intrinsic ranking that gives their relative position within the "Basic Items" list; this intrinsic ranking never changes. So if the {{i|Pendant of Health}} is always the first item on the Basic Items list, it will remain so even if the list itself is moved down due to Quest Items / Elite Items preparations. Consequently, if no items are vetoed (or in a DERP), the Health Pendant will be the 1st, 9th, 23rd or 31st item in the list (depending on whether neither Quest Items or Elite Items are prepped; only Elite Items is prepped; only Quest Items is prepped; or both Elite and Quest items are prepped).
 The below chart shows the five possible itemlists (depending on which item group preparations are taken):

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 * If you prepare *fewer* shop items, some items may "slide up" (i.e. give you the previous item in the list instead).<br>
 * If you prepare *more* shop items, some items may "slide down" (i.e. give you the next item in the list instead).<br>
-* Any items that would be picked by an index, but are brought in as a preparation instead, will instead give the previous item (the one with one lower index). {verification needed}
+* On top of potentially changing the indexes as mentioned above... Any prepared shop items will reduce all lower indexes by one. This is because the item is pulled from the item list before the indexes are applied to it, and since the item indexes count backwards (i.e. from the end of the item list), the same count will yield one lower index.
 == Vetoing Items ==

@@ Line 40: / Line 40: @@
 In light of the above explanations on how the item lists are populated, it is therefor possible to predict the impact of some preparations on the available items. Some rules of thumb:<br>
 * If you prepare the same *number* of shop items, you can predict with certainty how Quest/Elite Items impact the shop items, because then the item indexes are the same, only modified by the item group preparations, and the rank of the items prepared (which are removed from the list before generating the shop items).<br>
-* If you prepare *fewer* shop items, some items may "slide down" (i.e. give you the next item in the list instead).<br>
+* If you prepare *fewer* shop items, some items may "slide up" (i.e. give you the previous item in the list instead).<br>
-* If you prepare *more* shop items, some items may "slide up" (i.e. give you the previous item in the list instead).<br>
+* If you prepare *more* shop items, some items may "slide down" (i.e. give you the next item in the list instead).<br>
 == Vetoing Items ==

@@ Line 1: / Line 1: @@
 {{stub}}
-This page elaborates the algorithm used to populate the [[Items]] shops. It can get a bit mathsy, though understanding the algorithm can help also to understand the odds of finding certain items; also, should it be needed, it can help with improving the odds of finding certain items. For new players, this page is probably a bit too much.
+This page elaborates the algorithm used to populate the [[Items|Item]] shops. It can get a bit mathsy, though understanding the algorithm can help also to understand (and possibly improve) the odds of finding certain items. Also, for the [[D.E.R.P.]] challenges there is an additional consideration: given the uniform daily seed given to all players, the item spoilers sometimes posted on the [http://www.qcfdesign.com/forum/viewforum.php?f=3|"qcfdesign forums"] can be used to predict how certain preparations will impact the shops' item pools. For new players, this page is probably a bit too much.
 The shop algorithm in a nutshell is:
@@ Line 16: / Line 18: @@
 For normal dungeon runs, the potential item list is created by adding basic items, then unlocked quest items, then elite items.
-For the DERPs, the potential item list is a fixed list containing all items, but the basic items are still at the start, and elite items at the end. For a given DERP seed and a given length n, the generated random numbers will be identical, but the chosen items depend on the order of the list as affected by preparations. If both quest and elite preparations are chosen, then whichever was last in the available preparations will be at the front of the list.
+For the DERPs, the potential item list contains all items (as would be the case for a kingdom which has unlocked every item, and does not veto any), and follows the same logic as non-Daily runs, i.e. basic items are still at the start, and elite items at the end. For a given DERP seed and a given length n, the generated random numbers will be identical, but the chosen items depend on the order of the list as affected by preparations, as well as any shop items picked for any preparations. If both quest and elite preparations are chosen, then whichever was last in the available preparations will be at the front of the list.
 {{MainNav}}

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 . Remove prepared inventory items from the list. <br>
 . Let the length of the list now be n. <br>
-. Generate a random number in the range 0 to n^2. <br>
+. Generate a random number in the interval [0, n^2). <br>
 . Take the square root of that number, round down, and subtract from n-1.This is the index of the chosen item. <br>
 . Remove the chosen item from the list. <br>