Bad Drop Chances

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Bad Drop Chances

Postby linspatz » 07 Dec 2017, 18:49

Almost ever monster has drop chances that are flat out incorrect. http://l2rdatabase.com/us/npc/30306/ is a good example of a monster with many pieces of armor and weapons set at a drop rate of 325%, the jewelry is also obviously wrong.
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Re: Bad Drop Chances

Postby linspatz » 08 Dec 2017, 19:36

Yesterday I went and killed 3000 Maille Lizardman Pursuer on the nose and got the following.

  • 31,959 Adena
  • 7 B grade weapons
  • 19 C grade weapons
  • 39 B grade armor
  • 44 C grade armor
  • 2 A grade level 75 quest scrolls
  • 5 B grade level 75 quest scrolls
  • 51 C grade level 75 quest scrolls
  • 4 purple herbs
  • 4 yellow herbs
  • 5 blue herbs
  • 4 red herbs
  • 1 scroll: enhance weapon
  • 1 scroll: enhance accessory
  • 1 armor upgrade stone
  • 167 rune fragments (in drops of 2-5)
  • 8 dion - rare monster summoning stone - fragment

From this you should be able to do a pretty good job of figuring out why you are getting the wrong percentages from your raw data. If not, send me the raw data for this monster and I'll give it a go.
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Re: Bad Drop Chances

Postby Kiriak » 09 Dec 2017, 13:50

Thanks for the report, linspatz.
Actually the drop related data in the game is a bit messed up. There could be several groups of drop assigned to each monster, each group having it's own chance of being dropped. And then each item in the group has it's own chance of being dropped. Quite often these chances are shown above 100%. I don't know how exactly the game handles such cases, so i've tried to group the items into one list to simplify things. I've fixed the error, now the data should be closer to the game.
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Re: Bad Drop Chances

Postby linspatz » 09 Dec 2017, 16:39

I think you are right, the percentages you have are the chance for an item to drop within a subgroup and not for the subgroups chance to drop that item.

For example if you look at quest scrolls as a subgroup the data I have seems to fit. Instead of having percentages treat the numbers as whole numbers. C-grade is 203, B grade 23, A grade 7 and S grade 1. Adding them all together gets 234. Dividing the whole number by the parts gets the percentages, ie, C grade is 86.75% chance to drop when it is a scrolls turn.

Now if you look at my data I had 51 C-grade, 5 b-grade and 2 A grade scrolls drop for a total of 58. If you take 58 times each of those percentages you get that I should have recieved 50.32 C-grade, 5.7 B-grade and 1.74 A-grade scrolls. It could be a coincidence but I think that must be how it fits.

This also works with my data if you group all the items in the 400,000 to 500,000 ID range as one group.

Equipment is rather tricky though. As far as I can tell for equipment it my be grouped by armor, weapon, accessory and then by grade. Maille Lizardman Pursuer have the same percentage for all B-grade and C-grade weapons and armor but the drops greatly varied. The variation is not made up by the fact that their are 24 armor of each grade and only 18 weapons for each grade. This is why I think they are in different subgroups.

Just my thoughts.
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Re: Bad Drop Chances

Postby Kiriak » 10 Dec 2017, 09:11

Maybe it would be better to actually show each subgroup with it's chance as a different tab and then show the chance for each item inside the tab. However, i'm still not sure how to handle those over 100% values.
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Re: Bad Drop Chances

Postby linspatz » 11 Dec 2017, 02:31

The itemdrop.csv has the item groups in it. I can not for the life of me find where you have come up with the actual drop values though. Its a mystery to me.
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