# Predictability Of Minecraft Seeds

In a nutshell, is there anyway to predict what kind of landscape a certain seed will generate?

I've done some research and seems like the answer is no, but is there some sort of general guideline, like seeds with just letters results in largely desert landscapes or that negative numbers as seeds result in large tundra biomes.

Thank You!

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I'm not a minecraft player; I just wanted to comment that if this seed is used as its name suggests - as a seed for a pseudo-random-number-generator - then the answer will be "no", you cannot find any predictable relation between seed value and generated terrain. – Oak Apr 26 '11 at 5:59
possible duplicate of Minecraft seeds for a high landscape? – ChrisF Apr 26 '11 at 13:21
As far as I know landscapes are generated using a highly tweaked version of 2D (maybe 3D?) Perlin noise, so if you knew the hash function that converts seeds into an internal integer and you knew exactly how Notch tweaked Perlin noise then yes, you could determine the landscape by generating it yourself. Then again, even if you knew this it's easier to generate the map and browse it in Cartographer G. – Sadly Not Apr 26 '11 at 14:13
@Oak yes, that is exactly what the seed is for, but it is a pseudo random number generator we are talking about here. And knowing the kind of people that frequent this website I just thought that it wouldn't be all that surprising if somebody would have figured out the algorithm or perhaps created some close approximation. – chandsie Apr 26 '11 at 23:05
Also, @Sadly Not if that were an answer I would accept that as the correct one. :] I just don't know how I didn't think of a map editing software to begin with... I guess I was looking for some way to have a certain type of landscape, but still have the generated world be somewhat unique and random. – chandsie Apr 26 '11 at 23:07

As Oak has said, the seed is used to seed a pseudo random number generator, which makes it (in practice) impossible to determine. However, to make things worse, the given seed is first run through a hash function ( http://en.wikipedia.org/wiki/Hash_function ) that (should) generate wildly different values with the changing of 1 letter.

In short, there is no useful correlation between the seed input ("Gargamel" for example) and the seed used (some number). And even if there was it wouldn't get you very far.

Update (for clarification):

This does not mean that using the same seed will generate a different map (else sites like minecraftseeds.info wouldn't work), the hash function will always generate the same output given the same input and the pseudo random number generator will always create the same sequence from this number. It does mean however, that changing one bit of the seed (say, "Gargamel" versus "Gbrgamel") will create a different map, which will usually have very little in common with the first map.

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Is this (minecraftseeds.info) website not based on the idea that using the same seed will provide you the same map? – chandsie Apr 26 '11 at 23:01
@chands Using the same seed twice will give you the same map each time, but the point Yourdoom is making here is that if you change one character in the seed, it will produce a completely different map. – Jason Plank Apr 27 '11 at 1:00
Okay, I guess I see the point here. Thank you for your patience and great comments everyone! – chandsie Apr 27 '11 at 4:59
Should I paraphrase the comments in the answer? – Kevin van der Velden Apr 27 '11 at 8:55
Well, technically its possible that it's the same map (hash collisions and all that) but in all likelihood the differences will be far greater that the similarities, but you are right, I'll change the language a bit. – Kevin van der Velden Apr 28 '11 at 11:14

The short answer is 'No', as you already found out through your research. A common property of most (pseudo-)random generators, including the one used by Minecraft terrain generator, is that 'similar' seeds give wildly different results.

There is no way of predicting that e.g. negative numbers will produce certain features more often. As for the letters in the seed - if the seed contains them, the string is converted to a numerical seed using a certain calculation (`String.hashCode()` to be exact).

That said, there is some difference between numerical seeds and seeds with letters, but it has almost no practical implications: numerical seeds are 64 bit numbers, while seeds with letters are hashed to a 32 bit number. This means that there are 18 quintillion possible Minecraft worlds, but if you use a seed with a letter in it, you can generate 'only' 4 billion of them.

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Don't forget that you can create some other text that results in the same hashcode as a given text and will thus result in the same seed. – Arperum Jun 13 '14 at 9:53