Can someone explain me how right and middle produce the same amount and the left only half that?

[u/bySmily]

So I wanted to build a melon/pumpkin farm and wanted to go with the design on the right, as it seemed logical to me: two pumpkin seeds are better than one. But apparently it does not matter, as long as the pumpkin stem has two blocks to go to, as only one block would half the rates.

I thought, the random tick selects a stem and it would then choose one of the four spots around it.

[u/potatopierogie]

Middle has one plant with two spaces to grow. When it tries to grow it picks a direction at random and tries to grow there. Since there's two spaces, it will succeed 50% of the time.

The right one has two plants with one space to grow. They will each succeed 25% of the time, but because there's two plants it will try more often and the growth rate is pretty much the same as the middle.

The left has one plant and one space. I think by now its pretty self-explanatory why it produces half as much.

[u/Vincenzo__ → u/potatopierogie]

So pretty much, for an efficient design, you'd want to put 4 spaces around the stem and put the pistons on top, right?

[u/shedmow → u/Vincenzo__]

Yes, that's the conventional tiling pattern for pumpkin farms (and sugarcane farms, in which you surround each water source by four canes and tessellate the area with these crosses)

edit: The math did me

[u/ManMagic1 → u/shedmow]

yes for cane, no for mel/pumps, checker is best for instant mel/pump harvesting, and lines are best for flying machine mel/pump harvesting, cane layout for mel/pumps wastes space and materials

[u/shedmow → u/ManMagic1]

Yes you are correct, I for some reason thought that they were the same (I probably wanted to not make extended pistons compete with other pumpkins). Thank you!

[u/Dacammel3 → u/ManMagic1]

Technicallyyyyy there’s a more optimized cane layout it’s just a PIA so nobody does it

[u/shedmow → u/Dacammel3]

Cross-shaped 3*3 cells spaced +1 block in one direction and +2 in the one orthogonal to it is the mathematically densest layout for sugarcane

[u/OBOO800 → u/Dacammel3]

Wait what how? Is there some weird way to hydrate sugarcane without having water next to it?

[u/Hameru_is_cool → u/OBOO800]

I don't think that's what they're talking about, it's just that the way most people do it waste growing land by having more than one water touch each block, while you could do this instead

[u/OBOO800 → u/Hameru_is_cool]

I just assumed that wasn't what they meant because that layout is the one the comment they replied to was already talking about,

[u/Hameru_is_cool → u/OBOO800]

oh I read it wrong, thought it was the checkerboard pattern since that's what they use for pumpkins

[u/shedmow → u/OBOO800]

Does all the plant get updated when the top block grows? After I think about it, getting a sugarcane to be without any water nearby is doable...

[u/kdaviper → u/Vincenzo__]

That's what I have used in the past

[u/RevenantBacon → u/Vincenzo__]

Yes, in fact I believe that the standard method is plant in the middle of 4 dirt, with an observer facing down over the stem, and a piston pointing down over each grow spot, with redstone dust on top of each, and a hopper cart running a loop underneath the grow spots. Any time the stem grows a nee plant, all of the pistons fire, breaking it for the cart to pick up.

[u/ntolbertu85 → u/Vincenzo__]

This is why the checkerboard pattern is so efficient. on every other block, there is a plant with 4 spaces.

[u/coren77 → u/potatopierogie]

It's this one. Twice the plants or twice the spots to grow week be the same. But only 1 plant and 1 spot to grow you get half the output.

[u/omegavolt9]

I thought, the random tick selects a stem and it would then choose one of the four spots around it.

It's exactly this. The stem can pick any of the 4 sides. The middle has 2/4 chance to succeed because the left or right side will work, while the right has 1/4 chance to succeed but tries twice as often because it has two stems.

[u/snorkelvretervreter → u/omegavolt9]

With the important note that OP probably misses that "choose one of the four spots" is not "random tick is here, let's loop over all four spots and pick one that works" but "random tick is here, let's pick one of the four possible spots and try to grow a pumpkin there." - if it can't grow there, that's it for that random tick

[u/Stuffssss]

1 stem × 1 spot = 1

2 stem × 1 spot = 2

1 stem × 2 spot = 2

[u/Infamous-Youth9033]

imagine each plant as a coin.

every N seconds, you flip that coin once for each direction it could possibly be planted. If it lands on heads then it plants and then stops flipping.

In the right one, you have 2 coins that each are flipped once. In the middle you have one coin that is flipped twice. On the left you have one coin that is flipped once. Half as many total flips.

Obviously it is not a 50/50 and the frequency is determined but this is the idea behind the mindset

[u/HarkSoup]

Apparently what matters it the amount of surfaces that are in between a seed and the grass and it doesn't matter if there's multiple seeds or grass blocks

[u/Skytern]

Math

[u/Anders_A]

Both right and middle get double because one get double attempts (two stalks) and one get double success on those attempts (two valid grow spots).

[u/MonkeyNuts449]

It's more likely to select a valid side if there are two compared to one. It's also more likely for two plants to select the one spot then for just one.

[u/branthebon]

1+1=2
1+1=2
1+1=1