Challenge #123: When will Rabbits Rule the World?

This one has been on my whiteboard for awhile and I've been meaning to publish this challenge. This weekly challenge should be a fun one! The question we are trying to answer is: In what future month/year will a new breed of rabbits to exceed the human population 2:1?

Let's set some rules for how this new breed of rabbit populates so we can try to find the day our civilization will be be under the rule of our new-found long-eared overlords.

1) We will start with 1 female and 1 male rabbit born today (0 months old)
2) Each month, each female produces a litter of 4 bunnies: 1 male and 3 females
3) A female cannot start to reproduce until she has matured to 4 months of age
4) All rabbits live only to 24 months in age. (Alive months 0-23, they cease to live at the start of the 24th month)

5) Don't forget human population grows too! Assume a 0.058% month over month human population growth!

I have provided an answer, but there may be little monthly nuances that account for slightly different answers. Sound-off on when you found out it is going to happen!

challenge_123_start_file.yxmd

challenge_123_solution.yxzp

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All comments

patrick_digan

Spoiler

I went for an iterative macro. It only took 41 iterations.
Workflow:

Macro:

challenge_123_start_file.yxzp

TerryT

I got the same month, but my numbers don't match exactly!

Spoiler

challenge_123_TTT.yxzp

CharlieS

I got the same date, but slightly different population counts for humans and the Supreme Overlords. Maybe this is close enough to count like in horseshoes and Holy Hand Grenades.

Spoiler

785,514,304 long-eared overlords and 336,183,913 humans

Challenge_0123-CharlieS_Solution.yxzp

NicoleJohnson

Slightly different human population for my final result, with 24 extra humans - which frankly, in this terrifying scenario, I will gladly take.

Spoiler

Thanks for the super fun challenge, @JoeM! I can see why you were so excited for this one Now, off to go pull anything that looks like a carrot out of my garden, just in case...

Cheers,

challenge_123_NicoleJohnson.yxzp

terry10

Averting my eyes from the GIF, I didn't notice the 2:1 population threshold and spent way too much time trying to find the error in my workflow.

Spoiler

challenge_123_terry10.yxzp

mmongeon

Here's my solution.

Like many of the other submissions, I don't have the exact same population numbers, but I end up on the same month.

Spoiler

Main workflow:
Capture 123 main.JPG

Iterative macro:
Capture 123 macro.JPG

challenge_123_mongeon_complete.yxzp

patrick_digan

@mmongeon Your solution truly made my day! 51 formulas in one formula tool!

Ladarthure

Was very funny and made me learn how to use the iterative macro, thank's to @patrick_digan for the first answer and showing a way to do this macro (was planning to use multi_rows formula...

challenge_123_start_file.yxmd

ggruccio

Going to see iterations of rabbits in my sleep!

challenge_123_gg_finish.yxzp

danrh

I hate to be Johnny Raincloud, but while I got to the provided date, I wonder if it might actually be 7 months sooner ...

Spoiler

The difference is when a rabbit starts reproducing ( > 4 months or >= 4 months). Reading through the problem, it sounds like >= 4 months ...

Please correct me if I'm wrong. I'd appreciate every extra day I can get.

Death by Bunnies.yxmc

mmongeon

@danrh

I had the same kind of problem, I had to interpret the assignment as if female rabbits start reproducing at 4 months but give birth the next month, so (> 4) and not (>= 4).

This is how I was able to get the right month, but I was still a little off on the exact population number, so there may be more to it than that.

mmongeon

Here's a second solution.

Spoiler

"Look Ma, no Iterative Macros!"
Getting creative... putting the male and female rabbit population in a single column so I can calculate and store the 2 values with a single Multi-Row Formula tool.
Capture 123 2.JPG

challenge_123_mongeon_complete_2.yxmd

Ukashi

Hi @patrick_digan

you have me puzzeled, you mentioned 41 iteration but how with that number of iteration you end up on date 2022-08-02 shouldn't that date mean something like 48 iterations (it is 4 years from starting date) , or alternatively with 41 iteration shouldn't you end around 2022-01-02?

Ukashi

Hello,

That is a fun challenge

I was struggling a bit with my results bit thanks to @danrh I got back on track becouse I was afraid that bunnycalypse will come 7 month earlier

Spoiler

challenge_123_Ukashi Solution.yxzp

patrick_digan

@Ukashi good catch. I did land on 48 iterations for my final version. The 41 iterations was when I let the bunnies reproduce a month earlier. I changed it to match the solution provided.

clant

This was a fun one. I still havent worked out how to make the macro stop so if anyone can help me with that id appreciate it!

Thanks

Chris

challenge_123_start_file.yxzp

kat

Spoiler

this took me a good while to solve! here it is with the 7 month earlier answer.

Challenge #123 final.PNG

macro:

Challenge #123.yxzp

Ruud

Spoiler

Also bit different numbers, but same month.

Bunnies	Human Pop	Date
784861560	336183889	2022-08-02

challenge_123_ruud.yxmc

ggruccio

Hi @clant,

You'll need to structure your workflow so the iteration macro output comes after the filter (i.e. only send it back thru the loop until the criteria is met). I've just given you a simple snapshot from your workflow to show how the logic should work. Given that you've summarized the data prior to the filter you may need to reconstruct the dataset downstream before sending it back through Hope this helps!

Spoiler

benjamesdavis

What version was this made in? I can't open the file with 11.0.3.

Thanks,
Ben

clant

Hi @benjamesdavis, I did this in 2018.2 sorry, i just upgraded mine the other day.

thanks

chris

jvansistine

This one expanded my horizons a bit with iterative macros!

challenge_123_solution_jvs.yxmd

jasperlch

challenge_123_JL.yxzp

Ayelavan

Great question. Wasn't an easy solution but got there eventually.

Here is my solution

Workflow:

Spoiler

Macro:

Spoiler

Challenge_123 Solution.yxzp

Tim_Palmer

This solution doesn't account for the point at which the rabbits born in month 2, 3, 4, 5, etc become 4 months old, meaning they can now give birth every month, only the original population, so it assumes all Rabbits "age>3" can all give birth when there should be a delay for every new litter.

Tim_Palmer

Hi there,

I worked this one out in excel first as I'm very new to alteryx (see attached) and it looks to me like your solution may be incorrect. Can you point out where your solution does the following:

- removes the females born in the preceding three months from the previous month's total rabbit population as they are too young to procreate, before calculating the number of males and females that are born in the current month and adding the number onto the previous month's rabbit population for the new total

- subtracts the number of rabbits that die (born in the -24)each month as part of the total rabbit population calculation before feeding into the above

I'm very new to alteryx and I'd love to understand where these elements are in your file.

Many thanks

weekly challenge rabbits v2.xlsx

Beastmode314

My Solution. So, I took a different approach and decided to do this without using macros. Let me know what you think.

challenge_123_Solution_CL.yxmd

Ruud

You had my curiousity, but now you have my attention: why do those conversion errors happen? The field type is set to int64, but the Multi-Row uses a float. However, those values should fit in a float, so: are these floating-point errors? @JoeM?

patrick_digan

@Tim_Palmer I've modified your spreadsheet to match the provided solution. It's just a difference of opinion on the timing of births and deaths.

weekly challenge rabbits v2.xlsx

patrick_digan

@Beastmode314 Impressive that you got that close with some generate rows tools!

Prab

First Iterative macro... Thanks to the first two responses.

Solution attached.

challenge_123_start_file_PRB.yxzp

KevinW

Fun Challenge, solved with an iterative macro also.

However, I feel that the world's population is larger than the 326 million or so in the text input (could this be the population of the USA?).

challenge_123_solution_file.yxmd

bunny macro.yxmc

KOBoyle

Solution attached.

I have to agree with those that came up with 2022-01-02 as the Date, and I don't think there is any ambiguity in the problem. The problem states that Age 0 occurs on the birthdate, not the following month, and that the frequency for each new generation is 4 months not 5. Also, in July the initial births are included in the population count, so all subsequent births should be added to the population in the month of birth. Just counting on my fingers with July = Month 0, the first litter should arrive in November with a new generation every Mar and July after that. In the solution provided, the first litter doesn't arrive until December, and then every 5 months (May, Oct, …) after that. I think where the solution is flawed is that in the current month it calculates new births, and then passes that as an 'Age 0' population to the iteration for the next month. In reality, there is no Age 0 population, the new births should be added to the population in the birth month, and passed to the next iteration as Age 1 population.