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Roulette Tracking
I have a spreadsheet where I count the results of spins on a Roulette wheel. How can I track the number of spins since the last time a specific result occurred? For example, how many spins has it bee...
This is, frankly, playtime! It uses range composition to build subsets taken from the results range. Sample worksheet formulas are
= LET(
Fnλ, LAMBDA(x, x),
MAP(result, SpinCounter(Fnλ))
)
and
= LET(
Fnλ, LAMBDA(x, IF(x, ISEVEN(+x), "zero")),
MAP(result, SpinCounter(Fnλ))
)which give results for the winning number and even/odd respectively.
A function Fnλ should be defined to return a unique value for each category of interest, even/odd, black/red etc. MAP passes one cell at a time to SpinCounter(Fnλ).
SpinCounter
= LAMBDA(Fnλ, LAMBDA(current,
// "Fnλ is a function that maps results to distinct roulette categories"
// "current is a specific cell taken from the array of results"
LET(
//"Define results up to but not including the current cell as a range"
priorResults, DROP(top:current, -1),
//"Look up cell mapping within the mapped array"
priorMatch, XLOOKUP(Fnλ(current), Fnλ(priorResults), priorResults,,,-1),
//"Count the results between the current cell and its matched prior cell"
count, COUNT(priorMatch:current),
IF(count, count - 1, "")
)
))There is more to do, but that will have to be another day!
Played around a bit further with formulas to determine where a number is red or black and count offsets to prior occurrence.
To return the color
= RedBlackλ(result)
and the count
= MAP(result, SpinCounter(EvenOddλ))
where
RedBlackλ
= LAMBDA(number,
LET(
iseven?, ISEVEN(+number),
isRed?, IF(number, IF(1+MOD(number-1, 18) > 10, iseven?, NOT(iseven?)), "zero"),
SWITCH(isRed?, TRUE, "red", FALSE, "black", "green")
)
);