User:DeathFish/RandomWeights Tutorial

Functional statements

• RollChances
• RandomWeightsN

Common misconceptions

What probability does RollChances represent?

RollChances is the probability that a single weighted selection attempt will be executed at all, not the probability that a selected element will be used after being picked.

• Many people confuse it with ExtraWarheads.DetonationChances, which is the probability that an already selected warhead will actually be used (detonated).

The relationship between N and the number of execution rounds

RandomWeightsN is the weight list used for the N-th draw in the current round, not the weight list used for every draw in the N-th round, nor the weight for the N-th element.

Meaning of “the last weight list”

If RandomWeightsX cannot be read, then reading of all subsequent numbered lists stops:

• If RandomWeights/RandomWeights0, RandomWeights1 and RandomWeights3 are defined, but RandomWeights2 and RandomWeights4 are not, then draw 0 uses RandomWeights/RandomWeights0, and draws 1–4 all use RandomWeights1.

Execution flow of the weighted multi‑choice system

Note
The following flow is completed within a single round of usage.

1. Check whether a weight definition exists

• No → Do not perform multi‑choice; continue with default behaviour.
• Yes → Check RollChances: the number of entries in this list determines the number of attempts.
  • If not written, it is treated as RollChances=100%, i.e. one attempt that always succeeds.

2. Use the value in RollChances corresponding to the current attempt to decide whether to draw

• No → Move to the next attempt.
• Yes → Begin a weighted multi‑choice draw.

3. Use the RandomWeights list corresponding to the current attempt to define the weights, and perform the draw

• For attempt 0, use the RandomWeights/RandomWeights0 list.
• For attempt 1, use the RandomWeights1 list.
• If a list is missing for the first time, let this be attempt X; then from this attempt onward, all subsequent draws use RandomWeights[X-1] as the weight list.

4. Has the number of attempts determined by RollChances been reached?

• No → Move to the next attempt.
• Yes → The flow is fully complete.

If, after the draw, there is no additional “use probability” (as in the current Super Weapon random system), every selected item is activated. If there is an additional use probability after the draw (as with ExtraWarheads), then an extra check is performed – for example, with ExtraWarheads, each selected warhead still goes through ExtraWarheads.DetonationChances individually to decide whether it detonates or not.

Summary / supplementary notes

From the flow described above, it can be seen that:

• The number of entries in RollChances determines the number of attempts for the multi‑choice draw.
  • This therefore determines the maximum number of results (super weapons / warheads) that can be drawn.
  • At least one attempt is made – an attempt may fail, so it is possible that no result is drawn at all.

Tip
Writing only RandomWeights/RandomWeights0 without RollChances results in a single weighted draw.

• If the number of entries in a RandomWeightsN list is greater than the number of candidate elements, the extra weight values correspond to “empty”.
  • Example: a single weighted draw has only Types=A but the weight list is RandomWeightsN=1,2,3,4. The chance of drawing A is 1/(1+2+3+4) = 1/10.

• If the number of entries in a RandomWeightsN list is less than the number of candidate elements, elements without a corresponding weight effectively have a weight of 0.
  • Example: a single weighted draw has Types=A,B,C,D (four elements) but the weight list is RandomWeightsN=1. This is equivalent to RandomWeightsN=1,0,0,0, so A is always drawn.
    • If the weight list is changed to RandomWeightsN=25,75, that is equivalent to RandomWeightsN=25,75,0,0. The chance of drawing A is 25/(25+75+0+0) = 1/4, and the chance of drawing B is 75/(25+75+0+0) = 3/4.

Extended usage – simulating DetonationChances-style probabilities with a weight system

Probability table

Type	A	B	C	D	E
DetonationChances	40%	20%	35%	25%	15%

Implementation

[SOMESECTION]
Types=A,B,C,D,E
RollChances=40%,20%,10%,50%,30%
RandomWeights0=1
RandomWeights1=0,1
RandomWeights2=0,0,1
RandomWeights3=0,0,1,1
RandomWeights4=0,0,0,0,1,1

Process walkthrough

With 5 RollChances entries, 5 attempts are made. The outcome of each successful attempt is:

• Attempt 0 (40% success): always selects A (weight list 1)
• Attempt 1 (20% success): always selects B (weight list 0,1)
• Attempt 2 (10% success): always selects C (weight list 0,0,1)
• Attempt 3 (50% success): 50% C, 50% D (weight list 0,0,1,1)
• Attempt 4 (30% success): 50% E, 50% nothing (weight list 0,0,0,0,1,1; index 5 is invalid)

Expected activations

The activation probability for each type is the sum over all attempts of (attempt success rate × probability of selecting that type):

• A: 40% × 100% = 40%
• B: 20% × 100% = 20%
• C: 10% × 100% + 50% × 50% = 10% + 25% = 35%
• D: 50% × 50% = 25%
• E: 30% × 50% = 15%

References

• Phobos documentation - LimboDelivery.
• Phobos documentation - Linked superweapons.
• Phobos documentation - Next.
• Phobos documentation - Extra warhead detonations.