Simulating Failure of Engines in R

General
1

Here is my R code for 5 engine failures in parallel: all engines start with a failure probability of 0.5...each turn the probability of failure increases by 0.01 ... when it fails for the first time, its out forever. This continues until all 5 engines have failed:

    engines <- paste0("engine_", 1:5)  
prob_working <- 0.5

max_turns <- 100  

df <- data.frame(matrix(ncol = 11, nrow = max_turns))
colnames(df) <- c("turn", paste0("engine_", 1:5), paste0("engine_", 1:5, "_prob"))

for (i in seq_along(.engines)) {
    engine <- .engines[i]
    turn <- 1
    while(turn <= max_turns) {
        result <- ifelse(runif(1) < prob_working, "working", "failure")
        
        df[turn, "turn"] <- turn
        df[turn, engine] <- result
        df[turn, paste0(engine, "_prob")] <- prob_working
        
        if (result == "failure") {
            break
        }
        
        prob_working <- prob_working - 0.01
        
        prob_working <- max(prob_working, 0)
        
        turn <- turn + 1
    }
    

    if (df[turn, engine] == "failure") {
        prob_working <- 0.5
    }
}


df <- df[1:max(df$turn, na.rm = TRUE), ]
df

See below:

 turn engine_1 engine_2 engine_3 engine_4 engine_5 engine_1_prob engine_2_prob engine_3_prob engine_4_prob engine_5_prob
1    1  failure  failure  working  failure  working           0.5           0.5          0.50           0.5          0.50
2    2     <NA>     <NA>  failure     <NA>  working            NA            NA          0.49            NA          0.49
3    3     <NA>     <NA>     <NA>     <NA>  working            NA            NA            NA            NA          0.48
4    4     <NA>     <NA>     <NA>     <NA>  failure            NA            NA            NA            NA          0.47

How can I change this code so that at the start of each turn, we look at how many engines have failed ... and the remaining engines from now on will have a failure probability of 0.01 * (n+1) , where n = number of failed engines?

2

You currently loop over engines in the outer loop and turns in the inner loop. You will need to rewrite the code with those loops reversed (engines nested inside turns).

1 Like
3

thank you ... any chance you can help me do this if you have time please?

4

Sorry, no. Too many things to do, too many people to do them to.