R code error in lenght of time

[user124578]

Please, can someone shed some light to what is wrong with my code? I am getting an error message
Error in t_store[count_times] <- cumsum(y_store)[length(y_store)] :
replacement has length zero

I am trying to get a sequence of times intervals using the lambda for a Uniform distribution.

Many Thanks

Question4 = function(lambda) {
  # store each time generated by rexp
  y_store = c()
  # store the time of each patient
  t_store = c(1)
  
  # count the index of vector above
  count_times = 1
  # Loop of the Time until it exceeds 12
  while (t_store[length(t_store)] <= 12) {
    # Generate time to follow exp randomly
    arrivals = dunif(rexp(0.1, lambda))
    # store the each time generated by rexp
    y_store[count_times] = arrivals
    # Store the time for each patient's arrival
    t_store[count_times] = cumsum(y_store)[length(y_store)]
    # Index to next element in vector
    count_times = count_times + 1
    
  }
  # Return the time stored for each patient
  return (t_store)
  
}

main_Question4 = function() {
  lambda = 10
  # Get the arrival time
  arr_times = Question4(10)
  # Get the number of the people
  num_Peo = (1:length(arr_times))
  
  #Plot the of the time of the patients
  plot(
    num_Peo,
    arr_times ,
    main = 'Arrival Times',
    xlab = 'The i-th Patient',
    ylab = 'Arrival Time of The i-th Patient ',
    col = 'red'
  )
  
}

main_Question4() 

[raytong]

Hi @user124578. The problem due to rexp function. You may shift the two arguments.

Question4 = function(lambda) {
  # store each time generated by rexp
  y_store = c()
  # store the time of each patient
  t_store = c(1)
  
  # count the index of vector above
  count_times = 1
  # Loop of the Time until it exceeds 12
  while (t_store[length(t_store)] <= 12) {
    # Generate time to follow exp randomly
    arrivals = dunif(rexp(lambda, 0.1))
    # store the each time generated by rexp
    y_store[count_times] = arrivals
    # Store the time for each patient's arrival
    t_store[count_times] = cumsum(y_store)[length(y_store)]
    # Index to next element in vector
    count_times = count_times + 1
    
  }
  # Return the time stored for each patient
  return (t_store)
  
}

main_Question4 = function() {
  lambda = 10
  # Get the arrival time
  arr_times = Question4(10)
  # Get the number of the people
  num_Peo = (1:length(arr_times))
  
  #Plot the of the time of the patients
  plot(
    num_Peo,
    arr_times ,
    main = 'Arrival Times',
    xlab = 'The i-th Patient',
    ylab = 'Arrival Time of The i-th Patient ',
    col = 'red'
  )
  
}

main_Question4() 

^{Created on 2019-10-09 by the reprex package (v0.3.0)}

[user124578]

Thanks very much for your help