SIR into shiny app

[Laufrech]

Hello everyone,
Can you help me with code below, its SIR model calculated by euler method and I would need to write it into shiny app, so user can input the required data, which will then show the updated plot on the website:

# SIR Euler method

SIR_Euler <- function(S0, I0, R0, beta, gamma, days) {
  # definition of beta, gamma and delta T 
  b <- beta
  g <- gamma
  delta_t <- 0.5
  D <- days
  
  # Definition of N_time for times of aproximation (here every 30 minutes, based on the days from input function)
  nt <- (D*24)/delta_t
  
  #Numeric object + size
  I <- numeric(nt)
  S <- numeric(nt)
  R <- numeric(nt)
  
  mistake <- numeric(nt)
  
  # Setting index 1 and starting value of y0, which then helps to calculate y1 ...
  I[1] <- I0
  S[1] <- S0
  R[1] <- R0
  N <- I0 + S0 + R0
  mistake[1] <- N - (I0 + S0 + R0)
  
  # loop function for calculating aproximation based on days
  n=1
  for (n in 1:(nt)) {
    S[n+1] = S[n] + (-b*S[n]*I[n]*delta_t)
    I[n+1] = I[n] + (b*S[n]*I[n]*delta_t - g*I[n]*delta_t)
    R[n+1] = R[n] + g*I[n]*delta_t
    
    # mistake when making aproximation ... mistake is from equal of N = S(t) + I(t) + R(t)
    mistake[n+1] <- N - (S[n+1]+I[n+1]+R[n+1])
    
  }
  
  
  # table of values of aproximation calculation for every x in interval each step h (30 minutes <--> 0.5h)
  SIR_table <- data.frame(timet = 1:(nt+1), S=S, I=I, R=R, Mistake=mistake, Population=N, Time=D)
  
  
  return(SIR_table)
  
}


SIR_plot <- function(data_table) {
  plot(data_table$timet/48, data_table$S, main="SIR Euler Method", ylab = "Population", xlab = "time (Days)", type="l", col="blue", xlim=c(0, data_table$Time[1]), ylim=c(0, data_table$Population[1]))

  lines(data_table$timet/48, data_table$I, col="red")

  lines(data_table$timet/48, data_table$R, col="green")

  legend("top", c("Susceptible","Infectious","Recovered"), fill=c("blue","red","green"))
}


SIR_plot(SIR_Euler(1000, 1, 0, 0.00002, 0.002, 100))

[hadley]

You can start at https://mastering-shiny.org/basic-app.html to see how to create a basic shiny app.