# writing a loop in R - new to R and really struggling to understand

I have this basic stage-structured life-cycle model (below) and am trying to figure out how to run this for different temperatures - 0 - 20 in increments of 2 - without have to run the model several times. I then want to be able to plot the 'arrival time of individuals into last class' i.e. plot(temp,arrival time)....

nclass <- 100 # number of classes nsteps <- 1000 # number of model steps n0 <- 100 # number of individuals n <- rep(0, nclass) # number of individuals in classes 0 to nclass p <- 0.5 # proportion of individuals that move into next class tau0 <- 120 # time (in days) taken to reach last class at temp=8 degC Tc <- 8 # characteristic temp temp <- 8 # temperature (deg C) n[1] <- n0 m <- n time <- 0 for (i in 1:nsteps) { j <- nclass n[j] <- n[j] + p*n[j-1] for (j in (nclass-1):2) { n[j] <- (1-p)*n[j]+p*n[j-1] } j <- 1 n[j] <- (1-p)*n[j] m <- rbind(m, n) tau <- (tau0 * exp(-temp/Tc)/nclass)/p time <- c(time, time[i]+tau) } # I'm not sure how to implement this...I have tried to add in another loop: result <- rep(0,11) for(j in 1:11){ temp <- (j-1)*2 [RUN MODEL HERE] result[j] <- arrival time }

I was given that little extra bit by my supervisor but still don't understand how to fit it in. It may be that that's not exactly what it should be but I've tried a variety of things and can't get it to work.

If anyone can shed some light I'd be really grateful.