Home Altering arrays to add/remove entries at each time-step in R
 This question, probably has a simple solution but I cannot think of how to do it... So I have a script as follows: # ------------------ MODEL SETUP ----------------------------------------# simulation length t_max <- 50 # arena arena_x <- 100 arena_y <- 100 # plant parameters a <- 0.1 b <- 0.1 g <- 1 # list of plant locations and initial sizes nplants <-dim(plantLocsX)[1]*dim(plantLocsX)[2] iterations<-5 totalBiomass<-matrix(0,nrow=iterations,ncol=1) # starting loop sep <- 10 # Original matrix plantLocsX <- matrix(rep(seq(0,arena_x,sep), arena_y/sep), nrow=1+arena_x/sep, ncol=1+arena_y/sep) plantLocsY <- t(plantLocsX) plantSizes <- matrix(1,nrow=nplants,ncol=1) # Plot the plants radius <- sqrt( plantSizes/ pi ) symbols(plantLocsX, plantLocsY, radius, xlim = c(0,100), ylim=c(0,100), inches=0.05, fg = "green", xlab = "x domain (m)", ylab = "y domain (m)", main = "Random Plant Locations", col.main = 51) # Calculate distances between EACH POSSIBLE PAIR of plants distances <- matrix(0,nrow=nplants,ncol=nplants) for (i in 1:nplants){ for (j in 1:nplants){ distances[i,j] <- sqrt( (plantLocsX[i]-plantLocsX[j])^2 + (plantLocsY[i]-plantLocsY[j])^2 ) } } # ------------------ MODEL RUNNING ---------------------------------------  I need to alter the arrays containing plant locations and plant sizes so that at each time step, entries are removed and added (simulating mortality/reproduction, respectively). The "distances" must be updated with plant locations and sizes after each iteration...I can only think of complex ways to do this: destructing and constructing new matrices at each time step to fit the new number of elements but there must be functions to make this simpler....any advice? Many thanks!!