here i've managed extract extract time in discrete form such 1,2,3...,50 each simulation of users. but, since there no value interval 20-21 , more, there coding such can add value inside myself? because, if there no reading time interval, means readings same until next interval. coding used below: library(gillespiessa) parms <- c(beta=0.591,sigma=1/8,gamma=1/7) x0 <- c(s=50,e=0,i=1,r=0) <- c("beta*s*i","sigma*e","gamma*i") nu <- matrix(c(-1,0,0, 1,-1,0, 0,1,-1, 0,0,1),nrow=4,byrow=true) set.seed(12345) out <- lapply(x=1:1,fun=function(x) ssa(x0,a,nu,parms,tf=50)$data) out a<-as.data.frame(out) idx <- diff(ceiling(a$v1)) == 1 a[idx,] ## change ==1 >0 idx <- diff(ceiling(a$v1)) > 0 ## discrete time series discrete.data <- a[idx,] ## last time step value end.time <- ceiling(tail(discrete.data$v1,1)) ## create empty data frame time steps new.df <- data.frame(t=0:end.time, s=0, e=0, i=0, r=0...