[R] plots

I would like to have a plot with values in a reversed order (as shown in fig 2). I tried to plot the graph in R using the following codes plot(density,depth,pch=as.numeric(species),xlab="fish density (#/m2)",ylab="water depth (m)") legend(locator(n=1),legend=c("Tropheus brichardi","Petrochromis

[R] plots

I would like to have a plot with values in a reversed order (as shown in fig 2). I tried to plot the graph in R using the following codes plot(density,depth,pch=as.numeric(species),xlab="fish density (#/m2)",ylab="water depth (m)") legend(locator(n=1),legend=c("Tropheus brichardi","Petrochromis

[R] logistic growth model

I want to Fit a logistic growth model for y = k *eb0+b1(age)/1 + eb0+b1(age), can some one help on how to get the initial coefficients b0 and b1? I need to estimate in order to do the regression analysis. When I run using b0=0.5 and b1=3.4818, I get the following error 397443.8 : 0.5 3.4818