Question

I have 2 lists, and inside each are two more lists containing data frames (in other words, nested lists). I want plot each data frame and title it based on the names of both the primary and nested lists.

For example, say we have:

a=list(
  list(a=data.frame(x=rpois(5,1),y=rpois(5,1)),
       b=data.frame(x=rpois(5,1),y=rpois(5,1))),
  list(c=data.frame(x=rpois(5,1),y=rpois(5,1)),
       d=data.frame(x=rpois(5,1),y=rpois(5,1))))

And we have the names of the primary list:

names(a)=c("alpha","bravo")

Inside the two primary lists alpha and bravo, we have two more lists, charlie and delta:

for(i in 1:length(a)) {
  names(a[[i]])=c("charlie","delta") }

I can use lapply to loop through each list and plot the data frames, but I am having trouble getting the titles to combine the name of the primary list (alpha and bravo) and the nested list (charlie and delta) for each data frame. For instance, in this case, I would like to have four plots called: alpha_charlie, alpha_delta,bravo_charlie, and bravo_delta.

lapply(a,function(i) {
  lapply(names(i), function(j) { 
    ggplot()+
      geom_point(data=i[[j]],aes(x,y))+
      opts(title=paste(names(i),j,sep="_")) #Here is where I am struggling!
    } ) } )

Any help would be much appreciated. Thank you!

Answer 1

You could use lapply on an indexing sequence instead of the names themselves.

lapply(seq(a), function(i){
    lapply(seq(a[[i]]), function(j){
        ggplot() +
        geom_point(data = a[[i]][[j]], aes(x, y))+
        opts(title = paste(names(a)[i], names(a[[i]])[j], sep = "_"))
        })})