CODEWITHSUNDEEP
rfor-loopmultiple-columnslapply
Drew
Drew

Reputation: 593

list of dataframes to a list of plots; for loops, lapply

I have a list of dataframes in Rlist as such:

Rlist = lapply(1:5,function(i){
  data.frame(Frame_times = seq(0,1,length.out=100),L1=runif(100), L2 = runif(100), L3 = runif(100))
})
names(Rlist) = letters[1:5]

As you can see, there is a list containing 5 dataframes. Within each dataframe, there are three columns called L1, L2, and L3. I want to use these three columns from each dataframe to create plots (specifically, spectral analysis plots), and I want to do this systematically using loops.

The ineffective code below tries to do the following: Creates plots using the three columns of interest inside each dataframe in Rlist, and puts them in a new list called aplotfinal. In the end, I should have a list of lists that contain plots called aplotfinal, with 15 plots in total, but more specifically, 5 lists with 3 plots per list.

aplotfinal <- lapply(1:length(Rlist),function(i){
  a <- Rlist[[i]][,-1]
  for(t in colnames(a)){
    del <- 0.016667 
    x.spec <- spectrum(a$t, log = "no", plot = FALSE) 
    spx <- x.spec$freq/del
    spy <- 2*x.spec$spec 
    aplotfinal[[i]] <- qplot(y = spy,x=spx,geom="line") + 
      ggtitle(names(Rlist)[i]) + 
      xlab("frequency")+ylab("spectral density")
  }
})

Hope this makes sense. Thank you!

Upvotes: 1

Views: 61

Answers (1)

Rui Barradas
Rui Barradas

Reputation: 76450

The following code is the question's code corrected. It outputs a list with 5 members, each a list with 3 plots.

aplotfinal <- lapply(1:length(Rlist),function(i){
  a <- Rlist[[i]][,-1]
  lapply(colnames(a), function(t){
    del <- 0.016667 
    x.spec <- spectrum(a[[t]], log = "no", plot = FALSE) 
    spx <- x.spec$freq/del
    spy <- 2*x.spec$spec 
    qplot(y = spy,x=spx,geom="line") + 
      ggtitle(names(Rlist)[i]) + 
      xlab("frequency")+ylab("spectral density")
  })
})

To see the first plot of the first sub-list:

aplotfinal[[1]][[1]]

enter image description here

Upvotes: 2

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