ggplot2 : printing multiple plots in one page with a loop
ggplot2, gridextra, loops, r
Solution
Your error comes from indexing a list with `[[`:
consider
pl = list(qplot(1,1), qplot(2,2))
`pl[[1]]` returns the first plot, but `do.call` expects a list of arguments. You could do it with, `do.call(grid.arrange, pl[1])` (no error), but that's probably not what you want (it arranges one plot on the page, there's little point in doing that). Presumably you wanted all plots,
grid.arrange(grobs = pl)
or, equivalently,
do.call(grid.arrange, pl)
If you want a selection of this list, use `[`,
grid.arrange(grobs = pl[1:2])
do.call(grid.arrange, pl[1:2])
Further parameters can be passed trivially with the first syntax; with `do.call` care must be taken to make sure the list is in the correct form,
grid.arrange(grobs = pl[1:2], ncol=3, top=textGrob("title"))
do.call(grid.arrange, c(pl[1:2], list(ncol=3, top=textGrob("title"))))
Problem
I have several subjects for which I need to generate a plot, as I have many subjects I'd like to have several plots in one page rather than one figure for subject. Here it is what I have done so far: Read txt file with subjects name ``` subjs <- scan ("ListSubjs.txt", what = "") ``` Create a list to hold plot objects ``` pltList <- list() for(s in 1:length(subjs)) { setwd(file.path("C:/Users/", subjs[[s]])) #load subj directory ifile=paste("Co","data.txt",sep="",collapse=NULL) #Read subj file dat = read.table(ifile) dat <- unlist(dat, use.names = FALSE) #make dat usable for ggplot2 df <- data.frame(dat) pltList[[s]]<- print(ggplot( df, aes(x=dat)) + #save each plot with unique name geom_histogram(binwidth=.01, colour="cyan", fill="cyan") + geom_vline(aes(xintercept=0), # Ignore NA values for mean color="red", linetype="dashed", size=1)+ xlab(paste("Co_data", subjs[[s]] , sep=" ",collapse=NULL))) } ``` At this point I can display the single plots for example by ``` print (pltList[1]) #will print first plot print(pltList[2]) # will print second plot ``` I d like to have a solution by which several plots are displayed in the same page, I 've tried something along the lines of previous posts but I don't manage to make it work for example: ``` for (p in seq(length(pltList))) { do.call("grid.arrange", pltList[[p]]) } ``` gives me the following error `Error in arrangeGrob(..., as.table = as.table, clip = clip, main = main, : input must be grobs!` I can use more basic graphing features, but I d like to achieve this by using ggplot. Many thanks for consideration Matilde