How to save several plots from an own function into a list in R?

Question

I have created one function that contains two types of plots and it will give you one image. However, the title of this image will change depending on one list, so, you will have several plots but different title. (The original function will change the numbers that the plot uses but, in essence, is what I need).

This is the example that I have created.

list_genes <- c("GEN1", "GEN2", "GEN3")


myfunction <- function(x,y){
  
  for(gene in list_genes){
    # This to draw both plots
      par(mfrow=c(2,1))  
      
      plot(x,y, main=paste0("Plot of ", gene))
      
      hist(x, main=paste0("Plot of ", gene))
  }
}

myfunction(x=c(1,5,6,2,4),y=c(6,10,53,1,5))

Since the list has 3 elements, we get 3 plots.

However, as I need to create a presentation with all the plots that I generate, I found this post with a solution to create slides for several plots inside a for loop. It is what I want, but for that, I need to save my plots into a list/variable.

object <- myfunction(x=c(1,5,6,2,4),y=c(6,10,53,1,5))
> object
NULL

I found this post (which gives you an interesting solution) but, the plots still cannot be saved into an object.

calling_myfunc <- function(){
  myfunction(x=c(1,5,6,2,4),y=c(6,10,53,1,5))
}

calling_myfunc()

object <- calling_myfunc()
> object
NULL

My final objective is to create a presentation (automatically) with all of the plots that I generate from my function. As I saw in this post. But I need to save the plots into a variable.

Could anyone help me with this?

Thanks very much in advance

Unfortunately base R plots don’t really have a good mechanism to save plot objects (there is a way via `recordPlot` as shown in the post you’ve linked, but it’s rather convoluted). By contrast, ‘ggplot2’ makes this trivial. I therefore strongly recommend you use ‘ggplot2’. — Konrad Rudolph, Nov 10 '21 at 16:01
@Konrad Rudolph I tried `recordPlot` but I don't really know how it is working. It generates the plot again, but it shows the first one. In the example that I added, it shows the 3 plots, then an empty image and then the third plot. I don't really know how it is working. In my original function I use the functions stripchart() and hist(). I didn't know that base R plots had problems to save objects... — emr2, Nov 10 '21 at 16:21

emr2 · Accepted Answer · 2021-11-19T08:31:27.073

Although I couldn't find the way to save the plots into an object, I found a way to create a presentation with those images thanks to this post and the export package.

library(export) 

list_genes <- c("GEN1", "GEN2", "GEN3")


myfunction <- function(x,y){
     for(gene in list_genes){
    # This to draw both plots
      par(mfrow=c(2,1))  
      
      plot(x,y, main=paste0("Plot of ", gene))
      
      hist(x, main=paste0("Plot of ", gene))
      graph2ppt(file="plots.pptx", width=6, height=5,append=TRUE)    } }

myfunction(x=c(1,5,6,2,4),y=c(6,10,53,1,5))

Of course, the width and height of the plots can be changed or put them as a parameter in the function.

Since the package is not available in CRAN for my current R version (4.1.2), I downloaded it from GitHub: devtools::install_github("tomwenseleers/export")

In addition, I have found another package that I can use for the same purpose (although it adds one extra slide at the beginning, I don't know why)

library(eoffice)

list_genes <- c("GEN1", "GEN2", "GEN3")


myfunction <- function(x,y){
  
  for(gene in list_genes){
    # This to draw both plots
      par(mfrow=c(2,1))  
      
      plot(x,y, main=paste0("Plot of ", gene))
      
      hist(x, main=paste0("Plot of ", gene))
      topptx(file="plots.pptx", width=6, height=5,append=TRUE) 
  }
}

myfunction(x=c(1,5,6,2,4),y=c(6,10,53,1,5))

PS: I found the solution to create a presentation --> How to create a presentation in R with several plots obtained by a function?

How to save several plots from an own function into a list in R?

1 Answers1