R - save multiplot to file

Question

I’d really appreciate your help with the following problem. I know several ways to save a single plot to a file. My question is: How do I correctly save a multiplot to a file?

To begin with, I’m not an experienced R user. I use ggplot2 to create my plots, and another thing I should probably mention is that I use the RStudio GUI. Using an example from the R Cookbook, I'm able to create multiple plots in one window.

I would like to save this so-called multiplot to a file (preferably as jpeg), but somehow fail to do this.

I’m creating the multiplot as follows:

##define multiplot function
    multiplot <- function(..., plotlist=NULL, cols) {
        require(grid)

        # Make a list from the ... arguments and plotlist
        plots <- c(list(...), plotlist)

        numPlots = length(plots)

        # Make the panel
        plotCols = cols                          # Number of columns of plots
        plotRows = ceiling(numPlots/plotCols) # Number of rows needed, calculated from # of cols

        # Set up the page
        grid.newpage()
        pushViewport(viewport(layout = grid.layout(plotRows, plotCols)))
        vplayout <- function(x, y)
            viewport(layout.pos.row = x, layout.pos.col = y)

        # Make each plot, in the correct location
        for (i in 1:numPlots) {
            curRow = ceiling(i/plotCols)
            curCol = (i-1) %% plotCols + 1
            print(plots[[i]], vp = vplayout(curRow, curCol ))
        }

    }

## define subplots (short example here, I specified some more aesthetics in my script)
plot1a <- qplot(variable1,variable2,data=Mydataframe1)
plot1b <- qplot(variable1,variable3,data=Mydataframe1)  
plot1c <- qplot(variable1,variable2,data=Mydataframe2)
plot1d <- qplot(variable1,variable3,data=Mydataframe2)  

## plot in one frame
Myplot <- multiplot(plot1a,plot1b,plot1c,plot1d, cols=2)

This gives the desired result. The problem arises when I try to save to a file. I can do this manually in RStudio (using Export -> Save plot as image), but I would like to run everything in a script. I manage to save only subplot1d (which is last_plot()), and not the complete multiplot.

What I’ve tried so far:

Using ggsave
```
ggsave(filename = "D:/R/plots/Myplots.jpg")
```
This results in only subplot 1d being saved.
Using jpeg(), print() and dev.off()
```
jpeg(filename = "Myplot.jpg", pointsize =12, quality = 200, bg = "white", res = NA, restoreConsole = TRUE)
print(Myplot)
dev.off()
```
This results in a completely white image (just the background I assume). print(Myplot) returns NULL.

Not sure what I’m doing wrong here. My lack of understanding R is the reason I am stuck trying to find a solution. Can anyone explain what I’m doing wrong and perhaps suggest a way to solve my problem(s)?

R - save multiplot to file

3 Answers