Side-by-side plots with ggplot2

Question

I would like to place two plots side by side using the ggplot2 package, i.e. do the equivalent of par(mfrow=c(1,2)).

For example, I would like to have t

Answer 1

The above solutions may not be efficient if you want to plot multiple ggplot plots using a loop (e.g. as asked here: Creating multiple plots in ggplot with different Y-axis values using a loop), which is a desired step in analyzing the unknown (or large) data-sets (e.g., when you want to plot Counts of all variables in a data-set).

The code below shows how to do that using the mentioned above 'multiplot()', the source of which is here: http://www.cookbook-r.com/Graphs/Multiple_graphs_on_one_page_(ggplot2):

plotAllCounts <- function (dt){   
  plots <- list();
  for(i in 1:ncol(dt)) {
    strX = names(dt)[i]
    print(sprintf("%i: strX = %s", i, strX))
    plots[[i]] <- ggplot(dt) + xlab(strX) +
      geom_point(aes_string(strX),stat="count")
  }

  columnsToPlot <- floor(sqrt(ncol(dt)))
  multiplot(plotlist = plots, cols = columnsToPlot)
}

Now run the function - to get Counts for all variables printed using ggplot on one page

dt = ggplot2::diamonds
plotAllCounts(dt)

One things to note is that:
using aes(get(strX)), which you would normally use in loops when working with ggplot , in the above code instead of aes_string(strX) will NOT draw the desired plots. Instead, it will plot the last plot many times. I have not figured out why - it may have to do the aes and aes_string are called in ggplot.

Otherwise, hope you'll find the function useful.