Plot two Graphs on Same Chart R, ggplot2 par(mfrow())

Question

I am getting the feeling after doing some digging that this probably will not work and I will need to discover an alternate method but I am going to ask anyways.

I have to graphs that I want to plot on the same chart, by making use of par(mfrow=c(1,2))

My code for the graphs is as follows:

mTotal <- mean(data$Total)
mTotal

data$valence1[data$Total >= mTotal] <- "Above Mean"
data$valence1[data$Total < mTotal] <- "Below Mean"
data$valence2[data$Delta >= 0] <- "Positive"
data$valence2[data$Delta < 0] <- "Negative"

data

par(mfrow=c(1,2))

ggplot(data,
       aes(x = Index,
           y = Total,
           fill = valence1)) +
  geom_bar(stat = "identity",
           colour = "black",
           alpha = 0.618) +
  geom_hline(yintercept = mTotal,
             linetype = "dashed",
             colour = "red") + 
  annotate("text", x = 19, y = mTotal + 50,
           label = "Problem Period") + 
  xlab("Date") + 
  ylab("Ambulance Arrivals") +
  ggtitle("Ambulance Arrivals by Month
          Jan 2013 - Feb 2014")

maxDelta <- max(data$Delta)
maxDelta
minDelta <- min(data$Delta)
minDelta

ggplot(data,
       aes(x = Index,
           y = Delta,
           fill = valence2)) +
  geom_bar(stat = "identity",
           position = "identity",
           colour = "black",
           alpha = 0.618) +
  annotate("rect", xmin = 13.5, xmax = 24.5,
           ymin = minDelta, ymax = maxDelta,
           alpha = 0.3, fill = "blue") +
  annotate("text", x = 19, y = maxDelta + 25,
           label = "Problem Period") +
  xlab("Date") +
  ylab("Change in Arrivals") + 
  ggtitle("Change in Ambulance Arrivals Month over Month")

If this is not possible, then a direction to a better route would be appreciated.

Thank you,

Answer 1

Look at the gridExtra package and use grid.arrange instead. Works wonderfully with ggplot.

Just assign your first ggplot call to a variable (e.g. plot1) and the next to another (e.g. plot2) and do something like:

grid.arrange(plot1, plot2, nrow=1, ncol=2)

Answer 2

mfrow is for use with base graphics. For ggplot2 you need a different approach, like the one mentioned by @hrbmstr, or this one:

library("ggplot2")
library("grid")

a <- qplot(x = rnorm(10))
b <- qplot(x = rnorm(10))

vplayout <- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)

grid.newpage()
pushViewport(viewport(layout = grid.layout(1, 2)))

print(a, vp = vplayout(1,1))
print(b, vp = vplayout(1,2))

Answer 3

Late to the party, but I just had to deal with this and found a simple solution for multiplots simply by looking in the in the gridExtra package (builind on @hrbrmstr):

library("ggplot2")
library("gridExtra")
pl <- lapply(1:4, function(.x) qplot(1:10, rnorm(10), main=paste("plot", .x)))
marrangeGrob(pl, nrow=2, ncol=2)

Just put you plot generating function in the lapplyand you're all set.