Legend using ggpairs

Question

Trying to follow an example made here, I was reproducing the following code:

# Load required packages
require(GGally)

# Load datasets
data(state)
df <- data.frame(state.x77,
                 State = state.name,
                 Abbrev = state.abb,
                 Region = state.region,
                 Division = state.division
) 
# Create scatterplot matrix
p <- ggpairs(df, 
             # Columns to include in the matrix
             columns = c(3,5,6,7),

             # What to include above diagonal
             # list(continuous = "points") to mirror
             # "blank" to turn off
             upper = "blank",
             legends=T,

             # What to include below diagonal
             lower = list(continuous = "points"),

             # What to include in the diagonal
             diag = list(continuous = "density"),

             # How to label inner plots
             # internal, none, show
             axisLabels = "none",

             # Other aes() parameters
             colour = "Region",
             title = "State Scatterplot Matrix"
) 

# Show the plot
print(p)

I was supposed to get an image with legend for each plot.

But instead, I am getting one without any legend.

Any tips of why the image I am getting does not have the legends? My particular case needs them!

I am using R v. 3.2.2, and tried both in RStudio and RGui.

Thanks in advance!

Answer 1

There should be a standard way to to it, but I could not find one. The old print function is still there and accessible but as in internal function. Try this instead of the print:

  GGally:::print_ggpairs_old(p)

And if you add this (thanks to this post answer Legend using ggpairs )

colidx <- c(3,5,6,7)
for (i in 1:length(colidx)) {

  # Address only the diagonal elements
  # Get plot out of plot-matrix
  inner <- getPlot(p, i, i);

  # Add ggplot2 settings (here we remove gridlines)
  inner <- inner + theme(panel.grid = element_blank()) +
    theme(axis.text.x = element_blank())

  # Put it back into the plot-matrix
  p <- putPlot(p, inner, i, i)

  for (j in 1:length(colidx)){
    if((i==1 & j==1)){

      # Move the upper-left legend to the far right of the plot
      inner <- getPlot(p, i, j)
      inner <- inner + theme(legend.position=c(length(colidx)-0.25,0.50)) 
      p <- putPlot(p, inner, i, j)
    }
    else{

      # Delete the other legends
      inner <- getPlot(p, i, j)
      inner <- inner + theme(legend.position="none")
      p <- putPlot(p, inner, i, j)
    }
  }
}

You get something much better: