r - 如何向 ggpairs() 添加外部图例？

Question

我正在使用 ggpairs 绘制散点图矩阵.我正在使用以下代码:

# 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)

我得到以下情节:



现在，人们可以很容易地看到，我为矩阵中的每个图都得到了图例。我希望整个情节只有一个普遍的传说。我怎么做？
任何帮助将非常感激。

Answer 1

我正在做类似的事情，这是我会采取的方法，

确保在 ggpairs 中将图例设置为“TRUE”函数调用

现在迭代绘图矩阵中的子图并删除它们中的每一个的图例，只保留其中一个，因为密度都绘制在同一列上。

colIdx <- c(3,5,6,7)

for (i in 1:length(colIdx)) {

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

  # Add any ggplot2 settings you want (blank grid here)
  inner <- inner + theme(panel.grid = element_blank()) +
    theme(axis.text.x = element_blank())

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

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

      # Move legend right
      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 legend
      inner <- getPlot(p, i, j)
      inner <- inner + theme(legend.position="none")
      p <- putPlot(p, inner, i, j)
    }
  }
}