R'ggplot2'将常见和唯一的图例与多个(网格化的)绘图对象一起排列. [英] R 'ggplot2' Arranging common and unique legends with multiple (gridded) plot objects.

问题描述

编辑-以下包含可复制的示例

我一直在使用此功能和ggplot2软件包一起添加到为组合的ggplots添加通用图例当每个情节只有一种类型的图例时，它可以完美地工作，例如对于...,color =, ....

I have been using this function with the ggplot2 package to Add a common Legend for combined ggplots which works perfecty when each plot has only 1 type of legend e.g. for ...,color =, ....

但是，我试图排列多个具有相同图例的图，但每个图都有一个额外的独特图例，例如:

However, I am trying to arrange multiple plots which share a common legend but each has an additional unique legend e.g.:

  ggplot(df1, aes(x=Site, y=RESULT, color=Position , shape=DETNAME)) +
        geom_point(size=5) + ylab ("concentration (mg/L)") +
        labs (shape = "Determinand")

产生:

我有3倍的位置图例共享，但Determinand图例是唯一的.

I have 3x these where the Position legend is shared but the Determinand legends are unique.

所以我想知道是否还有一个我可以传递给grid_arrange_shared_legend()的参数，该参数将保留Determinand图例(shape = DETNAME)，即使用legend.position = "top"之类的图形将它们绘制在网格的每个图上方，位置(color = position)的常见图例?

So I want to know if there is an additional argument I can pass to grid_arrange_shared_legend() which will preserve the Determinand legends (shape = DETNAME) i.e. plotting them above each plot on the grid using something like legend.position = "top" but having a common legend for Position (color = position) ?

我知道我可以将+ guides(shape = FALSE )添加到每个绘图对象，然后使用grid_arrange_shared_legend()，这给了我共享的位置图例，但是我想实现类似的功能，但是每个绘图都具有唯一的Determinand图例:

I know I can add + guides(shape = FALSE ) to each plot object and then use grid_arrange_shared_legend() which gives me the shared Position legend, but I want to achieve something like this but with a unique Determinand legend for each plot:

或者有人可以建议grid_arrange_shared_legend()函数的源代码的哪一部分需要编辑才能执行?

Or could any one advise which part of the source code for the grid_arrange_shared_legend() function needs editing to perform this?

编辑-可复制的示例

  library (ggplot2)
  library(gridExtra)
  library (grid)

   # two ggplot plot objects with multiple legends 1 common legend and 2 unique

  p1<- ggplot(diamonds, aes(x=price, y= depth, color= clarity , shape= cut )) +
    geom_point(size=5) + labs (shape = "unique legend", color = "common legend")

  p2 <- ggplot(diamonds, aes(x=price, y= depth, color= clarity , shape= color )) +
 geom_point(size=5) + labs (shape = "unique legend", color = "common legend")

   # shared legend function

  grid_arrange_shared_legend <- function(..., ncol = length(list(...)), nrow     = 1, position = c("bottom", "right")) {

    plots <- list(...)
    position <- match.arg(position)
    g <- ggplotGrob(plots[[1]] + theme(legend.position = position))$grobs
    legend <- g[[which(sapply(g, function(x) x$name) == "guide-box")]]
    lheight <- sum(legend$height)
    lwidth <- sum(legend$width)
    gl <- lapply(plots, function(x) x + theme(legend.position="none"))
    gl <- c(gl, ncol = ncol, nrow = nrow)

    combined <- switch(position,
                 "bottom" = arrangeGrob(do.call(arrangeGrob, gl),
                                        legend,
                                        ncol = 1,
                                        heights = unit.c(unit(1, "npc") -  lheight, lheight)),
                       "right" = arrangeGrob(do.call(arrangeGrob, gl),
                                       legend,
                                       ncol = 2,
                                       widths = unit.c(unit(1, "npc") - lwidth, lwidth)))

    grid.newpage()
    grid.draw(combined)

    # return gtable invisibly
    invisible(combined)

    }

    grid_arrange_shared_legend (p1,p2)

在这里使用grid_arrange_shared_legend()函数意味着唯一的图例仅对网格上的其中一个图是正确的

Using the grid_arrange_shared_legend() function here means that the unique legend is correct only for one of the plots on the grid

问题:如何保存(提取?)独特的图例并将其绘制在网格上的每个图上方，但将公共图例保留在底部?

Question How to preserve (extract?) the unique legends and plot them above each plot on the grid but keep the common legend at the bottom?

推荐答案

我建议在这里使用cowplot.在这种情况下，最简单的方法是合并两个plot_grid调用，然后使用get_legend获取图例:

I would advise using cowplot here. In this case it's easiest to combine two plot_grid calls, then get the legend with get_legend:

library(ggplot2)

#reduce the number of points to plot
diamonds2 <- diamonds[sample(nrow(diamonds), 500), ]

p1<- ggplot(diamonds2, aes(x=price, y= depth, color= clarity , shape= cut )) +
  geom_point(size=5) + labs (shape = "unique legend", color = "common legend") +
  theme(legend.position = "top")

p2 <- ggplot(diamonds2, aes(x=price, y= depth, color= clarity , shape= color )) +
  geom_point(size=5) + labs (shape = "unique legend", color = "common legend") +
  theme(legend.position = "top")

cowplot::plot_grid(
  cowplot::plot_grid(
    p1 + scale_color_discrete(guide = FALSE),
    p2 + scale_color_discrete(guide = FALSE),
    align = 'h'
  ),
  cowplot::get_legend(p1 + scale_shape(guide = FALSE) + theme(legend.position = "bottom")),
  nrow = 2, rel_heights = c(4, 1)
)

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