How to rearrange legends position in phylogenetic tree with multiple associated matrix made by ggtree?

Question

[YiweiZhu]

Hi, everyone! I am using ggtree to make a phylogenetic tree with multiple matrix. I find the legends are arranged in a column. Since I have multiple matrix to plot, the legends column is too long. How can the legends be rearranged in a row? I try the cowplot::get_legend and plot_grid functions. But I cannot shrink the margins between the tree and legends.

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1. A producible example quoted from https://yulab-smu.github.io/treedata-book/chapter7.html#gheatmap

   nwk <- system.file("extdata", "sample.nwk", package="treeio")
   tree <- read.tree(nwk)
   
   circ <- ggtree(tree, layout = "circular")
   df <- data.frame(first=c("a", "b", "a", "c", "d", "d", "a", "b", "e", "e", "f", "c", "f"),
                        second= c("z", "z", "z", "z", "y", "y", "y", "y", "x", "x", "x", "a", "a"))
   rownames(df) <- tree$tip.label
   df2 <- as.data.frame(matrix(rnorm(39), ncol=3))
   rownames(df2) <- tree$tip.label
   colnames(df2) <- LETTERS[1:3]
   
   
   p1 <- gheatmap(circ, df, offset=.8, width=.2,
                  colnames_angle=95, colnames_offset_y = .25) +
       scale_fill_viridis_d(option="D", name="discrete\nvalue")
   
   
   library(ggnewscale)
   p2 <- p1 + new_scale_fill()
   gheatmap(p2, df2, offset=15, width=.3,
            colnames_angle=90, colnames_offset_y = .25) +
       scale_fill_viridis_c(option="A", name="continuous\nvalue")
   

1. my script of get_legend and plot_grid

   pp <- gheatmap(p2, df2, offset=15, width=.3, colnames_angle=90, colnames_offset_y = .25) + scale_fill_viridis_c(option="A", name="continuous\nvalue")+ theme(legend.position = "none")

   leg1 <- get_legend(p1)

   leg2 <- get_legend(gheatmap(circ, df2, offset=15, width=.3, colnames_angle=90, colnames_offset_y = .25) + scale_fill_viridis_c(option="A", name="continuous\nvalue"))

   plot_grid(pp,leg1,leg2,ncol=3)+theme(plot.background = element_rect(fill="grey"))

Answer 1

[Kevin Blighe]

Hey,

You can do this via standard ggplot2 functions:

gheatmap(p2, df2, offset=15, width=.3, colnames_angle=90, colnames_offset_y = .25) +

  scale_fill_viridis_c(option="A", name="continuous\nvalue") +

  theme(legend.position = 'bottom',
    legend.background = element_rect(),
    legend.key = element_blank(), # removes the border
    legend.key.size = unit(0.8, 'cm'), # sets overall area/size of the legend
    legend.text = element_text(size = 12), # text size
    title = element_text(size = 12))

So, if you want to make any further modifications, just search the WWW for ggplot2 general functionality.

Kevin

[YiweiZhu]

Thank you, Kevin! You do me a favor! I think it is moving legends to the bottom that changes legend arrangement. Quite a smart idea!

[YiweiZhu]

I just find legend.box parameter in the theme() function. That is exactly what I am searching for.