是否可以通过ggrepel避免轴标签重叠？

Question

我正在用 ggplot2 绘制热图。 y 轴上的几个刻度需要标记。然而，它们中的一些太接近并且重叠。我知道 ggrepel 可以分隔文本标签，但目前我还没有解决我的问题。

我的代码如下。欢迎任何建议。谢谢。

代码：

df <- data.frame()

for (i in 1:50){
  tmp_df <- data.frame(cell=paste0("cell", i), 
                       gene=paste0("gene", 1:100), exp = rnorm(100), ident = i %% 5)
  df<-rbind(df, tmp_df)
}

labelRow=rep("", 100)
for (i in c(2, 5, 7, 11, 19, 23)){
  labelRow[i] <- paste0("gene", i)
}

library(ggplot2)
heatmap <- ggplot(data = df, mapping = aes(x = cell, y = gene, fill = exp)) +
  geom_tile() + 
  scale_fill_gradient2(name = "Expression") + 
  scale_y_discrete(position = "right", labels = labelRow) +
  facet_grid(facets = ~ident,
             drop = TRUE,
             space = "free",
             scales = "free", switch = "x") +
  scale_x_discrete(expand = c(0, 0), drop = TRUE) +
  theme(axis.line = element_blank(),
        axis.ticks = element_blank(),
        axis.title.y = element_blank(),
        axis.text.y = element_text(),
        axis.title.x = element_blank(),
        axis.text.x = element_blank(),
        strip.text.x = element_text(angle = -90))

heatmap

Answer 1

对于这类问题，我更喜欢将轴绘制为单独的图，然后合并。这需要一些摆弄，但可以让您绘制几乎任何您想要的轴。

在我的解决方案中，我使用了来自 cowplot 包的函数 get_legend()、align_plots() 和 plot_grid()。免责声明：我是包作者。

library(ggplot2)
library(cowplot); theme_set(theme_gray()) # undo cowplot theme setting
library(ggrepel)

df<-data.frame()
for (i in 1:50){
  tmp_df <- data.frame(cell=paste0("cell", i), 
                       gene=paste0("gene", 1:100), exp=rnorm(100), ident=i%%5)
  df<-rbind(df, tmp_df)
}


labelRow <- rep("", 100)
genes <- c(2, 5, 7, 11, 19, 23)
labelRow[genes] <- paste0("gene ", genes)

# make the heatmap plot
heatmap <- ggplot(data = df, mapping = aes(x = cell,y = gene, fill = exp)) +
  geom_tile() + 
  scale_fill_gradient2(name = "Expression") + 
  scale_x_discrete(expand = c(0, 0), drop = TRUE) + 
  facet_grid(facets = ~ident,
             drop = TRUE,
             space = "free",
             scales = "free", switch = "x") + 
  theme(axis.line = element_blank(),
        axis.title = element_blank(),
        axis.text = element_blank(),
        axis.ticks = element_blank(),
        strip.text.x = element_text(angle = -90),
        legend.justification = "left",
        plot.margin = margin(5.5, 0, 5.5, 5.5, "pt"))

# make the axis plot
axis <- ggplot(data.frame(y = 1:100,
                          gene = labelRow),
               aes(x = 0, y = y, label = gene)) +
  geom_text_repel(min.segment.length = grid::unit(0, "pt"),
                 color = "grey30",  ## ggplot2 theme_grey() axis text
                 size = 0.8*11/.pt  ## ggplot2 theme_grey() axis text
                 ) +
  scale_x_continuous(limits = c(0, 1), expand = c(0, 0),
                     breaks = NULL, labels = NULL, name = NULL) +
  scale_y_continuous(limits = c(0.5, 100.5), expand = c(0, 0),
                     breaks = NULL, labels = NULL, name = NULL) +
  theme(panel.background = element_blank(),
        plot.margin = margin(0, 0, 0, 0, "pt"))

# align and combine
aligned <- align_plots(heatmap + theme(legend.position = "none"), axis, align = "h", axis = "tb")
aligned <- append(aligned, list(get_legend(heatmap)))
plot_grid(plotlist = aligned, nrow = 1, rel_widths = c(5, .5, .7))