ggplot作图叠加背景/渐变色背景

ggplot作图之前我们使用过geom_rect函数为图形增加背景，但是仅仅限于图形内部，那么如何对整个ggplot背景进行改色呢？我们使用一个简单的火山图示例图，首先做一个火山图：

setwd("E:/生物信息学/ggplot火山图")
df <- read.csv("DEG.csv",header = T)

默认无修饰背景的图如下：

p <- ggplot(df, aes(x=avg_log2FC, y=-log10(p_val_adj))) +
  geom_hline(aes(yintercept=1.3), color = "#999999", linetype="dashed", size=1)+
  geom_vline(aes(xintercept= -0.25), color = "#999999", linetype="dashed", size=1)+ 
  geom_vline(aes(xintercept= 0.25), color = "#999999", linetype="dashed", size=1)+
  geom_point(size=3, shape=21, color="black", fill="grey") + 
  theme_bw()+
  theme(panel.grid.major=element_blank(),
        panel.grid.minor=element_blank(),
        panel.border = element_blank(),
        axis.line = element_line(colour = "black",size = 0.5),
        axis.title =element_text(size = 14, color = "black"),
        axis.text =element_text(size = 12, color = "black"))+
  labs(x = "Log2 fold change",y = "-Log10(P-value)", title = "") +
  annotate("text", label = "Down-regulated DEGs\nin treatment", 
           x = -2.2, y = 250, size=5)+
  annotate("text", label = "Up-regulated DEGs\nin treatment", 
           x = 2.2, y = 250, size= 5)

image.png

去掉theme_bw()，增加ggthemes::theme_solarized()，即更改主题，就可以得到灰黄色的背景色了。这个图还是很有质感的，可以应用到其他图形中。

library(ggplot2)
ggplot(df, aes(x=avg_log2FC, y=-log10(p_val_adj))) +
  ggthemes::theme_solarized()+
  geom_hline(aes(yintercept=1.3), color = "#999999", linetype="dashed", size=1)+
  geom_vline(aes(xintercept= -0.25), color = "#999999", linetype="dashed", size=1)+ 
  geom_vline(aes(xintercept= 0.25), color = "#999999", linetype="dashed", size=1)+
  geom_point(size=3, shape=21, color="black", fill="grey") + 
  theme(panel.grid.major=element_blank(),
        panel.grid.minor=element_blank(),
        panel.border = element_blank(),
        axis.line = element_line(colour = "black",size = 0.5),
        axis.title =element_text(size = 14, color = "black"),
        axis.text =element_text(size = 12, color = "black"))+
  labs(x = "Log2 fold change",y = "-Log10(P-value)", title = "") +
  annotate("text", label = "Down-regulated DEGs\nin treatment", 
           x = -2.2, y = 250, size=5)+
  annotate("text", label = "Up-regulated DEGs\nin treatment", 
           x = 2.2, y = 250, size= 5)

image.png

当然了，更加高级的方式则是使用渐变色：

ggplot(df, aes(x=avg_log2FC, y=-log10(p_val_adj))) +
  geom_hline(aes(yintercept=1.3), color = "#999999", linetype="dashed", size=1)+
  geom_vline(aes(xintercept= -0.25), color = "#999999", linetype="dashed", size=1)+ 
  geom_vline(aes(xintercept= 0.25), color = "#999999", linetype="dashed", size=1)+
  geom_point(size=3, shape=21, color="black", fill="grey") + 
  theme_bw()+
  theme(panel.grid.major=element_blank(),
        panel.grid.minor=element_blank(),
        panel.border = element_blank(),
        axis.line = element_line(colour = "black",size = 0.5),
        axis.title =element_text(size = 14, color = "black"),
        axis.text =element_text(size = 12, color = "black"))+
  labs(x = "Log2 fold change",y = "-Log10(P-value)", title = "") +
  annotate("text", label = "Down-regulated DEGs\nin treatment", 
           x = -2.2, y = 250, size=5)+
  annotate("text", label = "Up-regulated DEGs\nin treatment", 
           x = 2.2, y = 250, size= 5)


library(RColorBrewer)
library(grid)
color <- colorRampPalette(brewer.pal(11,"RdBu"))(15)

grid.raster(scales::alpha(color, 0.3), 
            width = unit(1, "npc"), 
            height = unit(1,"npc"),
            interpolate = T)

image.png

之前在一篇文章中见到过这种做法，找不到原文了，如果找到了再补上吧。这种新奇的背景应用到柱状图、小提琴图、折线图等等图形修饰中，都会有更好的效果！

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