为直方图和密度图添加文本标签

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平时在阅读文献时经常会看到一些加标签的图，比如下面这张：

那如何来方便地绘制呢？下面就介绍下如何使用R包ggpubr来绘制带有文本标签的直方图和密度图。
下面将使用ggpubr包中的gene_citation数据集，它包含通过使用两个关键词（ i）基因名称+ b细胞分化和 ii）基因名称+浆细胞分化）评估PubMed中摘要和注释筛选的66个基因的平均引用指数。每个基因的引文数作为使用两个关键词获得的平均引文数，仅保留平均引文数>=3的基因。
绘制基因引文索引的条形图：

library(ggpubr)
# 加载数据
data(gene_citation)
head(gene_citation)

##      gene citation_index
## 2   CASP3           68.0
## 4    CDK6           10.5
## 7   CCND2           10.0
## 8     SCD            8.5
## 10 SLAMF6            4.5
## 11 BCL2L1           56.5

ggbarplot(gene_citation, x = "gene", y = "citation_index",
          fill = "lightgray", 
          xlab = "Gene name", ylab = "Citation index",
          sort.val = "desc", # 按降序排序
          top = 20,          # 选择前20个基因
          x.text.angle = 45  # x轴标签旋转45度
          )

上图显示了一些已知的与浆细胞分化有关的关键基因。

# 一些关键基因
key.gns <- c("MYC", "PRDM1", "CD69", "IRF4", "CASP3",
             "BCL2L1", "MYB",  "BACH2", "BIM1",  "PTEN",
             "KRAS", "FOXP1", "IGF1R", "KLF4", "CDK6", "CCND2",
             "IGF1", "TNFAIP3", "SMAD3", "SMAD7",
             "BMPR2", "RB1", "IGF2R", "ARNT")
        
# 绘制带标签的直方图
gghistogram(gene_citation, x = "citation_index", y = "..count..",
            xlab = "Number of citation",
            ylab = "Number of genes",
            binwidth = 5, 
            fill = "lightgray", color = "black",
            label = "gene", label.select = key.gns, repel = TRUE,
            font.label = list(color= "citation_index"),
            xticks.by = 20, # x轴刻度步长值
            gradient.cols = c("blue", "red"),
            legend = c(0.7, 0.6),                                 
            legend.title = ""       # 隐藏图例标题
            )

# 带标签的密度图
ggdensity(gene_citation, x = "citation_index", y = "..count..",
            xlab = "Number of citation",
            ylab = "Number of genes",
            fill = "lightgray", color = "black",
            label = "gene", label.select = key.gns, repel = TRUE,
            font.label = list(color= "citation_index"),
            xticks.by = 20, # x轴刻度步长值
            gradient.cols = c("blue", "red"),
            legend = c(0.7, 0.6),                                 
            legend.title = ""       # 隐藏图例标题
            )

参考

• Add Text Labels to Histogram and Density Plots