我有 2 個資料框，如下所示：

df_hk_genes_pre = structure(list(ACTB = c(11.6704399, 12.458028, 11.200511, 12.3073524, 
12.066374, 12.064411, 12.1516557, 8.669943, 12.045182, 12.35896, 
11.3328069, 10.226411, 11.8971381, 12.0288182, 11.6919341, 12.0735249, 
11.8812387, 11.8266266, 11.5526943, 12.3936434), ATP5F1 = c(8.6677137, 
8.260138, 8.421619, 8.1465627, 8.956782, 8.792251, 8.6480966, 
8.700314, 8.850915, 8.446602, 8.7311666, 8.762719, 8.1397597, 
7.9228606, 8.909108, 8.8039817, 8.4693453, 8.5861887, 8.2678096, 
8.7482762)), row.names = c(NA, 20L), class = "data.frame")

df_hk_genes_post = structure(list(ACTB = c(11.7087918, 13.1847403, 8.767737, 12.2949669, 
12.399929, 12.130683, 9.816222, 10.700336, 11.862543, 12.479818, 
12.48152, 11.798277, 12.0932696, 11.014992, 12.3496682, 11.9810211, 
11.946094, 12.1517049, 11.6794028, 12.4895911), ATP5F1 = c(8.3731175, 
8.3995189, 8.871088, 8.4389342, 8.529104, 9.004405, 8.883721, 
8.70097, 8.24411, 8.393635, 8.76813, 8.756177, 8.4418168, 7.986864, 
8.4840108, 8.6523954, 8.5645576, 8.2452877, 8.2440872, 8.7155973
)), row.names = c(NA, 20L), class = "data.frame")

我使用以下代碼分別為每個生成直方圖網格：

setDT(df_hk_genes_post)
melt(df_hk_genes_post) %>% 
  ggplot(aes(x = value))   
  facet_wrap(~ variable, nrow = 2, scale = "free")  
  geom_histogram(
    fill="#69b3a2", color="#69b3a2", alpha=0.4, position="identity", bins=20
    )  
  scale_x_continuous(
    sec.axis = sec_axis(
      ~ . , name = "CPM of House-Keeping Genes Distribution", 
      breaks = NULL, labels = NULL
      )
    )

但現在我希望用不同的顏色在同一個網格上繪制兩者。是否可以使用相同的代碼段或應該采用不同的方法？

uj5u.com熱心網友回復：

您可以使用以下代碼。首先制作一個單獨的資料框，并使用額外的列指定哪個是 pre 哪個是 post。PrePost然后也生成一個刻面var的繪圖。

library(data.table)

## add column identifying pre or post: PrePost
## and rowbind together,
## make a factor from PrePost
df_hk_genes_pre$PrePost <- "pre"
df_hk_genes_post$PrePost <- "post"
df_hk_genes_all <- rbind(df_hk_genes_pre, df_hk_genes_post)
df_hk_genes_all$PrePost <- factor(df_hk_genes_all$PrePost)

## plot with facets in rows for "PrePost"
## and facets in columns for "variable"
setDT(df_hk_genes_all)
melt(df_hk_genes_all) %>% 
  ggplot(aes(x = value, fill = PrePost))                     ### fill col based on PrePost
  facet_grid(cols = vars(variable), rows = vars(PrePost))    ### PrePost in facet rows
  geom_histogram(
    bins=20
    , color= "grey"                                          ### visually distinct bars
  )  
  scale_x_continuous(
    sec.axis = sec_axis(
      ~ . , name = "CPM of House-Keeping Genes Distribution", 
      breaks = NULL, labels = NULL
    )
  )

這會產生以下圖表：

如果要更改填充顏色，可以添加類似于以下內容的行：

  scale_fill_manual(values= c("#69b3a2", "#25a3c9"))  

請讓我知道這是否是您的想法。

編輯 01

如果您想在同一個子圖上進行 pre 和 post，那么您可以將 position = "dodge"其用作引數geom_histogram()

setDT(df_hk_genes_all)
melt(df_hk_genes_all) %>% 
  ggplot(aes(x = value, fill = PrePost))                     ### fill col based on PrePost
  facet_grid(cols = vars(variable))    
  geom_histogram(
    bins=20
    , color= "grey",                                          ### visually distinct bars
    , position = "dodge"                                      ### dodging
  )  
  scale_x_continuous(
    sec.axis = sec_axis(
      ~ . , name = "CPM of House-Keeping Genes Distribution", 
      breaks = NULL, labels = NULL
    )
  )

...產生這個情節：

uj5u.com熱心網友回復：

同樣，如果您想展示更緊密的重疊，您可以在同一個圖上組合兩個變數級別

df_hk_genes_pre2 = reshape::melt(df_hk_genes_pre) %>% 
    mutate(status = "pre") 
    
df_hk_genes_post2 = reshape::melt(df_hk_genes_post) %>% 
    mutate(status = "post") 
    
bind_rows(df_hk_genes_pre2, df_hk_genes_post2) %>%
    mutate(status = factor(status, levels = c("pre", "post"))) %>% 
    ggplot(aes(x = value, fill = variable))  
    facet_wrap(~ status, nrow = 2, scale = "free")  
    geom_histogram(position = "identity", bins = 20, alpha = .4)   
    scale_fill_manual(values= c("#69b3a2", "black"))  
    scale_color_manual(values = c("#69b3a2", "black"))  
    scale_x_continuous(
        sec.axis = sec_axis(
            ~ . , name = "CPM of House-Keeping Genes Distribution", 
            breaks = NULL, labels = NULL
        )
    )

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