r - ggplot 热图网格线格式 geom_tile 和 geom_rect

Question

几天来，我一直致力于创建热图，但无法使网格线的最终格式正常工作。请参阅下面的代码和附图。我想要做的是使用 geom_tile() 沿着热图的图块对齐网格线，以便每个图块以框方式填充网格内部。我能够使用 geom_raster() 对齐网格线，但 y 轴标签在瓷砖的顶部或底部打勾，但我需要它在中心打勾(参见红色突出显示)，我也无法让 geom_raster 换行瓷砖周围的白线边框，因此色块在我的原始数据集中看起来有点困惑。对格式代码的任何帮助将不胜感激。非常感谢!

#The data set in long format 


y<- c("A","A","A","A","B","B","B","B","B","C","C","C","D","D","D")
    x<- c("2020-03-01","2020-03-15","2020-03-18","2020-03-18","2020-03-01","2020-03-01","2020-03-01","2020-03-01","2020-03-05","2020-03-06","2020-03-05","2020-03-05","2020-03-20","2020-03-20","2020-03-21")
    v<-data.frame(y,x)

#approach 1 using geom_tile but gridline does not align with borders of the tiles 
    v%>%
      count(y,x,drop=FALSE)%>%
      arrange(n)%>%
      ggplot(aes(x=x,y=fct_reorder(y,n,sum)))+
      geom_tile(aes(fill=n),color="white", size=0.25)

我试过从 another post 运行类似的代码但我无法让它正常运行。我认为因为我的 x 变量是 y 变量的计数变量，所以不能格式化为因子变量以在 geom_rect() 中指定 xmin 和 xmax

#approach 2 using geom_raster but y-axis label can't tick at the center of tiles and there's no border around the tile to differentiate between tiles. 

v%>%
  count(y,x,drop=FALSE)%>%
  arrange(n)%>%
  ggplot()+
  geom_raster(aes(x=x,y=fct_reorder(y,n,sum),fill=n),hjust=0,vjust=0)

Answer 1

我认为保持刻度线和网格线在它们所在的位置是有意义的。为了仍然实现您正在寻找的内容，我建议您扩展数据以包含所有可能的组合，只需设置 na.value到中性填充颜色:

# all possible combinations
all <- v %>% expand(y, x)

# join with all, n will be NA for obs. in all that are not present in v
v = v %>% group_by_at(vars(y, x)) %>% 
    summarize(n = n()) %>% right_join(all)

ggplot(data = v, 
       aes(x=x, y=fct_reorder(y,n, function(x) sum(x, na.rm = T))))+ # note that you must account for the NA values now 
geom_tile(aes(fill=n), color="white",
        size=0.25) +
scale_fill_continuous(na.value = 'grey90') +
scale_x_discrete(expand = c(0,0)) +
scale_y_discrete(expand = c(0,0))