小编use*_*031的帖子

我正在尝试创建一个热图，显示驱动每个单元格中颜色的值。如果一个单元格因为有 5 个观测值而呈深蓝色，我想看到该单元格中的数字 5。

（目的是建立一个信用评级迁移矩阵，其中一个轴是今年的信用评级，另一个轴是去年的信用评级。输入是一个数据框，其中每一行是一个公司的一个观察值，即该公司今年的信用评级，以及去年的信用评级。该矩阵显示了哪些公司在两年内具有稳定的信用评级，哪些公司被授予较低的评级，哪些公司的评级提高了）。

这是数据和代码

require(ggplot2)

# Create a dataframe mm where each row is one observation for one company, 
# the company's credit rating this year, and it credit rating last year.  A company ID is 
# provided.  


mm<-data.frame(
    CompamyID = c(1:14),
    CurrentYear =c("Aaa","Aa","B","Baa","C","Aaa","Aa","B","Baa","C","Aa","B","Baa","C"),
    PreviousYear=c("Aaa","Aa","B","Baa","Aa","B","Baa","C","C","Aaa","Aa","B","Baa","C"),
    Count=rep(1,14)
)

# Create heatmap and show the number of observations in each cell.  
# I have used label= # sum() for illustration but it is wrong.  

ggplot(data=mm, aes(x = mm$CurrentYear, y=mm$PreviousYear)) + …