关于ggplot2：如何在r中的热图单元格中显示数字单元格值

How to show the numeric cell values in heat map cells in r

我正在尝试创建一个热图，以显示驱动每个单元格中颜色的值。如果一个单元格是深蓝色的，因为它有 5 个观察值，我想查看该单元格中的数字 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，公司\\'今年的信用评级和去年的信用评级。该矩阵显示哪些公司在两年内具有稳定的信用评级，哪些公司的评级较低，哪些公司的评级较高)。

这是数据和代码

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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)) +
geom_bin2d() +
geom_text(aes(fill = mm$Count, label = sum(mm$Count)))+
scale_x_discrete(limits =c("Aaa","Aa","A","Baa","Ba","B","Caa","Ca","C")) +
scale_y_discrete(limits=c("C","Ca","Caa","B","Ba","Baa","A","Aa","Aaa")) +
scale_fill_gradient2() +
theme(panel.grid.major = element_line( colour ="white", size = 0.5 ))+
theme(panel.grid.minor = element_line( colour ="black", linetype ="dashed", size = 0.5)) +
theme(panel.background = element_rect( colour ="black", fill ="white",size = 1.0 )) +
ggtitle("MIGRATION MATRIX USING geom_bin2d()") +
xlab("Current Year") +
ylab("Previous Year")

我会使用 stat_bin2d，所以 ggplot2 会在内部计算计数并以 ..count.. 的名称提供它们。

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ggplot(data=mm, aes(x = mm$CurrentYear, y=mm$PreviousYear)) +
geom_bin2d() +
stat_bin2d(geom="text", aes(label=..count..))+
scale_x_discrete(limits =c("Aaa","Aa","A","Baa","Ba","B","Caa","Ca","C")) +
scale_y_discrete(limits=c("C","Ca","Caa","B","Ba","Baa","A","Aa","Aaa")) +
scale_fill_gradient2() +
theme(panel.grid.major = element_line( colour ="white", size = 0.5 ))+
theme(panel.grid.minor = element_line( colour ="black", linetype ="dashed", size = 0.5)) +
theme(panel.background = element_rect( colour ="black", fill ="white",size = 1.0 )) +
ggtitle("MIGRATION MATRIX USING geom_bin2d()") +
xlab("Current Year") +
ylab("Previous Year")

希望对你有帮助。