I have been trying to minimize my use of Excel in favor of R, but am still stuck when it comes to display simple data cells as is often needed as the last step of an analysis. T
Your correlation matrix has several values greater than 1, which is not possible. But anyhow...
Try this one
library(reshape2)
dat <- melt(cor_matrix[-11, ])
library(ggplot2)
p <- ggplot(data = dat, aes(x = Var1, y = Var2)) +
geom_tile(aes(fill = value), colour = "white") +
geom_text(aes(label = sprintf("%1.2f",value)), vjust = 1) +
scale_fill_gradient(low = "white", high = "steelblue")
print(p)