How to quantify heat maps?

Question

I have a heat map which has a gradient from green to red and the values range from -2 to 2.

Now I want to give a value to each block of the heat map, is there any way we can do it?

Welcome to SO! Your question is unclear, please read and edit your question according to: [How to make a great R reproducible example?](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) — pogibas, Sep 05 '18 at 18:51
`Ggplot2`'s `geom_tile()` could be helpful. However to have more help listen to @PoGibas — s__, Sep 05 '18 at 20:47
Possible duplicate of [heatmap with values (ggplot2)](https://stackoverflow.com/questions/14290364/heatmap-with-values-ggplot2) — Artem, Sep 24 '18 at 22:15

score 0 · Answer 1 · answered Sep 24 '18 at 22:12

Please see below the approach using tidyverse package. dat is transformed to dat2 from wide format into narrow. Then geom_tile is plotted:

library(tidyverse)

# simulation
dat <- matrix(runif(81, -2, 2), ncol = 9)

## reshape data (tidy/tall form)
dat2 <- dat %>%
  tbl_df() %>%
  rownames_to_column("Var1") %>%
  gather(Var2, value, -Var1) %>%
  mutate(
    Var1 = factor(Var1, levels=1:10),
    Var2 = factor(gsub("V", "", Var2), levels=1:10))

## plot data
ggplot(dat2, aes(Var1, Var2)) +
  geom_tile(aes(fill = value)) + 
  geom_text(aes(label = round(value, 1))) +
  scale_fill_gradient(low = "green", high = "red")

Output:

How to quantify heat maps?

1 Answers1