Map cell colors to data values in kableExtra to create a heatmap table

Question

I have a table below and would like to apply ROW-level heat maps.

(1) Any idea how? Right now the heat map is the same for both values in the single row below.

(2) Is there a way to make the header for the group column NOT be angled 90 degrees? Right now all headers are angled but for the group column it be better without angle=90.

here is the rmd file.

---
title: "Untitled"
output: pdf_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)


library(dplyr)
library(kableExtra)
#d = data.frame(group= c("A","b"),cat1=c(2,50),cat2=c(100,2))
d = data.frame(group= c("A"),cat1=c(2),cat2=c(NA))

d = d %>%
    mutate_if(is.numeric, function(x) {
  cell_spec(x, "latex", bold = F, background = spec_color(x,option="C", begin=.5, end = 0.99))
}) 

```



```{r table , echo= FALSE, comment = FALSE, message= FALSE, warning = FALSE, fig.height=3, fig.width = 8} 

kable(
      d, format ="latex",
      caption = "",
      booktabs = T, 
      longtable = T,
      escape = F ,
      align = "c"
      ) %>% kable_styling(latex_options = c(
        "striped", 
        "repeat_header"
        )
       )%>% row_spec( 0,angle = 90)


```

Note: Ideally it'd be good to have this done with the kableExtra functionality so they color schemes match exactley to other kableExtra tables.

Answer 1

I'm actually not sure how to get the desired color mapping from spec_color. As an alternative, in the code below I've generated the color mapping using the colorRamp function and a palette-generating function, which can be adjusted as desired. The code also deals with missing values by coloring them light gray.

---
output: pdf_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(viridis)
library(dplyr)
library(kableExtra)

set.seed(2)
d = data_frame(group = sample(LETTERS[1:5], 10, replace=TRUE), cat1=runif(10, 0, 100), cat2=runif(10, 0, 100))
d[5,2] = NA

max.val = max(d[ , sapply(d, is.numeric)], na.rm=TRUE)

#pal.fnc = colorRamp(viridis_pal(option="C")(2))
pal.fnc = colorRamp(c("red", "yellow", "green"))

d = d %>%
    mutate_if(is.numeric, function(x) {
  cell_spec(round(x,1), "latex", bold = F, color=grey(.3),
            background = rgb(pal.fnc(x/max.val) %>% replace(., is.na(.), 200), maxColorValue=255))
}) 

```

```{r table , echo= FALSE, comment = FALSE, message= FALSE, warning = FALSE, fig.height=3, fig.width = 8} 
kable(
      d, format ="latex",
      linesep="",
      caption = "",
      booktabs = T, 
      longtable = T,
      escape = F ,
      align = "c"
      ) %>% kable_styling(latex_options = c(
        "striped", 
        "repeat_header"
        )
       )
```