i have the following data frame in R

A tibble: 24 × 4
   answers  Year Categories Satisfaction
   <chr>   <dbl> <chr>             <dbl>
 1 A        2019 Football           46.7
 2 A        2019 Basket             20.7
 3 A        2019 Volley             36.5
 4 A        2020 Football           43.7
 5 A        2020 Basket             21  
 6 A        2020 Volley             31.2
 7 A        2022 Football           49  
 8 A        2022 Basket             17.9
 9 A        2022 Volley             34.2
10 A        2023 Football           33.8

which its structure in R is the following:

df = structure(list(answers = c("A", "A", "A", "A", "A", "A", "A", 
"A", "A", "A", "A", "A", "B", "B", "B", "B", "B", "B", "B", "B", 
"B", "B", "B", "B"), Year = c(2019, 2019, 2019, 2020, 2020, 2020, 
2022, 2022, 2022, 2023, 2023, 2023, 2019, 2019, 2019, 2020, 2020, 
2020, 2022, 2022, 2022, 2023, 2023, 2023), Categories = c("Football", 
"Basket", "Volley", "Football", "Basket", "Volley", "Football", 
"Basket", "Volley", "Football", "Basket", "Volley", "Tennis", 
"Hockey", "Other", "Tennis", "Hockey", "Other", "Tennis", "Hockey", 
"Other", "Tennis", "Hockey", "Other"), Satisfaction = c(46.7, 
20.7, 36.5, 43.7, 21, 31.2, 49, 17.9, 34.2, 33.8, 30.1, 33.2, 
68.7, 68.7, 68.7, 69.7, 70.2, 70.2, 66.8, 72.7, 72.7, 76.1, 75.4, 
75.4)), row.names = c(NA, -24L), class = c("tbl_df", "tbl", "data.frame"
))

i have grouped the plot using ggplot2 as follows and as the picture shows. But I want to change the colours of the background themes.

If it is the A group the theme to be green and if is group B to be red. And then to display from right to left the red and then the green (ie at the left the red one B and at the right the green A). How can i do it in R ?

P2 = ggplot(df, aes(x = Year, y = Satisfaction, color = factor(Categories), group = Categories)) +
  geom_line(aes(color = ifelse(answers == "Unfavorable", "darkred", "forestgreen"))) +
  geom_point(size = 2) +
  facet_grid(Categories ~ answers, scales = "free_y") +
  theme_minimal() +
  labs(
    x = "Year",
    y = "Satisfaction",
    color = "Categories") +
  # theme(axis.text.x = element_text(angle = 45, hjust = 1))+
  theme(axis.text.x = element_text(angle = 45, hjust = 1),
        strip.background = element_rect(fill = "lightgrey"), # Add background color to facet labels
        strip.text = element_text(size = 12, face = "bold"), # Enhance facet label text
        panel.spacing = unit(1, "lines")) + # Increase spacing between facets
  geom_text(aes(label = paste(Satisfaction,"%") ), nudge_x = 0.1,color="black")+
  theme(legend.position = "none")
P2

To change the facets' order use the standard trick of coercing the faceting variable to factor with the levels in the order you want.
And to have a different background color, the fast hack is to add another layer, geom_rect, going from -Inf to Inf. Play with the alpha value at will.

First I define a new, custom theme

theme_so_q78904457 <- function(){ 
  theme_minimal(base_size = 10) %+replace%    #
    theme(
      axis.text.x = element_text(angle = 45, hjust = 1),
      strip.background = element_rect(fill = "lightgrey"), # Add background color to facet labels
      strip.text = element_text(size = 12, face = "bold"), # Enhance facet label text
      panel.spacing = unit(1, "lines"),                    # Increase spacing between facets
      legend.position = "none"
    )
}

^{Created on 2024-08-23 with reprex v2.1.0}

---

Plot code

Note that the fill variable length must be the same as the number of rows in data. That's why I repeat 12 times each value with rep(12L).

library(ggplot2)

df$answers <- factor(df$answers, levels = sort(unique(df$answers), decreasing = TRUE))

P2 <- ggplot(df, aes(x = Year, y = Satisfaction, color = factor(Categories), group = Categories)) +
  geom_line(aes(color = ifelse(answers == "Unfavorable", "darkred", "forestgreen"))) +
  geom_point(size = 2) +
  geom_text(aes(label = paste(Satisfaction,"%") ), nudge_x = 0.1,color="black")+
  facet_grid(Categories ~ answers, scales = "free_y") +
  labs(
    x = "Year",
    y = "Satisfaction",
    color = "Categories"
  ) +
  theme_so_q78904457()

P2 +
  geom_rect(
    fill = c(A = "green", B = "red") |> rep(each = 12L),
    color = NA,  # removes the rectangles' border
    xmin = -Inf, xmax = Inf, ymin = -Inf, ymax = Inf,
    alpha = 0.05
  )

^{Created on 2024-08-23 with reprex v2.1.0}

---

Edit

To group the panels by color, add the following code prior to plotting. Once again, the trick is to set the factor levels by the wanted order.

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

df %>%
  select(answers, Categories) %>%
  unique() %>%
  arrange(answers) %>%
  pull(Categories) -> cat_levels

df$Categories <- factor(df$Categories, levels = cat_levels)

^{Created on 2024-08-23 with reprex v2.1.0}