Change `ggplot` label color by conditions - r

Question

I have a question about changing color for geom_text & geom_label base on a condition.
Expected out put
Data label has color = blue for 2021, color = grey for 2020
Gap label is red when negative and green when positive
Data
data <- tibble(Factor = c("A", "B", "A", "B"),
Score = c(90, 85, 85, 90),
Year = c("2020", "2020", "2021", "2021"))
Data transform
df_2 = data %>%
pivot_wider(names_from = Year, names_prefix = "Year", values_from = Score) %>%
mutate(gap = Year2021 - Year2020) %>%
select(Factor, gap)
Plot
data %>%
left_join(df_2) %>%
ggplot(aes(x = Factor, y = Score, fill = Year)) +
geom_col(position='dodge') +
geom_text(aes(label=Score),
position=position_dodge(width = 0.9),
vjust=-0.40) +
geom_label(aes(y = 100, label = ifelse(Year == 2021, gap, NA_character_)), na.rm = TRUE) +
scale_y_continuous(limits = c(0,105))
theme_minimal()
Expected out put
85 & 90 = blue for 2021, 90 & 85 = grey for 2020
-5 = red and 5 = green

Answer 1

Second option would be to use a manual scale for the text and bar colors. For the labels we could use the ggnewscale package which allows for multiple scales for the same aesthetic. Doing so we could add a second fill scale:
library(ggplot2)
library(ggnewscale)
ggplot(dat, aes(x = Factor, y = Score, fill = Year)) +
geom_col(position = "dodge") +
geom_text(aes(label = Score, color = Year),
position = position_dodge(width = 0.9),
vjust = -0.40
) +
scale_color_manual(aesthetics = c("fill", "color"), values = c("2021" = "blue", "2020" = "grey")) +
ggnewscale::new_scale_fill() +
geom_label(aes(y = 100, label = ifelse(Year == 2021, gap, NA_character_), fill = gap > 0), na.rm = TRUE) +
scale_fill_manual(values = c("FALSE" = "red", "TRUE" = "green")) +
scale_y_continuous(limits = c(0, 105)) +
theme_minimal()
DATA
data <- data.frame(
Factor = c("A", "B", "A", "B"),
Score = c(90, 85, 85, 90),
Year = c("2020", "2020", "2021", "2021")
)
library(dplyr)
library(tidyr)
df_2 <- data %>%
pivot_wider(names_from = Year, names_prefix = "Year", values_from = Score) %>%
mutate(gap = Year2021 - Year2020) %>%
select(Factor, gap)
dat <- data %>%
left_join(df_2)

Answer 2

You can conditionally assign the colors to the aesthetics using case_when. You can use the following code:
library(tibble)
library(ggplot2)
library(dplyr)
library(tidyr)
data <- tibble(Factor = c("A", "B", "A", "B"),
Score = c(90, 85, 85, 90),
Year = c("2020", "2020", "2021", "2021"))
df_2 = data %>%
pivot_wider(names_from = Year, names_prefix = "Year", values_from = Score) %>%
mutate(gap = Year2021 - Year2020) %>%
select(Factor, gap)
df <- data %>% left_join(df_2)
#> Joining, by = "Factor"
ggplot(df, mapping = aes(x = Factor, y = Score, fill = Year)) +
geom_col(position='dodge') +
geom_text(df, mapping = aes(label=Score, color = Year),
color = case_when(
df$Score == 85 & df$Year == 2021 | df$Score == 90 & df$Year == 2021 ~ "blue",
df$Score == 85 & df$Year == 2020 | df$Score == 90 & df$Year == 2020 ~ "grey",
),
position=position_dodge(width = 0.9),
vjust=-0.40) +
geom_label(data = df, mapping = aes(y = 100, label = ifelse(Year == 2021, gap, NA_character_)),
fill = case_when(
df$gap == -5 ~ "red",
df$gap == 5 ~ "green"
), na.rm = TRUE) +
scale_y_continuous(limits = c(0,105)) +
theme_minimal()
Created on 2022-09-24 with reprex v2.0.2