Dropping item from ggplot legend while keeping asthetics of those values

Question

I want to display both an annual value (school hours) and its cumulative (total school hours) in the same graph. This works, so now I want to tidy-up the legend a little bit. I want to drop the three groups associated with the cumulative values and only report a custom label for each state I use. Thus, the legend should only read "NW, G8", "NW, G9", and "CA", next to the colour they are associated with.

I have found other solutions to this problem which no longer seem to work with the current ggplot version (at least I believe this to be a version-issue, maybe I made another mistake):

https://community.rstudio.com/t/how-keep-aesthetic-mapping-but-remove-a-specific-item-from-legend-with-ggplot/52818/3 -> trying to replicate the solution with the provided code results in a gray barplot "c" and not a blue bar plot for me.

Remove legend entries for some factors levels -> again, similar solution, but if I update my scale_color_manual to the following alternative, I again have gray lines for my cumulative values

  scale_color_manual(breaks = c("hours_nw_G8", "hours_nw_G9", "hours_ca"),
                    values = c("#073B4C", "#118AB2", "#FFD166", "#073B4C", "#118AB2", "#FFD166")) +

Code:

require(tidyverse)

## school hours: comparison of US state (CA) and DE State (NW) 
df_hours <- data.frame(year=c(1:13),
                       hours_nw_G8=c(21.5,22.5,25.5,26.5,31.5,31.5,32.5,32.5,33.5,34,34,34,NA),
                       hours_nw_G9=c(21.5,22.5,25.5,26.5,28,29,30,30,31,31,31.5,29.5,29.5),
                       hours_ca=c(840,840,840,900,900,900,900,900,1080,1080,1080,1080,NA)
                       )
df_hours$hours_nw_G8 <- df_hours$hours_nw_G8 * 38 * 0.75 # scaling by #weeks and accounting for German school hour
df_hours$hours_nw_G9 <- df_hours$hours_nw_G9 * 38 * 0.75

# cumulate 
df_hours$c_hours_nw_G8 <- cumsum(df_hours$hours_nw_G8) / 8 # cummulate and divide by scaling factor 
df_hours$c_hours_nw_G9 <- cumsum(df_hours$hours_nw_G9) / 8
df_hours$c_hours_ca <- cumsum(df_hours$hours_ca) / 8

# reshape & dummy for cumulative 
df_hours <- gather(df_hours, state, hours, hours_nw_G8:c_hours_ca, factor_key=TRUE)
df_hours$cu <- c(rep("annual",13*3),rep("cumulative",13*3))


# Figure 
ggplot(df_hours, aes(x=year)) +
  geom_line(aes(y=hours, color=state, linetype=cu), linewidth = 1) +
  scale_y_continuous(limits = c(0,1500), expand = c(0,0),
                     breaks = c(0,250,500,750,1000,1250,1500),
                     name="Hours (annual)",
                     sec.axis = sec_axis(~ .*8, name = "Hours (cummulative)",
                                         breaks = c(0,2000,4000,6000,8000,10000,12000))
                     ) +
  scale_x_continuous(limits = c(0.5,13.5), expand = c(0,0), breaks = c(1:13)) +
  labs(x="School Year", y="Hours") +
  theme_tufte() +
  scale_color_manual(values = c("#073B4C", "#118AB2", "#FFD166", "#073B4C", "#118AB2", "#FFD166")) +
  theme(axis.line = element_line(linewidth = 0.75), text = element_text(size = 10, color = "black"),
        legend.position = c(.3, .9), legend.title = element_blank()) + 
  guides(linetype = F)

Answer 1

One solution could be using some stringr function to modify the strings:

library(ggthemes)
library(tidyverse)

df_hours %>% 
  mutate(state_label = str_remove(state, "c_hours_|hours_"),
         state_label = str_to_upper(state_label),
         state_label = str_replace(state_label, "_", ", ")) %>% 
  ggplot(aes(x=year)) +
  geom_line(aes(y=hours, color=state_label, linetype=cu), linewidth = 1) +
  scale_y_continuous(limits = c(0,1500), expand = c(0,0),
                     breaks = c(0,250,500,750,1000,1250,1500),
                     name="Hours (annual)",
                     sec.axis = sec_axis(~ .*8, name = "Hours (cummulative)",
                                         breaks = c(0,2000,4000,6000,8000,10000,12000))
  ) +
  scale_x_continuous(limits = c(0.5,13.5), expand = c(0,0), breaks = c(1:13)) +
  labs(x="School Year", y="Hours") +
  theme_tufte() +
  scale_color_manual(values = c("#073B4C", "#118AB2", "#FFD166", "#073B4C", "#118AB2", "#FFD166")) +
  theme(axis.line = element_line(0.75), text = element_text(size = 10, color = "black"),
        legend.position = c(.3, .9), legend.title = element_blank()) + 
  guides(linetype = F)