How to remove Y Axis Titles and replace them with Legend Titles-CodePudding

I just started R programming 2 weeks ago and i have a case study plot with 1 x axis and 2 y axis... I tried everything i can for 48 hours to replace Title with Legend... And i couldn't figure out what's the issue, Hopefully i can get help input from you guys.

PLOT:

ggplot(libya_covid, aes(x=date))  
  
  geom_line( aes(y=new_tests), size=2, color='blue')   
  geom_line( aes(y=new_cases / 1), size=2, color='darkorange')  
  
  xlab("Date") 
  
  scale_y_continuous(
    
    # Features of the first axis
    name = "New Tests",
    
    # Add a second axis and specify its features
    sec.axis = sec_axis(~.*1, name= "New Cases")
  )   
  
  theme_bw()  
  
  theme(
    axis.title.y = element_text(color = 'blue', size=13),
    axis.title.y.right = element_text(color = 'darkorange', size=13)
  )  
  
  ggtitle("New Tests Versus New Cases Analysis")

Now I just Want To Remove Y Titles from Right & Left and ADD Simple Legend On Top Left

Thanks in Advance.

CodePudding user response：

In ggplot2 legends reflect aesthetics or scales. This said, if you want to have a legend you have to map on aesthetics.

To get a legend depicting the different colored lines you could map a constant value on the color aesthetic and then assign your desired colors to these constants using scale_color_manual.

To get rid of the labels remove the name=s from scale_y_continious and using labs set y=NULL which means remove the y axis title. Finally, you could position the legend via theme options legend.position and legend.justification:

library(ggplot2)

#### Use economics dataset as example data
libya_covid <- ggplot2::economics
names(libya_covid)[4:5] <- c("new_tests", "new_cases")
####

ggplot(libya_covid, aes(x=date))  
  geom_line( aes(y=new_tests, color='New Tests'), size=2)   
  geom_line( aes(y=new_cases / 1, color='New Cases'), size=2)  
  labs(x = "Date", y = NULL, color = NULL, title = "New Tests Versus New Cases Analysis")  
  scale_y_continuous(
    sec.axis = sec_axis(~.*1)
  )   
  scale_color_manual(values = c("New Tests" ='blue', "New Cases" ='darkorange'))  
  theme_bw()  
  theme(
    axis.title.y = element_text(color = 'blue', size=13),
    axis.title.y.right = element_text(color = 'darkorange', size=13),
    legend.position = c(0.05, .95),
    legend.justification = c(0.05, .95)
  )