different titles for each element after using facet

After setting ncol = 1 in the facet_wrap() function, I'm trying to use ggtitle() function inside the facet_wrap() function to set a different title for each graph created (there are only two of them).

ggplot(df, aes(x, y))  
  geom_point()  
  facet_wrap(~ var, ncol = 1)  
  ggtitle(function(x) paste("Title for", df$title[df$var == x]))

I'm trying to use the value of the "title" column of the dataframe, where the value of the "var" column matches the value of the current plot's var.

But I get this error:

Error in as.character(x$label) : 
  cannot coerce type 'closure' to vector of type 'character'

How can I set different titles for each graph in ggplot2 using the facet_wrap() function with ncol=1?

Thanks, Ido

CodePudding user response：

Here is something that might give you what you want. My comment above still stands, but this may be more what you are looking for.

library(ggplot2)
library(dplyr)

df <- mtcars %>% 
  mutate(strip_title = paste(cyl, "Cylinders"))

ggplot(df, aes(x = mpg, y = wt))  
  geom_point()  
  facet_wrap(~strip_title, ncol = 1)