guide_colbar title property adjustment

[Breeze-Hu]

Dear Teun van den Brand,

Can guide_colbar add title.position and title.hjust parameters to adjust the title position of the colorbar like guide_colorbar in ggplot?

The following code adjusts the position of the colorbar, the position of the colorbar header (top and hjust), but does not set the out-of-range triangle shape:

library(tidyverse)
library(legendry)
library(terra)

m <- matrix(1:25, nrow=5, ncol=5)
rm <- rast(m)

# from a "xyz" data.frame
data <- as.data.frame(rm, xy=TRUE)
bwr_colors <- c("blue", "white", "red")

ggplot(data = data,aes(x = x,y = y,fill = lyr.1)) +
  geom_tile() + 
  scale_fill_gradientn(
    colors = bwr_colors, 
    na.value = NA,
    limits = c(5, 20), oob = scales::oob_squish,
    guide = guide_colorbar(#shape = "triangle",
                         title.position = "top",
                         title.hjust = 0.5)) +
  theme_bw()+
  theme(
    legend.position = "bottom",             
    legend.key.width = unit(2, "cm"),       
    legend.key.height = unit(0.4, "cm"))

It's more elegant to use guide_colbar when setting the triangle shape, but it doesn't seem to be possible to set the title position of the colorbar:

ggplot(data = data,aes(x = x,y = y,fill = lyr.1)) +
  geom_tile() + 
  scale_fill_gradientn(
    colors = bwr_colors, 
    na.value = NA,
    limits = c(5, 20), oob = scales::oob_squish,
    guide = guide_colbar(shape = "triangle")
                         # title.position = "top",
                         # title.hjust = 0.5)
  ) +
  theme_bw()+
  theme(
    legend.position = "bottom",             
    legend.key.width = unit(2, "cm"),       
    legend.key.height = unit(0.4, "cm"))     
)

If settings similar to the above are made, an error is prompted:

`Error in guide_colbar(shape = "triangle", title.position = "top", title.hjust = 0.5) : 
  unused arguments (title.position = "top", title.hjust = 0.5)'

Best regards
Hu

[teunbrand]

Hi Hu, thank you for the report!

At the risk of sounding slightly rude: no, absolutely not.

The reason is that ggplot2 has removed these arguments and they only still work because of a backward compatibility mechanism. The legendry package is not beholden to ggplot2's backward compatibility, so it will not use the old deprecated arguments.

The "proper" way of setting such customisations is via the guide_colourbar(theme) argument (see blog), and this works the same way in legendry. You could use theme_guide() to be slightly more terse. I could add an example of this, but it really isn't any different than ggplot2.

library(tidyverse)
library(legendry)
library(terra)

m <- matrix(1:25, nrow=5, ncol=5)
rm <- rast(m)

# from a "xyz" data.frame
data <- as.data.frame(rm, xy=TRUE)
bwr_colors <- c("blue", "white", "red")

ggplot(data = data,aes(x = x,y = y,fill = lyr.1)) +
  geom_tile() + 
  scale_fill_gradientn(
    colors = bwr_colors, 
    na.value = NA,
    limits = c(5, 20), oob = scales::oob_squish,
    guide = guide_colbar(
      theme = theme_guide(
        title.position = "top",
        title = element_text(hjust = 0.5)
      )
    )) +
  theme_bw()+
  theme(
    legend.position = "bottom",             
    legend.key.width = unit(2, "cm"),       
    legend.key.height = unit(0.4, "cm")
  )

^{Created on 2024-12-16 with reprex v2.1.1}

[Breeze-Hu]

Perfect! Thank you for your detailed reply. I read what you mentioned carefully and this does work well to unify the various attribute contents of the guide using the theme framework!
Thanks for contributing to the ggplot ecosystem! Packages such as legendry and ggh4x make plotting much more accessible and convenient!

[Breeze-Hu]

Sorry to bother you again.
is there something problem with the height and width adjustment of the colorbar in the theme_guide function provided by legendry?
Using key.width and key.height seems to have no effect. But it is valid to use theme instead of theme_guide .

See details:
stackoverflow-question

[teunbrand]

You're right this seems like a bug. I'm tracking it in #41.