Updating a theme to remove panel.grid.major.x

[llrs]

I am trying to suppress the panel.grid.major.x lines, I can do so if I use + but not if I update the theme using theme_update. The error mentions element_line but it happens with other types of element.

It might be related to #1880 and to the #1555

library("ggplot2")
theme_update(theme(panel.grid.major.x = element_blank()))
#> Error in (function (el, elname) : Element line must be a element_line object.
theme_update(theme(panel.grid.major.x = element_line(colour = "white")))
#> Error in (function (el, elname) : Element line must be a element_line object.
modified_theme <- theme_bw() +
  theme(panel.grid.major.x = element_blank())
theme_update(modified_theme)
#> Error in (function (el, elname) : Element line must be a element_line object.
modified_theme <- theme_bw() +
  theme(panel.grid.major.x = element_line(colour = "transparent"))
theme_update(modified_theme)
#> Error in (function (el, elname) : Element line must be a element_line object.
modified_theme <- theme_bw() +
  theme(panel.grid.major = element_blank(),
    panel.grid.major.x = element_line(colour = "transparent"))
theme_update(modified_theme)
#> Error in (function (el, elname) : Element line must be a element_line object.

^{Created on 2018-11-29 by the reprex package (v0.2.1)}

Session info

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[clauswilke]

From looking at the code of theme_update(), it looks to me that the syntax would have to be the following:

theme_update(panel.grid.major.x = element_blank())

This isn't well documented, so there's some room for improvement there.

[llrs]

Ok, I just assumed that I should pass a theme object. Probably using this as an example it might help to other readers. Thanks for the quick answer!

[ptoche]

The docs are here:

https://ggplot2.tidyverse.org/reference/theme_get.html

To perfect the docs, a few lines could be added to the bottom of the page. Below these lines:

# theme_update() and theme_replace() are similar except they
# apply directly to the current/active theme. 

Doc improvement suggestion:

# Use theme_set() to completely override the current theme.
# Use theme_update() to modify a particular theme element

theme_set(theme_classic())
p

theme_update(panel.grid.major.y = element_line(colour = "gray")) 
p

^{Created on 2018-12-15 by the reprex package (v0.2.1)}

Remark in passing: The confusion is not surprising as the docs have the following example:

old <- theme_set(theme_bw())
theme_set(old)

And this sort of thing appears to work theme_set(theme_set(theme_set(theme_bw())))

[llrs]

I think this was already solved with #3782