Saving ggplots objects as `.RDS` or `.RData` no longer works with 4.0.0

[LangeTo]

Hey all together,

I figured that the latest ggplot release breaks my workflows, although I'm not sure what I do is intended or a _hack_🙈.

So, my idea was to have a bunch of .R files in my directory, which handle data wrangling and plotting. The plots were then save as .RDS or .RData files and in my report.qmd I would call the plots using either load() or readRDS(). They would then be available as ggplot objects and I could still add new layers to tailor the plot for the next presentation.

However, after upgrading to ggplot 4.0.0, all I get is:

$data
...
$layers
...
$scales
...
...

Could this be related to this change?

ggsave() now returns the saved file location invisibly (#3379, @eliocamp). Note that, as a side effect, an unofficial hack + ggsave() no longer works (#4513).

As I said, I'm not sure if my workflow is actually intended but it turned out to be very helpful.

[thomasp85]

The reason for this is that ggplot2 has changed the internal representation of plots (before they were S3 objects and now they are S7). The new version doesn't know of, or understand, objects created by the old version.

In general you cannot expect to be able to save plot objects and have them work across versions. It is much better to create a function that takes the input data and creates a new plot each time

[LangeTo]

You are absolutely right. Sorry for my oversight🙋‍♂️, the plots in the .RDS and .RData files were from ggplot2 3.5.2. I didn't think about this.