resulting png file does not reflect requested image width and height in inches

[carolinarr]

I've been exploring the camcorder package, and am puzzled by the fact that when I start gg_record with a certain size request, the resulting saved files do not match the size requested. For instance, my gg_record() statement looks like this:

library(ggplot2)
library(camcorder)

camcorder::gg_record(
    dir = 'path/to/my/folder',
    device = "png",
    scale = 1,
    width = 3.5,
    height = 2.5,
    units = "in",
    dpi = 300,
    bg = 'white',
)

# example plot
ggplot(d = ToothGrowth, aes(x = len)) +
  geom_histogram(bins = 10) 

When I open the file in the Preview application or InDesign, the size is width 14.58 inches and height 10.42 inches at 72 pixels/inch. Am I missing something?

[gkaramanis]

You’re not missing anything, the short answer is that it’s complicated!

Here’s a blog post that explains how dimensions and resolution work, I hope it’s helpful:

https://www.christophenicault.com/post/understand_size_dimension_ggplot2

[carolinarr]

That blog post is extremely helpful–thank you so much for the link!

I guess I had the wrong impression here; I thought I was avoiding those issues when using camcorder() over ggsave(), but is camcorder() essentially using ggsave() each time it records?

[gkaramanis]

Nice to hear it helped! And you're correct, camcorder uses ggsave. I'm not sure there is a way to avoid the issues, my understanding is that this is how images work in general... 🤷

[carolinarr]

Ok thank you, great to confirm. Very much appreciate your responses!