process_map and render=FALSE ignores layout specification

[kkmann]

Hey,

I bumped into this while trying to export my maps to pdf via 'export_graph'. It works fine but ignores custom layout specifications.

[fmannhardt]

I assume you are taking about the parameters generated with layout_pm. Indeed, this is a limitation as we are unable to set the relevant DOT attributes via the DiagrammeR library if the map is not rendered staight away, which I assume is what you need to do for the export? A reproducible example would be good to confirm this.

I already created an issue upstream here:
rich-iannone/DiagrammeR#360

For now, there is little we can do about this (except patching DiagrammeR, which I would like to avoid). We should definitely document this, but I had hoped that DiagrammeR would be updated.

You may have some success by manually applying our workaround before passing it into the export function:

	  	# hack to add 'weight' attribute to the graph
		graph$edges_df %>%
			mutate(len = weight, decorate = constraint) -> graph$edges_df

		graph %>% render_graph() -> graph

		graph$x$diagram %>%
			stringr::str_replace_all("len", "weight") %>%
			stringr::str_replace_all("decorate", "constraint") -> graph$x$diagram

[kkmann]

Yes, exactly, makes it a bit tricky to produce high quality pdf graphs for publications. Thanks for raising that with DiagrammR!