create_layout does not return the 3rd dimension ('z' column) when passing dim = 3

[gsimchoni]

(Hi, this is a great package, thank you!)

The dim parameter in e.g. in igraph::layout_with_fr can be 2 or 3, in case a 3D layout is desired. The call:

layout3d <- create_layout(tidy_graph, layout = "fr", dim = 3)

passes without warning, and returns a data.frame with only the x and y columns, missing the z column.

I realize the source is somewhere here but it's out of my league:

ggraph/R/layout_igraph.R

Line 115 in 8d23845

layout <- cbind(x=layout[,1], y=layout[,2], extraData[, !names(extraData) %in% c('x', 'y'), drop = FALSE])

I think:

1. If because we're dealing with ggplot2 philosophy this is intentional, there should at least be a warning, referring the user to use igraph.
2. But preferably I would change things so a 3D layout can actually be output from this function, i.e. including the z column.

Thanks.

[thomasp85]

You are correct that this is intentional due to the 2D nature of ggplot2 and a warning would probably be welcome