Plot shortest path in genealogical tree with ggenealogy

Plots a shortest path between two mathematicians in a genealogical tree using the ggenealogy layout engine.

Usage

plot_gg_path(g, id1 = NULL, id2 = NULL, expand = 0.15)

Arguments

g

an object of class genealogy, as returned by get_genealogy().

id1

an integer(1) or character(1) with the ID of the first mathematician of interest.

id2

an integer(1) or character(1) with the ID of the second mathematician of interest.

expand

a numeric(1) with the expansion factor for the graph. This defaults to 0.15, with larger values causing the x axis to expand, smaller values for it to shrink. This is useful if the nearest common ancestor has a long name, which may cause it to be clipped when plotting: increase this expansion factor to rectify this.

Value

An object of class ("gg", "ggplot") which can be displayed, or further manipulated using additional layers or aesthetic modifications from the ggplot2 package.

Details

This function requires the ggenealogy package to be installed. It is only a "Suggests" dependency because this package supports multiple plotting approaches. The presence of this package will be verified when the function is actually called, providing an opportunity to install automatically if needed.

The shortest path between the two mathematician IDs provided is plotted, with the x position of each label determined by the year of PhD award.

NOTE: if the name of the nearest common ancestor is long, it can be clipped by ggplot2. If this occurs, increase the expand argument greater than the default of 0.15.

References

Rutter, L., VanderPlas, S., Cook, D. and Graham, M.A. (2019). “ggenealogy: An R Package for Visualizing Genealogical Data”, Journal of Statistical Software, 89(13), 1-31. doi:10.18637/jss.v089.i13 .

Wickham, H. (2016). ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York.

Examples

# First, you need to use search_id() to find the mathematician ID for the
# individual(s) you wish to plot, or visit https://mathgenealogy.org/ to look
# up in the browser.

# For example, to find the shortest genealogical path between the package
# author and my former postdoc supervisor, I would start by querying using
# both mathematician IDs
g <- get_genealogy(c(96119, 171971))
#> ⠙ Connecting to geneagrapher-core WebSocket server
#> ✔ Connecting to geneagrapher-core WebSocket server [111ms]
#> 
#> ℹ Sending query
#> ✔ Sending query [6ms]
#> 
#> ℹ 🎓 Fetching PhD data ...
#> ✔ 🎓 Full genealogy retrieved [260ms]
#> 

# Then use the plot_gg_path() function to use the underlying ggenealogy package
plot_gg_path(g)