Minimal roman
R-bloggers 2025-11-13
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Day 11 of 30DayMapChallenge: « Minimal » (previously).
A recent dataset of Roman Empire’s road system has just been published (de Soto et al. 2025) and is updated on Itiner-e where we can download the current GeoJSON. Let’s update an old post.
library(dplyr)library(ggplot2)library(glue)library(sf)library(rnaturalearth)library(rnaturalearthhires)
Data
if (!file.exists("itiner.geojson")) { download.file("https://itiner-e.org/route-segments/download", "itiner.geojson")}roads <- read_sf("itiner.geojson") |> mutate(type = factor(type, levels = c("Main Road", "Secondary Road", "River", "Sea Lane"))) |> st_transform("EPSG:3035")# map backgroundworld <- ne_countries(scale = 50) Map
bb <- st_bbox(roads)ggplot() + geom_sf(data = world, fill = "snow2", color = "snow2") + geom_sf(data = roads, aes(color = type, linetype = type, linewidth = type)) + scale_color_manual( values = c("Main Road" = "chocolate4", "Secondary Road" = "chocolate2", "River" = "steelblue1", "Sea Lane" = "slategray1")) + scale_linetype_manual( values = c("Main Road" = 1, "Secondary Road" = 1, "River" = 1, "Sea Lane" = 2)) + scale_linewidth_manual( values = c("Main Road" = .5, "Secondary Road" = .2, "River" = .2, "Sea Lane" = .2)) + coord_sf(crs = "EPSG:3035", xlim = bb[c(1, 3)], ylim = bb[c(2, 4)]) + labs(title = "Roman roads", caption = glue("https://r.iresmi.net/ - {Sys.Date()} {st_crs(roads)$Name} data: Itiner-e doi:10.1038/s41597-025-06140-z / Natural Earth")) + theme_minimal() + theme(plot.caption = element_text(size = 6, color = "darkgrey"), legend.position = "bottom")
References
de Soto, Pau, Adam Pažout, Tom Brughmans, Peter Bjerregaard Vahlstrup, Álvaro Auir, Toon Bongers, Jens Emil Bødstrup Christoffersen, et al. 2025. “Itiner-e: A High-Resolution Dataset of Roads of the Roman Empire.” Scientific Data 12 (1): 1731. https://doi.org/10.1038/s41597-025-06140-z.
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