展开列表的data.frame列

Question

I have found myself with a data.frame containing a column of lists. Within these lists are the coordinates for a polygon; the remainder of the columns are the features of the polygons.

I would like to "spread out" the coordinate points in the lists so that I can use ggplot2 to plot the polygons and make a map, but am having trouble figuring out how to do this.

I don't really understand how the lists are structured and they are all different sizes, as the polygons have different shapes.

The data was originally a json file. I pulled it in with jsonlite package and then tried to boil it down to the relevant components like so:

library(jsonlite)

json_file <- "https://raw.githubusercontent.com/OpenOil-UG/concessionsmap/master/concessions/data/NG_contracts%2B.geojson" json_data <- jsonlite::fromJSON(json_file, simplifyDataFrame=T) data <- json_data$features data2 <- flatten(data)

This may not be the right approach starting with the json file. It is just what seemed most straightforward to me as far as taking the data from json to a data.frame I could understand.

*Edited to include real data instead of a sample

Answer 1

I would like to [...] use ggplot2 to plot the polygons and make a map

One option:

library(geojsonio)
library(ggplot2)
download.file(json_file, tf <- tempfile(fileext = ".geojson"))
df <- fortify(geojson_read(tf, what="sp"))
ggplot(df, aes(long, lat, group=group)) + 
  geom_polygon(color="white")

That gives you: