Have you ever done a map using a GIS (Geo-Information System) framework?

And if so, what would you tell someone who is contemplating such a thing with no prior practical experience of such systems?

  • tal@lemmy.todayEnglish
    5·
    7 days ago

    I’ve done some maps in GNU R.

    Here’s a (cropped) choropleth map I did for a discussion thread about legislative representation in Europe:

    https://lemmy.today/pictrs/image/b6f28602-ab94-4901-b5e1-158061624c75.png

    source 
    if (!require("pacman")) install.packages("pacman")
pacman::p_load_gh(c("ropenscilabs/rnaturalearth",
                    "ropenscilabs/rnaturalearthdata",
                    "ropenscilabs/rnaturalearthhires"))
pacman::p_load(
            countrycode,
            dplyr,
            ggplot2,
            readr,
            rvest,
            tmap,
            tmaptools,
            viridis
        )

page <- read_html("https://en.wikipedia.org/w/index.php?title=List_of_legislatures_by_number_of_members&oldid=1010580360")

df <- html_table(html_node(page, xpath = "/html/body/div[3]/div[3]/div[5]/div[1]/table"))

df$per_capita <- df$"Population/\nLower house seats" %>% parse_number()
df$name <- df$Country

europe <- df %>% mutate(continent = countrycode(Country, origin = "country.name", destination = "continent")) %>% filter(continent == "Europe")

shapes <- ne_countries(scale = "medium")
shapes_merged <- sp::merge(shapes, europe, by.x = "name", all.x = TRUE, by.y = "name")

map <- tm_shape(shapes_merged, projection =  "epsg:3035", bbox = bb(c(-8, 34.5000, 43, 72))) +
    tm_fill(col = "per_capita", palette = plasma(256), title = "persons", legend.reverse = TRUE) +
    tm_borders(col = "black") +
    tm_scale_bar() +
    tm_layout(bg.color = "#e6f7fe", outer.margins = 0, legend.outside = TRUE,
              legend.outside.position = "bottom",
              legend.position = c(0,.9),
              main.title = "Persons per Lower House Legislative Seat",
              attr.outside = TRUE)

tmap_save(map, width =  1920, height =  1080, dpi =  96, "map.png")

    And if so, what would you tell someone who is contemplating such a thing with no prior practical experience of such systems?

    Depends pretty much entirely on what it is that you want to do and what software you’re using.

    • Jürgen Hubert@ttrpg.networkOPEnglish
      2·
      7 days ago

      The idea would be a custom fantasy world, starting with continental outlines and working my way inwards to focus regions.

      And I would use QGIS.