We’ve finally arrived at creating our first maps based on the data we imported and cleaned in the previous sessions. The focus of this first session lies on the package tmap to create maps.

1

Let’s start super simple. Import our enhanced district data. Create a map with only the outline of Germany and one where the districts’ borders are visible. Choose a color of your choice for both maps.

solution 

# load libraries
library(tmap)
library(sf)
library(dplyr)

# code based on the original
german_districts <- 
  sf::read_sf("./data/VG250_KRS.shp") %>% 
  dplyr::mutate(district_id = as.numeric(AGS))

attributes_districts <-  readr::read_delim("./data/attributes_districts.csv", delim = ";") 
## Rows: 400 Columns: 7
## ── Column specification ────────────────────────────────────────────────────
## Delimiter: ";"
## dbl (7): district_id, car_density, ecar_share, publictransport_meandist,...
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
german_districts_enhanced <- 
  german_districts %>% 
  dplyr::left_join(attributes_districts, by = "district_id") %>% 
  sf::st_transform(crs = 3035)


# start by setting the tmap mode to "plot" for static maps
tmap_mode("plot")   # interactive maps can be designed by changing the mode to "view"
## tmap mode set to plotting
# first maps based on geometrc features
tm_shape(german_districts_enhanced) + # call  the shapefile first
  tm_fill(col = "lightgrey") # fills the polygons without drawing borders

# ... or use tm_polygons
tm_shape(german_districts_enhanced) + 
  tm_polygons(col = "lightblue") # fills the polygons and draws borders

2

In the second step, we want to visualize some information on the German districts contained in the attribute table. Choose a column of interest and create a map. Alternate the map by:

  • add a legend title and change the color palette
  • add a title to the map and change the font color of the title
  • place the legend outside of the map at the bottom
  • change the style to process the color scale (categorization) of your attribute.
Assign your map to an object called ger_map.

Combine the following options with a plus sign:

  • add a legend title and change the color palette: tm_fill(col = "", title = "", palette = "") +
  • add a title to the map and change the font color of the title: tm_layout(title = "", title.color = "") +
  • place the legend outside: tm_legend(legend.outside = TRUE/FALSE, legend.outside.position = "")
  • change the style and categorization: style = ("cat", "fixed", "sd", "equal", "pretty", "quantile", "kmeans", "hclust", "bclust", "fisher", "jenks", "dpih", "headtails", log10_pretty", "cont")
If you run colors(), R returns the names of all built-in colors.

To assign your map to an object, use the arrow <-.

solution 

ger_map <-
tm_shape(german_districts_enhanced) + 
  tm_fill(col = "publictransport_meandist",              # "col" can be the name of a color or a column name
          title = "Mean Distances to Stops",             # add a title to the legend
          palette = "RdPu",                              # add palette  
          style = "cont")  +                             # change style 
  tm_layout(title = "Access Public Transport",           # alternate the overall layout like title
            title.color = "blue" ) +                     # changes the font color of the title +
   tm_legend(legend.outside = TRUE,                      # positions the legend outside           
            legend.outside.position = "left")            # defines legend positions 


ger_map