Recommended packages:

  • tmap: special-purpose package for thematic maps in R. [focus]
  • ggplot: most popular package for datavis in R, recent and growing support for maps.
  • leaflet: flexible, general purpose package for interactive maps.
  • mapview: quick, single-function to interactively view spatial data(frames).

Learn more:

library(BelgiumMaps.StatBel)
library(mapview)
library(sf)
library(tmap)
library(readr)
library(dplyr)
library(ggplot2)

Thematic maps with tmap

In an nutshell:

  • Quick thematic map: qtm()
  • Build map in layers with lots of control and options: tm_shape(), tm_fill(), tm_borders(), etc.
  • Cherry-on-top: switch between interactive and static plotting with tmap_mode('view') and tmap_mode('plot').

Some resources:

Already showed some examples, here extra focus on:

  • “Layered” building of maps.
  • Binning and color scales
  • Multiple (styled) borders
  • Multiple maps

Tip: for final tweaks, save map as SVG in Inkscape.

# load boundary for entire BE
data("BE_ADMIN_BELGIUM")
be <- st_as_sf(BE_ADMIN_BELGIUM)

# load municipal boundaries
data("BE_ADMIN_MUNTY")
munip_map <- st_as_sf(BE_ADMIN_MUNTY)

# load fiscal income data on municipal level
munip_data <- read_csv(
  file = 'data/fiscal_incomes_2016.csv', 
  col_types = cols(
    munip_label = col_character(),
    munip_nis = col_character(),
    n_inhabitants = col_integer(),
    income_mean = col_integer() ))

# add map and income data together on muncipal level
munip <- left_join(
  munip_map, munip_data, 
  by = c('CD_MUNTY_REFNIS' = 'munip_nis'))

Building maps in layers

tm_shape(munip) +
  tm_borders()

tm_shape(munip) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)')

tm_shape(munip) +
  tm_borders() +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)')

tm_shape(munip) +
  tm_borders(col = 'white', lwd = 0.3) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)')

tm_shape(munip) +
  tm_borders(col = 'white', lwd = 0.3) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)', legend.hist = TRUE) +
  tm_legend(legend.outside = TRUE)

 tm_shape(munip) +
  tm_borders(col = 'white', lwd = 0.3) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)', legend.hist = TRUE) +
  tm_legend(legend.outside = TRUE) +
  tm_layout(frame = FALSE) +
  tm_credits('Source: Statbel, Fiscale statistiek van de inkomsten 2005-2016', position = 'left')

 tm_shape(munip) +
  tm_borders(col = 'white', lwd = 0.3) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)', legend.hist = FALSE) +
  tm_legend(legend.outside = FALSE) +
  tm_layout(frame = FALSE) +
  tm_credits('Source: Statbel, Fiscale statistiek van de\ninkomsten 2005-2016', position = 'center') +
  tm_style_grey(legend.format = list(text.separator= "-")) + 
  tm_logo("data/hiva_logo_400x400.png")

Add layers using objects

be_income <- tm_shape(munip) +
  tm_borders(col = 'white', lwd = 0.3) +
  tm_fill(col = 'income_mean', title = 'Mean income (2016)', legend.hist = FALSE) +
  tm_legend(legend.outside = FALSE)

be_income

be_income_style <- be_income +
  tm_layout(frame = FALSE) +
  tm_credits('Source: Statbel, Fiscale statistiek van de\ninkomsten 2005-2016', position = 'center') +
  tm_style_grey(legend.format = list(text.separator= "-")) + 
  tm_logo("data/hiva_logo_400x400.png", height = 2) +     # scale down logo size a bit
  tm_layout(scale = 0.8)                                  # reduce over text-size
## Warning in tm_style_grey(legend.format = list(text.separator =
## "-")): tm_style_grey is deprecated as of tmap version 2.0. Please use
## tm_style("grey", ...) instead
be_income_style
## Note that tm_style("grey") resets all options set with tm_layout, tm_view, tm_format, or tm_legend. It is therefore recommended to place the tm_style element prior to the other tm_layout/tm_view/tm_format/tm_legend elements.

save_tmap(be_income_style, 'output/be_income_muni_2016.png', width = 1920, height = 1080)
## Warning in save_tmap(be_income_style, "output/be_income_muni_2016.png", :
## save_tmap is deprecated as of tmap version 2.0. Please use tmap_save
## instead
## Note that tm_style("grey") resets all options set with tm_layout, tm_view, tm_format, or tm_legend. It is therefore recommended to place the tm_style element prior to the other tm_layout/tm_view/tm_format/tm_legend elements.
## Map saved to /home/rstudio/projects/thematic-maps-r/output/be_income_muni_2016.png
## Resolution: 1920 by 1080 pixels
## Size: 6.4 by 3.6 inches (300 dpi)

Styled (multiple) borders

data("BE_ADMIN_PROVINCE")
prov <- st_as_sf(BE_ADMIN_PROVINCE)
be_income_prov <- be_income +
  tm_shape(prov) +
  tm_borders(col = 'black', lwd = .2)

be_income_prov

Binning and color palettes

  • Choice of binning intervals matters.
  • Choise of color palette matters, cf. colorbrewer: sequential, diverging, and qualitative color palettes.
min(munip$income_mean)
## [1] 8835
max(munip$income_mean)
## [1] 28348
tm_shape(munip) +
  tm_fill(col = 'income_mean', 
          title = 'Mean income (2016)',
          breaks = c(0, 20000, 25000, 30000)) +
  tm_borders(col = 'white', lwd = .5)

tm_shape(munip) +
  tm_fill(col = 'income_mean', 
          title = 'Mean income (2016)',
          n=20, # detailed breaks!
          legend.hist = TRUE) +
  tm_borders(col = 'white', lwd = .5) +
  tm_legend(legend.outside = TRUE, legend.outside.position="right")

be_income_div <- tm_shape(munip) +
  tm_fill(col = 'income_mean', 
          title = 'Mean income (2016)',
          n = 20,  
          palette = "RdBu", auto.palette.mapping = FALSE, # diverging pallette!
    legend.hist = TRUE) +
  tm_borders(col = 'white', lwd = .5) +
  tm_legend(legend.outside = TRUE, legend.outside.position="right") +
  tm_shape(be) +
  tm_borders(col = 'black', lwd = 0.3) +
  tm_layout(frame = FALSE)
## Warning: The argument auto.palette.mapping is deprecated. Please use
## midpoint for numeric data and stretch.palette for categorical data to
## control the palette mapping.
be_income_div

Multiple maps / facets

Facets: more info in getting started document online.

tm_shape(munip) +
  tm_borders(col = 'white', lwd = .5) +
  tm_fill(col = c("income_mean", 'n_inhabitants')) +
  tm_layout(legend.position = c('left', 'bottom'))

m_be_income <- tm_shape(munip) +
  tm_borders(col = 'white', lwd = .5) +
  tm_fill(col = "income_mean", title = 'Mean income (2016)')

m_be_pop <- tm_shape(munip) +
  tm_borders(col = 'white', lwd = .5) +
  tm_fill(col = "n_inhabitants", title = "Population (2010)")

tmap_arrange(m_be_income, m_be_pop)

tmap interactive mode

tmap_mode('view')
be_income_div