Scrape NATO defense expenditure data from Wikipedia with the rvest package in R

We can all agree that Wikipedia is often our go-to site when we want to get information quick. When we’re doing IR or Poli Sci reesarch, Wikipedia will most likely have the most up-to-date data compared to other databases on the web that can quickly become out of date.

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So in R, we can scrape a table from Wikipedia and turn into a database with the rvest package .

First, we copy and paste the Wikipedia page we want to scrape into the read_html() function as a string:

nato_members <- read_html("")

Next we save all the tables on the Wikipedia page as a list. Turn the header = TRUE.

nato_tables <- nato_members %>% html_table(header = TRUE, fill = TRUE)

The table that I want is the third table on the page, so use [[two brackets]] to access the third list.

nato_exp <- nato_tables[[3]]

The dataset is not perfect, but it is handy to have access to data this up-to-date. It comes from the most recent NATO report, published in 2019.

Some problems we will have to fix.

  1. The first row is a messy replication of the header / more information across two cells in Wikipedia.
  2. The headers are long and convoluted.
  3. There are a few values in as N/A in the dataset, which R thinks is a string.
  4. All the numbers have commas, so R thinks all the numeric values are all strings.

There are a few NA values that I would not want to impute because they are probably zero. Iceland has no armed forces and manages only a small coast guard. North Macedonia joined NATO in March 2020, so it doesn’t have all the data completely.

So first, let’s do some quick data cleaning:

Clean the variable names to remove symbols and adds underscores with a function from the janitor package

nato_exp  <- nato_exp %>% clean_names()

Delete the first row. which contains some extra header text:

nato_exp <- nato_exp[-c(1),]

Rename the headers to better reflect the original Wikipedia table headings In this rename() function,

  • the first string in the variable name we want and
  • the second string is the original heading as it was cleaned from the above clean_names() function:
nato_exp <- nato_exp %>%
 rename("def_exp_millions" = "defence_expenditure_us_f",
 "def_exp_gdp" = "defence_expenditure_us_f_2",
 "def_exp_per_capita" = "defence_expenditure_us_f_3",
 "population" = "population_a",
 "gdp" = "gdp_nominal_e",
 "personnel" = "personnel_f")

Next turn all the N/A value strings to NULL. The na_strings object we create can be used with other instances of pesky missing data varieties, other than just N/A string.

na_strings <- c("N A", "N / A", "N/A", "N/ A", "Not Available", "Not available")

nato_exp <- nato_exp %>% replace_with_na_all(condition = ~.x %in% na_strings)

Remove all the commas from the number columns and convert the character strings to numeric values with a quick function we apply to all numeric columns in the data.frame.

remove_comma <- function(x) {as.numeric(gsub(",", "", x, fixed = TRUE))}

nato_exp[2:7] <- sapply(nato_exp[2:7], remove_comma)   

Next, we can calculate the average NATO score of all the countries (excluding the member_state variable, which is a character string).

We’ll exclude the NATO total column (as it is not a member_state but an aggregate of them all) and the data about Iceland and North Macedonia, which have missing values.

nato_average <- nato_exp %>%
filter(member_state != 'NATO' & member_state != 'Iceland' & member_state != 'North Macedonia') %>%
summarise_if(is.numeric, mean, na.rm = TRUE)

Re-arrange the columns so the two data.frames match:

nato_average$member_state = "NATO average"
nato_average <- nato_average %>% select(member_state, everything())

Bind the two data.frames together

nato_exp <- rbind(nato_exp, nato_average)

Create a new factor variable that categorises countries into either above or below the NATO average defense spending.

Also we can specify a category to distinguish those countries that have reached the NATO target of their defense spending equal to 2% of their GDP.

nato_exp <- nato_exp %>% 
filter(member_state != 'NATO' & member_state!= "North Macedonia" & member_state!= "Iceland") %>% 
dplyr::mutate(difference = case_when(def_exp_gdp >= 2 ~ "Above NATO 2% GDP quota", between(def_exp_gdp, 1.6143, 2) ~ "Above NATO average", between(def_exp_gdp, 1.61427, 1.61429) ~ "NATO average", def_exp_gdp <= 1.613 ~ "Below NATO average"))

Create a vector of hex colours to correspond to the different categories. I choose traffic light colors to indicate the

  • green countries (those who have reached the NATO 2% quota),
  • orange countries (above the NATO average but below the spending target) and
  • red countries (below the NATO spending average).

The blue colour is for the NATO average bar,

my_palette <- c( "Below NATO average" = "#E60000", "NATO average" = "#012169", "Above NATO average" = "#FF7800", "Above NATO 2% GDP quota" = "#4CBB17")

Finally, we create a graph with ggplot, and use the reorder() function to arrange the bars in ascending order.

NATO allies are encouraged to hit the target of 2% of gross domestic product. So, we add a geom_vline() to demarcate the NATO 2% quota.

nato_bar <- nato_exp %>% 
  filter(member_state != 'NATO' & member_state!= "North Macedonia" & member_state!= "Iceland") %>%
  ggplot(aes(x= reorder(member_state, def_exp_gdp), y = def_exp_gdp, 
fill=factor(difference))) + 
  geom_bar(stat = "identity") +
  geom_vline(xintercept = 22.55, colour="firebrick", linetype = "longdash", size = 1) +
  geom_text(aes(x=22, label="NATO 2% quota", y=3), colour="firebrick", text=element_text(size=20)) +
  labs(title = "NATO members Defense Expenditure as a percentage GDP ",
       subtitle = "Source: NATO, 2019",
       x = "NATO Member States",
       y = "Defense Expenditure (as % GDP) ")

Click here to read about adding flags to graphs with the ggimage package.


nato_exp$iso2 <- countrycode(nato_exp$member_state, "", "iso2c")

Finally, we can print out the nato_bar graph!

nato_bar + 
geom_flag(y = -0.2, aes(image = nato_exp$iso2)) +
coord_flip() +
expand_limits(y = -0.2) +
theme(legend.title = element_blank(), axis.text.x=element_text(angle=45, hjust=1)) + scale_fill_manual(values = my_palette)

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