Add capital-to-capital distance to a data frame — add_capital

add_capital_distance() allows you to add capital-to-capital distance to a (dyad-year, leader-year, leader-dyad-year, state-year) data frame. The capitals are coded in the cow_capitals and gw_capitals data frames, along with their latitudes and longitudes. The distance variable that emerges capdist is calculated using the "Vincenty" method (i.e. "as the crow flies") and is expressed in kilometers.

Usage

add_capital_distance(data)

Arguments

data: a data frame with appropriate peacesciencer attributes

Value

add_capital_distance() takes a (dyad-year, leader-year, leader-dyad-year, state-year) data frame and adds the capital-to-capital distance between the first state and the second state (in dyad-year data) or the minimum capital-to-capital distance for a given state in a given year. A minor note about this function: cases of capital transition are recorded in the underlying data but, in the conversion to capital-years (and eventual merging into a dyad-year data frame), the Jan. 1 capital is used for calculating distances.

Details

The function leans on attributes of the data that are provided by one of the "create" functions in this package (e.g. create_dyadyear() or create_stateyear()).

Author

Steven V. Miller

Examples


# \donttest{
# just call `library(tidyverse)` at the top of the your script
library(magrittr)
cow_ddy %>% add_capital_distance()
#> # A tibble: 2,139,270 × 4
#>    ccode1 ccode2  year capdist
#>     <dbl>  <dbl> <int>   <dbl>
#>  1      2     20  1920   2011.
#>  2      2     20  1921   2011.
#>  3      2     20  1922   2011.
#>  4      2     20  1923   2011.
#>  5      2     20  1924   2011.
#>  6      2     20  1925   2011.
#>  7      2     20  1926   2011.
#>  8      2     20  1927   2011.
#>  9      2     20  1928   2011.
#> 10      2     20  1929   2011.
#> # ℹ 2,139,260 more rows

create_stateyears() %>% add_capital_distance()
#> Warning: There were 390 warnings in `summarize()`.
#> The first warning was:
#> ℹ In argument: `mincapdist = min(.data$capdist, na.rm = TRUE)`.
#> ℹ In group 206: `ccode1 = 2`, `year = 2021`.
#> Caused by warning in `min()`:
#> ! no non-missing arguments to min; returning Inf
#> ℹ Run `dplyr::last_dplyr_warnings()` to see the 389 remaining warnings.
#> Joining with `by = join_by(ccode, year)`
#> # A tibble: 17,121 × 4
#>    ccode statenme                  year mincapdist
#>    <dbl> <chr>                    <int>      <dbl>
#>  1     2 United States of America  1816      6677.
#>  2     2 United States of America  1817      6677.
#>  3     2 United States of America  1818      6677.
#>  4     2 United States of America  1819      6677.
#>  5     2 United States of America  1820      6677.
#>  6     2 United States of America  1821      6677.
#>  7     2 United States of America  1822      6679.
#>  8     2 United States of America  1823      6679.
#>  9     2 United States of America  1824      6679.
#> 10     2 United States of America  1825      6679.
#> # ℹ 17,111 more rows
# }