add_capital_distance {peacesciencer}

Add capital-to-capital distance to a data frame

Description

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

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()).

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.

Author(s)

Steven V. Miller

Examples

# just call `library(tidyverse)` at the top of the your script
library(magrittr)
cow_ddy %>% add_capital_distance()

create_stateyears() %>% add_capital_distance()