ACLED API Calls in R

ACLED_web_api.R

library(httr)
library(dplyr)

ACLED_call <- function(query="") {
  url <- paste0("http://acleddata.com/api/acled/read", query)
  resp <- GET(url)
  if (http_type(resp) != "application/json") {
    stop("API did not return json", call. = FALSE)
  }
  rst <- jsonlite::fromJSON(content(resp, "text",encoding = 'UTF-8'), simplifyVector = FALSE)
  if(!rst$success){
    stop("request wasn't success")
  }
  rst <- rst$data
  if(length(rst)==0L)return(NULL)
  r <- data.frame(matrix(unlist(rst),byrow = T,nrow=length(rst)),stringsAsFactors = F)
  names(r) <- names(rst[[1L]])
  r
}

ACLED_load <- function(condition = "", limit = 500L, verbose = F){
  iscomplete <- F
  all_rst <- NULL
  currenti <- 1L
  while(!iscomplete){
    if(verbose[1L]) cat(paste0(" *** Loading ACLED on condition: '",condition,"' with each bulk of ",limit,", round ",currenti,"..."))
    q <- paste0('?',condition,ifelse(condition[1L]=='','','&'),"limit=",limit[1L],"&page=",currenti)
    rst <- acled_call(q)
    if(is.null(rst) || nrow(rst)<limit){
      iscomplete <- T
    }
    currenti <- currenti + 1L
    all_rst <- bind_rows(all_rst,rst)
    if(verbose[1L]) cat("ok ***\n")
  }
  if(verbose[1L]) cat(" *** Got all ACLED data. ***\n")
  all_rst %>% tbl_df
}
if(F){
  a2016 <- acled_load("year=2016")
  a2017 <- acled_load("year=2017")
  
  # this will load everything, may take a while.
  ACLED_all <- acled_load()
}