ルート距離の計算

2地点の住所からDirection APiを利用してルート距離(m)の計算

library(rjson)
library(RCurl)

## Loading required package: bitops

# ルートの始点と終点の住所をDirections APIのURLに変換
origin.address <- "広島県広島市南区宇品東1-1-71"
destination.address <- "広島県広島市南区霞1-2-3"
origin.address <- curlEscape(iconv(origin.address, to = "UTF-8"))
destination.address <- curlEscape(iconv(destination.address, to = "UTF-8"))
mode <- "walking"  # 移動手段(driving,walking,bicycling),ただしbicyclingは米国のみ
url <- paste("http://maps.googleapis.com/maps/api/directions/json?", "origin=", 
    origin.address, "&destination=", destination.address, "&mode=", mode, "&sensor=false&region=JP&language=ja", 
    sep = "")

# Directions APIからJSON情報取得
json <- getURL(url)

# JSONからRに緯度?経度の情報を抽出
rjson <- fromJSON(json)

# 徒歩の道のり距離
dist <- rjson$routes[[1]]$legs[[1]]$distance$value
dist

## [1] 2160

詳細なルート情報

n.step <- length(rjson$routes[[1]]$legs[[1]]$steps)
ext.dir <- function(x) {
    s.lat <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$start_location$lat
    s.lon <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$start_location$lng
    e.lat <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$end_location$lat
    e.lon <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$end_location$lng
    distance <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$distance$value  # meters
    duration <- rjson$routes[[1]]$legs[[1]]$steps[[x]]$duration$value  # seconds
    c(s.lat = s.lat, s.lon = s.lon, e.lat = e.lat, e.lon = e.lon, distance = distance, 
        duration = duration)
}
route <- t(sapply(1:n.step, ext.dir))
route

##      s.lat s.lon e.lat e.lon distance duration
## [1,] 34.37 132.5 34.37 132.5      152      114
## [2,] 34.37 132.5 34.37 132.5      534      389
## [3,] 34.37 132.5 34.37 132.5       16       11
## [4,] 34.37 132.5 34.38 132.5     1129      871
## [5,] 34.38 132.5 34.38 132.5      329      243