walkshed.R

#This function was taken and slightly modified from the function in the walkscoreAPI package
#Package reference: https://cran.r-project.org/web/packages/walkscoreAPI/index.html

walkshedMod <- function(x,y,key){
     URL <- paste("http://api.walkscore.com/walk_shed?lat=",y,"&lon=",x,"&wsapikey=",key,sep="")
     X <- character(0)
     X <- c(X, scan(file = URL, what = "", sep = " ", quiet = TRUE))

     status <- X[grep("{status:",X,fixed=TRUE) + 1]
     status = gsub("}","",status,fixed = TRUE)
     status <- as.numeric(gsub(",","",status,fixed=TRUE))
     if(status==1){
       lat <- X[grep("{lat",X,fixed=TRUE) + 1]
       lat <- as.numeric(gsub(",","",lat))
       lon <- X[grep("{lat",X,fixed=TRUE) + 3]
       lon <- as.numeric(gsub("},","",lon))
       geo <- X[grep("{type:",X,fixed=TRUE) + 1]
       geo <- gsub(",","",geo)
       cstart <- grep("coordinates:",X,fixed=TRUE) + 1
       cend <- grep("radius:",X,fixed=TRUE) - 1
       lonlist <- c()
       latlist <- c()
       count <- 0
       for (i in cstart:cend){
         count <- count + 1
         if (count %% 2 == 1){
           n <- X[i]
           n <- gsub("[","",n,fixed=TRUE)
           n <- gsub(",","",n,fixed=TRUE)
           n <- as.numeric(n)
           lonlist <- c(lonlist,n)
         }
         if (count %% 2 == 0){
           n <- X[i]
           n <- gsub("]","",n,fixed=TRUE)
           n <- gsub(",","",n,fixed=TRUE)
           n <- gsub("}","",n,fixed=TRUE)
           n <- as.numeric(n)
           latlist <- c(latlist,n)
         }
       }
       coords <- data.frame(lonlist,latlist)
       rad <- X[grep("radius:",X,fixed=TRUE) + 1]
       rad <- as.numeric(gsub("},","",rad,fixed=TRUE))
       slat <- X[grep("snapped_lat:",X,fixed=TRUE) + 1]
       slat <- as.numeric(gsub(",","",slat,fixed=TRUE))
       slon <- X[grep("snapped_lon:",X,fixed=TRUE) + 1]
       slon <- as.numeric(gsub("}","",slon,fixed=TRUE))
       
       object <- list()
       class(object) <- "Walkshed"
       object$status <- status
       object$origin <- c(lon,lat)
       object$geometry <- geo
       object$coordinates <- coords
       object$radius <- rad 
       object$snappedLong <- slon
       object$snappedLat <- slat
     }else{
       object <- list()
       class(object) <- "Walkshed"
       object$status <- status
     }
     return(object)
}