R/sift_client.R

In ropenscilabs/geofilter: 'GeoJSON' Filtering

#' Sift geojson - low level client
#'
#' @export
#' @param x input, one of character string, json, list, or ...
#' @param query query
#' @return an object of class \code{character}
#' @examples
#' library(jsonlite)
#' x <- geofilter_data$filter_features
#' prettify(x)
#' sift_client(x, ".")
#' sift_client(x, "keys")
#'
#'
#' library("leaflet")
#' library("geojson")
#'
#' # get sample data
#' file <- system.file("examples", "zillow_or.geojson", package = "geofilter")
#'
#' # plot as is
#' dat <- jsonlite::fromJSON(file, FALSE)
#' leaflet() %>%
#'   addTiles() %>%
#'   addGeoJSON(dat) %>%
#'   setView(-122.8, 44.8, zoom = 8)
#'
#' # filter to features in Multnomah County only
#' json <- paste0(readLines(file), collapse = "")
#' json2 <-
#'  sift_client(json, '.features[] | select(.properties.COUNTY == "Multnomah")')
#' dat <- jsonlite::fromJSON(json2, FALSE)
#' leaflet() %>%
#'   addTiles() %>%
#'   addGeoJSON(dat) %>%
#'   setView(-122.6, 45.5, zoom = 10)
#'
#' x <- "{\"type\":\"FeatureCollection\",\"features\":[
#'  {\"type\":\"Feature\",\"geometry\":{\"type\":\"Point\",\"coordinates\":
#'  [-99.74,32.45]},\"properties\":{}}]}"
#' x <- as.geojson(x)
#' sift_client(x, ".")
#' sift_client(x, "keys")
#'
#' data(geofilter_data)
#' x <- geofilter_data$polygons_average
#' x <- as.geojson(x)
#' sift_client(x, ".")
#' sift_client(x, "keys")
#' sift_client(x, ".[]")
#' sift_client(x, ".features")
#' sift_client(x, ".features[]")
#' sift_client(x, ".features[].type")
#' sift_client(x, ".features[].properties")
#' sift_client(x, ".features[].geometry[]")

sift_client <- function(x, query) {
  UseMethod("sift_client")
}

#' @export
sift_client.default <- function(x, query) {
  stop("no 'sift_client' method for ", class(x), call. = FALSE)
}

#' @export
sift_client.character <- function(x, query) {
  unclassattr(jqr::combine(jqr::jq(x, query)))
}

#' @export
sift_client.json <- function(x, query) {
  unclassattr(jqr::combine(jqr::jq(x, query)))
}

#' @export
sift_client.geojson <- function(x, query) {
  unclassattr(jqr::combine(jqr::jq(unclass(x), query)))
}

#' @export
sift_client.list <- function(x, query) {
  unclassattr(
    jqr::combine(jqr::jq(jsonlite::toJSON(x, auto_unbox = TRUE), query))
  )
}

unclassattr <- function(x) {
  x <- unclass(x)
  attr(x, "pretty") <- NULL
  x
}