# ============================================================================== # getters for the opensensemap API. # the awesome httr library does all the curling, query and response parsing. # for CSV responses (get_measurements) the readr package is a hidden dependency # ============================================================================== #' Get the default openSenseMap API endpoint #' @export #' @return A character string with the HTTP URL of the openSenseMap API osem_endpoint = function() { 'https://api.opensensemap.org' } get_boxes_ = function (..., endpoint) { response = osem_get_resource(endpoint, path = c('boxes'), ...) if (length(response) == 0) { warning('no senseBoxes found for this query') return(osem_as_sensebox(as.data.frame(response))) } # parse each list element as sensebox & combine them to a single data.frame boxesList = lapply(response, parse_senseboxdata) df = dplyr::bind_rows(boxesList) df$exposure = df$exposure %>% as.factor() df$model = df$model %>% as.factor() if (!is.null(df$grouptag)) df$grouptag = df$grouptag %>% as.factor() df } get_box_ = function (boxId, endpoint, ...) { osem_get_resource(endpoint, path = c('boxes', boxId), ..., progress = FALSE) %>% parse_senseboxdata() } parse_measurement_csv = function (resText) { # parse the CSV response manually & mute readr suppressWarnings({ result = readr::read_csv(resText, col_types = readr::cols( # factor as default would raise issues with concatenation of multiple requests .default = readr::col_character(), createdAt = readr::col_datetime(), value = readr::col_double(), lat = readr::col_double(), lon = readr::col_double(), height = readr::col_double() )) }) osem_as_measurements(result) } get_measurements_ = function (..., endpoint) { osem_get_resource(endpoint, c('boxes', 'data'), ..., type = 'text') %>% parse_measurement_csv } get_stats_ = function (endpoint, cache) { result = osem_get_resource(endpoint, path = c('stats'), progress = FALSE, cache = cache) names(result) = c('boxes', 'measurements', 'measurements_per_minute') result } #' Get any resource from openSenseMap API, possibly cache the response #' #' @param host API host #' @param path resource URL #' @param ... All other parameters interpreted as request query parameters #' @param type Passed to httr; 'parsed' to return an R object from the response, 'text for a raw response #' @param progress Boolean whether to print download progress information #' @param cache Optional path to a directory were responses will be cached. If not NA, no requests will be made when a request for the given is already cached. #' @return Result of a Request to openSenseMap API #' @noRd osem_get_resource = function (host, path, ..., type = 'parsed', progress = T, cache = NA) { query = list(...) if (!is.na(cache)) { filename = osem_cache_filename(path, query, host) %>% paste(cache, ., sep = '/') if (file.exists(filename)) return(readRDS(filename)) } res = osem_request_(host, path, query, type, progress) if (!is.na(cache)) saveRDS(res, filename) res } osem_cache_filename = function (path, query = list(), host = osem_endpoint()) { httr::modify_url(url = host, path = path, query = query) %>% digest::digest(algo = 'sha1') %>% paste('osemcache', ., 'rds', sep = '.') } #' Purge cached responses from the given cache directory #' #' @param location A path to the cache directory, defaults to the #' sessions' \code{tempdir()} #' @return Boolean whether the deletion was successful #' #' @export #' @examples #' \donttest{ #' osem_boxes(cache = tempdir()) #' osem_clear_cache() #' #' cachedir = paste(getwd(), 'osemcache', sep = '/') #' osem_boxes(cache = cachedir) #' osem_clear_cache(cachedir) #' } osem_clear_cache = function (location = tempdir()) { list.files(location, pattern = 'osemcache\\..*\\.rds') %>% lapply(function (f) file.remove(paste(location, f, sep = '/'))) %>% unlist() %>% all() } osem_request_ = function (host, path, query = list(), type = 'parsed', progress = TRUE) { progress = if (progress && !is_non_interactive()) httr::progress() else NULL res = httr::GET(host, progress, path = path, query = query) if (httr::http_error(res)) { content = httr::content(res, 'parsed', encoding = 'UTF-8') stop(if ('message' %in% names(content)) content$message else httr::status_code(res)) } content = httr::content(res, type, encoding = 'UTF-8') }