#' Function for getting measurements table from the openAQ API
#'
#' @importFrom lubridate ymd ymd_hms
#' @importFrom jsonlite fromJSON
#' @template country
#' @template city
#' @template location
#' @template parameter
#' @param value_from Show results above value threshold, useful in combination with `parameter`.
#' @param value_to Show results below value threshold, useful in combination with `parameter`.
#' @template has_geo
#' @template latitude
#' @template longitude
#' @template radius
#' @param date_from Show results after a certain date. (character year-month-day, ex. '2015-12-20'). Note, since November 2017 the API only provides access to the last three months so if you need more data you need to fetch it via Amazon S3 (https://medium.com/@openaq/changes-to-the-openaq-api-and-how-to-access-the-full-archive-of-data-3324b136da8c), potentially using the aws.s3 package.
#' @param date_to Show results before a certain date. (character year-month-day, ex. '2015-12-20')
#' @param attribution Logical, whether to add a column with attribution information
#' @param averaging_period Logical, whether to add a column with averaging_period information
#' @param source_name Logical, whether to add a column with source_name information
#' @template limit
#' @template page
#'
#' @return A results data.frame (dplyr "tbl_df") with at least 12 columns:
#' \itemize{
#' \item the name of the location ("location"),
#' \item the parameter ("parameter")
#' \item the value of the measurement ("value")
#' \item the unit of the measure ("unit")
#' \item the code of country the location is in ("country"),
#' \item the city it is in ("city"),
#' \item and finally an URL encoded version of the city name ("cityURL")
#' \item and of the location name ("locationURL"),
#' \item the UTC POSIXct time ("dateUTC"),
#' \item the local POSIXct time ("dateLocal"),
#' \item its longitude ("longitude") and latitude if available ("latitude").
#' }
#' and two attributes, a meta data.frame (dplyr "tbl_df") with 1 line and 5 columns:
#' \itemize{
#' \item the API name ("name"),
#' \item the license of the data ("license"),
#' \item the website url ("website"),
#' \item the queried page ("page"),
#' \item the limit on the number of results ("limit"),
#' \item the number of results found on the platform for the query ("found")
#' }
#' and a timestamp data.frame (dplyr "tbl_df") with the query time and the last time at which the data was modified on the platform.
#' @details For queries involving a city or location argument,
#' the URL-encoded name of the city/location (as in cityURL/locationURL),
#' not its name, should be used.
#' You can query any nested combination of country/location/city (level 1, 2 and 3),
#' with only one value for each argument.
#' If you write inconsistent combination such as city="Paris" and country="IN", an error message will be returned.
#' If you write city="Delhi", you do not need to write the code of the country, unless
#' one day there is a city with the same name in another country.
#'
#' If you choose to get the attribution in the output, lines might be repeated as there might be several attributions.
#'
#' @examples
#' \dontrun{
#' output <- aq_measurements(country='IN', limit=9, city='Chennai',
#' page = 1)
#' output
#' attr(output, "meta")
#' attr(output, "timestamp")
#' }
#' @export
aq_measurements <- function(country = NULL, city = NULL, location = NULL,# nolint
parameter = NULL, has_geo = NULL, date_from = NULL,
date_to = NULL, limit = 10000, value_from = NULL,
latitude = NULL, longitude = NULL, radius = NULL,
attribution = FALSE, averaging_period = FALSE,
source_name = FALSE,
value_to = NULL, page = NULL) {
####################################################
# BUILD QUERY base URL
urlAQ <- paste0(base_url(), "measurements")
argsList <- buildQuery(country = country,
city = city,
location = location,
parameter = parameter,
has_geo = has_geo,
date_from = date_from,
date_to = date_to,
value_from = value_from,
value_to = value_to,
limit = limit,
latitude = latitude,
longitude = longitude,
radius = radius,
attribution = attribution,
averaging_period = averaging_period,
source_name = source_name,
page = page)
####################################################
# GET AND TRANSFORM RESULTS
output <- getResults(urlAQ, argsList)
tableOfResults <- output
# if no results
if (nrow(tableOfResults) != 0){
tableOfResults <- tableOfResults %>%
addCityURL() %>%
addLocationURL()
tableOfResults <- dplyr::mutate(tableOfResults,
dateUTC = lubridate::ymd_hms(.data$date.utc),
data.utc = NULL
)
if (!is.null(tableOfResults[["date.local"]])) {
tableOfResults <- dplyr::mutate(tableOfResults,
dateLocal = lubridate::ymd_hms(
strftime(
.data$date.local, "%Y-%m-%dT%H:%M:%S")
),
date.local = NULL
)
}
names(tableOfResults) <- gsub("coordinates\\.", "", names(tableOfResults))
}
####################################################
# DONE!
attr(tableOfResults, "meta") <- attr(output, "meta")
attr(tableOfResults, "timestamp") <- attr(output, "timestamp")
return(tableOfResults)
}
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