aq_measurements: Function for getting measurements table from the openAQ API

In masalmon/ropenaq: Accesses Air Quality Data from the Open Data Platform OpenAQ

Function for getting measurements table from the openAQ API

Description

Function for getting measurements table from the openAQ API

Usage

aq_measurements(
  country = NULL,
  city = NULL,
  location = NULL,
  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
)

Arguments

country	Limit results by a certain country – a two-letters code see countries() for finding code based on name.
city	Limit results by a certain city.
location	Limit results by a certain location.
parameter	Limit to only a certain parameter (valid values are 'pm25', 'pm10', 'so2', 'no2', 'o3', 'co' and 'bc'). If no parameter is given, all parameters are retrieved.
has_geo	Filter out items that have or do not have geographic information.
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.
date_to	Show results before a certain date. (character year-month-day, ex. '2015-12-20')
limit	Change the number of results returned, max is 10000 by page. If no page value, then all results or limit * 100 (maximal number of pages) is returned.
value_from	Show results above value threshold, useful in combination with parameter.
latitude	Latitude of the center point (lat, lon) used to get measurements within a certain area.
longitude	Longitude of the center point (lat, lon) used to get measurements within a certain area.
radius	Radius (in meters) used to get measurements within a certain area, must be used with latitude and longitude
attribution	Logical, whether to add a column with attribution information
averaging_period	Logical, whether to add a column with averaging_period information
source_name	Logical, whether to add a column with source_name information
value_to	Show results below value threshold, useful in combination with parameter.
page	The page of the results to query (max 100).

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.

Value

A results data.frame (dplyr "tbl_df") with at least 12 columns:

• the name of the location ("location"),

• the parameter ("parameter")

• the value of the measurement ("value")

• the unit of the measure ("unit")

• the code of country the location is in ("country"),

• the city it is in ("city"),

• and finally an URL encoded version of the city name ("cityURL")

• and of the location name ("locationURL"),

• the UTC POSIXct time ("dateUTC"),

• the local POSIXct time ("dateLocal"),

• its longitude ("longitude") and latitude if available ("latitude").

and two attributes, a meta data.frame (dplyr "tbl_df") with 1 line and 5 columns:

• the API name ("name"),

• the license of the data ("license"),

• the website url ("website"),

• the queried page ("page"),

• the limit on the number of results ("limit"),

• 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.

Examples

## Not run: 
output <- aq_measurements(country='IN', limit=9, city='Chennai',
                          page = 1)
output
attr(output, "meta")
attr(output, "timestamp")

## End(Not run)

masalmon/ropenaq documentation built on May 17, 2022, 4:43 a.m.