aq_measurements: Function for getting measurements table from the openAQ API

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

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)

ropenaq documentation built on Jan. 13, 2021, 6:21 a.m.