aq_measurements: Function for getting measurements table from the openAQ API

Description Usage Arguments Details Value Examples

View source: R/measurements.R

Description

Function for getting measurements table from the openAQ API

Usage

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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

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.

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. This can be useful if e.g. there are 2000 measurements, then first use page=1 and page=2 with limit=100 to get all measurements for your query.

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 12 columns:

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

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

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

## End(Not run)

ropensci/ropenaq documentation built on March 19, 2018, 3:27 p.m.