Retrieve Pollutant Grid(s) for a Given Time Period — temporary_grid

Retrieves the pollutant grid corresponding to a given date and time. When a time interval spanning multiple hours is provided, the function averages the pollutant values across all hourly grids and returns a single grid.

Usage

temporary_grid_search(
  start_hour,
  end_hour = NULL,
  dir,
  time_format,
  gridID,
  shapeValue
)

Arguments

start_hour: Character. Start date and time.
end_hour: Optional character. End date and time. If NULL, only the grid corresponding to start_hour is returned.
dir: Character. Directory containing the hourly grid shapefiles.
time_format: Character. Format used to parse start_hour and end_hour.
gridID: Character. Name of the field containing the grid cell identifier.
shapeValue: Character. Name of the field containing the pollutant concentration values.

Value

An sf object containing the pollutant grid corresponding to the requested hour or the average pollutant grid over the requested time interval.

Details

If start_hour and end_hour span multiple hours, the function retrieves every corresponding hourly grid, calculates the mean pollutant concentration for each grid cell, and returns the resulting averaged grid as an sf object.

The returned object is always transformed to the WGS84 geographic coordinate reference system (EPSG:4326).

Examples

if (FALSE) { # \dontrun{
temporary_grid_search(
  start_hour = "2019-08-01 08:00:00",
  end_hour = "2019-08-01 10:00:00",
  dir = "path/to/grids",
  time_format = "%Y-%m-%d %H:%M:%S",
  gridID = "ID",
  shapeValue = "PM25"
)
} # }