mf_get_opt_param function

Precompute the parameter opt_param of the function mf_get_url

Precompute the parameter opt_param of the function mf_get_url

Precompute the parameter opt_param to further provide as input of the mf_get_url function. Useful to speed-up the overall processing time.

mf_get_opt_param(collection, roi, credentials = NULL, verbose = "inform")

Arguments

  • collection: string. mandatory. Collection of interest (see details of mf_get_url ).
  • roi: object of class sf. mandatory. Area of region of interest. Must be a Simple feature collection with geometry type POLYGON, composed of one or several rows (i.e. one or several ROIs), and with at least two columns: 'id' (an identifier for the roi) and 'geom' (the geometry).
  • credentials: vector string of length 2 with username and password. optional if the function mf_login was previously executed.
  • verbose: string. Verbose mode ("quiet", "inform", or "debug"). Default "inform".

Returns

a list with the following named objects :

  • roiSpatialIndexBound: OPeNDAP indices for the spatial coordinates of the bounding box of the ROI (minLat, maxLat, minLon, maxLon)
  • availableVariables: Variables available for the collection of interest
  • roiSpatialBound: The spatial coordinates of the bounding box of the ROI expressed in the CRS of the collection
  • OpenDAPXVector: The X (longitude) vector
  • OpenDAPYVector: The Y (longitude) vector
  • OpenDAPtimeVector: The time vector, or NULL if the collection does not have a time vector
  • modis_tile: The MODIS tile(s) number(s) for the ROI or NULL if the collection is not MODIS

Details

When it is needed to loop the function mf_get_url over several time frames, it is advised to previously run the function mf_get_opt_param and provide the output as input opt_param parameter of the mf_get_url function. This will save much time, as internal parameters will be calculated only once.

Examples

## Not run: # Login to Earthdata log <- mf_login(credentials = c("earthdata_un", "earthdata_pw")) # Get the optional parameters for the collection MOD11A1.061 and the following roi : roi <- sf::st_as_sf( data.frame( id = "roi_test", geom = "POLYGON ((-5.82 9.54, -5.42 9.55, -5.41 8.84, -5.81 8.84, -5.82 9.54))" ), wkt = "geom", crs = 4326 ) opt_param_mod11a1 <- mf_get_opt_param("MOD11A1.061", roi) str(opt_param_mod11a1) # Now we can provide opt_param_mod11a1 as input parameter of the function mf_get_url(). time_ranges <- list( as.Date(c("2016-01-01", "2016-01-31")), as.Date(c("2017-01-01", "2017-01-31")), as.Date(c("2018-01-01", "2018-01-31")), as.Date(c("2019-01-01", "2019-01-31")) ) (urls_mod11a1 <- map(.x = time_ranges, ~ mf_get_url( collection = "MOD11A1.061", variables = c("LST_Day_1km", "LST_Night_1km", "QC_Day", "QC_Night"), roi = roi, time_range = .x, opt_param = opt_param_mod11a1 ))) ## End(Not run)
  • Maintainer: Paul Taconet
  • License: GPL (>= 3)
  • Last published: 2024-11-12