Get time series using sf objects — sits_get

Retrieve a set of time series from a data cube and and put the result in a "sits tibble", which contains both the satellite image time series and their metadata. The samples parameter must be a sf object in POINT or POLYGON geometry. If start_date and end_date are not informed, the function uses these data from the cube.

Usage

# S3 method for class 'sf'
sits_get_data(
  cube,
  samples,
  ...,
  start_date = NULL,
  end_date = NULL,
  bands = NULL,
  impute_fn = impute_linear(),
  label = "NoClass",
  label_attr = NULL,
  n_sam_pol = 30L,
  pol_avg = FALSE,
  sampling_type = "random",
  multicores = 2L,
  progress = FALSE
)

Arguments

cube: Data cube from where data is to be retrieved. (tibble of class "raster_cube").
samples: The name of a shapefile.
...: Specific parameters for specific cases.
start_date: Start of the interval for the time series - optional (Date in "YYYY-MM-DD" format).
end_date: End of the interval for the time series - optional (Date in "YYYY-MM-DD" format).
bands: Bands to be retrieved - optional (character vector).
impute_fn: Imputation function to remove NA.
label: Label to be assigned to all time series - optional
label_attr: Attribute in the sf object to be used as a polygon label.
n_sam_pol: Number of samples per polygon to be read for POLYGON or MULTIPOLYGON objects.
pol_avg: Logical: summarize samples for each polygon?
sampling_type: Spatial sampling type: random, hexagonal, regular, or Fibonacci.
multicores: Number of threads to process the time series (integer, with min = 1 and max = 2048).
progress: Logical: show progress bar?

Value

A tibble of class "sits" with set of time series <longitude, latitude, start_date, end_date, label>.

Note

For sf objects, the following parameters are relevant:

label: label to be assigned to the samples. Should only be used if all geometries have a single label.
label_attr: defines which attribute should be used as a label, required for POINT and POLYGON geometries if label has not been set.
n_sam_pol: indicates how many points are extracted from each polygon, required for POLYGON geometry (default = 15).
sampling_type: defines how sampling is done, required for POLYGON geometry (default = "random").
pol_avg: indicates if average of values for POLYGON geometry should be computed (default = "FALSE").

Examples

if (sits_run_examples()) {
    # reading a shapefile from BDC (Brazil Data Cube)
    bdc_cube <- sits_cube(
        source = "BDC",
        collection = "CBERS-WFI-16D",
        bands = c("NDVI", "EVI"),
        tiles = c("007004", "007005"),
        start_date = "2018-09-01",
        end_date = "2018-10-28"
    )
    # define a shapefile to be read from the cube
    shp_file <- system.file("extdata/shapefiles/bdc-test/samples.shp",
        package = "sits"
    )
    # read a shapefile into an sf object
    sf_object <- sf::st_read(shp_file)
    # get samples from the BDC using an sf object
    time_series_bdc <- sits_get_data(
        cube = bdc_cube,
        samples = sf_object
    )
}