assets_functions | R Documentation |
These functions provide support to work with STACItemCollection
and
STACItem
item objects.
assets_download()
: Downloads the assets provided by the STAC API.
assets_url()
: Returns a
character vector with each asset href. For the URL, you can add the
GDAL library drivers for the following schemes: HTTP/HTTPS files,
S3 (AWS S3) and GS (Google Cloud Storage).
assets_select()
: Selects the
assets of each item by its name (asset_names
parameter), by expressions
(...
parameter), or by a selection function (select_fn
parameter).
Note: This function can produce items with empty assets. In this case,
users can use the items_compact()
function to remove items with no
assets.
assets_rename()
: Rename each
asset using a named list or a function.
assets_download(
items,
asset_names = NULL,
output_dir = getwd(),
overwrite = FALSE,
...,
download_fn = NULL,
fn = deprecated()
)
## S3 method for class 'STACItem'
assets_download(
items,
asset_names = NULL,
output_dir = getwd(),
overwrite = FALSE,
...,
create_json = FALSE,
download_fn = NULL,
fn = deprecated()
)
## S3 method for class 'STACItemCollection'
assets_download(
items,
asset_names = NULL,
output_dir = getwd(),
overwrite = FALSE,
...,
download_fn = NULL,
create_json = TRUE,
items_max = Inf,
progress = TRUE,
fn = deprecated()
)
## Default S3 method:
assets_download(
items,
asset_names = NULL,
output_dir = getwd(),
overwrite = FALSE,
...,
create_json = FALSE,
download_fn = NULL,
fn = deprecated()
)
assets_url(items, asset_names = NULL, append_gdalvsi = FALSE)
## S3 method for class 'STACItem'
assets_url(items, asset_names = NULL, append_gdalvsi = FALSE)
## S3 method for class 'STACItemCollection'
assets_url(items, asset_names = NULL, append_gdalvsi = FALSE)
## Default S3 method:
assets_url(items, asset_names = NULL, append_gdalvsi = FALSE)
assets_select(items, ..., asset_names = NULL, select_fn = NULL)
## S3 method for class 'STACItem'
assets_select(items, ..., asset_names = NULL, select_fn = NULL)
## S3 method for class 'STACItemCollection'
assets_select(items, ..., asset_names = NULL, select_fn = NULL)
## Default S3 method:
assets_select(items, ..., asset_names = NULL, select_fn = NULL)
assets_rename(items, mapper = NULL, ...)
## S3 method for class 'STACItem'
assets_rename(items, mapper = NULL, ...)
## S3 method for class 'STACItemCollection'
assets_rename(items, mapper = NULL, ...)
## Default S3 method:
assets_rename(items, mapper = NULL, ...)
has_assets(items)
## S3 method for class 'STACItem'
has_assets(items)
## S3 method for class 'STACItemCollection'
has_assets(items)
## Default S3 method:
has_assets(items)
asset_key()
asset_eo_bands(field)
asset_raster_bands(field)
items |
a |
asset_names |
a |
output_dir |
a |
overwrite |
a |
... |
additional arguments. See details. |
download_fn |
a |
fn |
|
create_json |
a |
items_max |
a |
progress |
a |
append_gdalvsi |
a |
select_fn |
a |
mapper |
either a named |
field |
a |
Ellipsis argument (...
) appears in different assets functions and
has distinct purposes:
assets_download()
: ellipsis is used to pass
additional httr
options to GET or POST
methods, such as add_headers or
set_cookies.
assets_select()
: ellipsis is used to pass expressions that will
be evaluated against each asset metadata. Expressions must be evaluated as
a logical value where TRUE
selects the asset and FALSE
discards it.
Multiple expressions are combine with AND
operator. Expressions can
use asset
helper functions (i.e. asset_key()
, asset_eo_bands()
,
and asset_raster_bands()
). Multiple expressions are combined with
AND
operator.
WARNING: Errors in the evaluation of expressions are
considered as FALSE
.
assets_rename()
: ellipsis is used to pass named parameters
to be processed in the same way as the named list in mapper
argument.
assets_download()
: returns the same input object item
(STACItem
or STACItemCollection
) where href
properties point to
the download assets.
assets_url()
: returns a character vector with all assets href
of an item (STACItem
or STACItemCollection
).
assets_select()
: returns the same input object item
(STACItem
or STACItemCollection
) with the selected assets.
assets_rename()
: returns the same input object item
(STACItemCollection
or STACItem
) with the assets renamed.
stac_search()
, items()
, get_request()
## Not run:
# assets_download function
stac("https://brazildatacube.dpi.inpe.br/stac/") %>%
stac_search(collections = "CB4-16D-2",
datetime = "2019-06-01/2019-08-01") %>%
stac_search() %>%
get_request() %>%
assets_download(asset_names = "thumbnail", output_dir = tempdir())
## End(Not run)
## Not run:
# assets_url function
stac_item <- stac("https://brazildatacube.dpi.inpe.br/stac/") %>%
stac_search(collections = "CB4-16D-2", limit = 100,
datetime = "2017-08-01/2018-03-01",
bbox = c(-48.206,-14.195,-45.067,-12.272)) %>%
get_request() %>% items_fetch(progress = FALSE)
stac_item %>% assets_url()
## End(Not run)
## Not run:
# assets_select function
stac_item <- stac("https://brazildatacube.dpi.inpe.br/stac/") %>%
stac_search(collections = "CB4-16D-2", limit = 100,
datetime = "2017-08-01/2018-03-01",
bbox = c(-48.206,-14.195,-45.067,-12.272)) %>%
get_request() %>% items_fetch(progress = FALSE)
stac_item %>% assets_select(asset_names = "NDVI")
## End(Not run)
## Not run:
items <- stac("https://planetarycomputer.microsoft.com/api/stac/v1") %>%
stac_search(collections = c("landsat-8-c2-l2", "sentinel-2-l2a"),
bbox = c(xmin = -64.85976089, ymin = -10.49199395,
xmax = -64.79272527, ymax =-10.44736091),
datetime = "2019-01-01/2019-06-28",
limit = 50) %>%
post_request()
# Selects assets by name
items <- assets_select(items,
asset_names = c("B02", "B03", "SR_B1", "SR_B2"))
# Renames the landsat assets
items <- assets_rename(items,
SR_B1 = "blue",
SR_B2 = "green",
B02 = "blue",
B03 = "green")
# Get the assets url's
assets_url(items)
## End(Not run)
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