CatalogNode: A class for Catalogs (which may contain catalogs references...

In thredds: Crawler for Navigating THREDDS Catalogs

A class for Catalogs (which may contain catalogs references or datasets)

Description

A catalog representation that sublcasses from ThreddsNode

Super class

thredds::ThreddsNode -> CatalogNode

Methods

Public methods

• CatalogNode$list_services()

• CatalogNode$list_catalogs()

• CatalogNode$list_datasets()

• CatalogNode$get_catalogs()

• CatalogNode$get_datasets()

• CatalogNode$get_dataset_names()

• CatalogNode$get_catalog_names()

• CatalogNode$parse_catalog_node()

• CatalogNode$parse_dataset_node()

• CatalogNode$print()

• CatalogNode$clone()

Inherited methods

• thredds::ThreddsNode$GET()
• thredds::ThreddsNode$browse()
• thredds::ThreddsNode$children_names()
• thredds::ThreddsNode$initialize()

---

Method list_services()

list available services

Usage

CatalogNode$list_services(
  xpath = build_xpath("service", prefix = self$prefix),
  form = "list"
)

Arguments

xpath

character, the xpath specifications

form

character, either "list" or "table"

Returns

list of zero or more character vectors

---

Method list_catalogs()

list available catalogRefs

Usage

CatalogNode$list_catalogs(
  xpath = build_xpath(c("dataset", "catalogRef"), prefix = self$prefix),
  form = "list"
)

Arguments

xpath

character, the xpath descriptor

form

character, either "list" or "table"

Returns

a list with zero or more character vectors

---

Method list_datasets()

list available datasets

Usage

CatalogNode$list_datasets(
  xpath = build_xpath(c("dataset", "dataset"), prefix = self$prefix),
  form = "list"
)

Arguments

xpath

character, the xpath descriptor

form

character, either "list" or "table"

Returns

a list with zero or more character vectors

---

Method get_catalogs()

Retrieve a list one or more of child catalogs

Usage

CatalogNode$get_catalogs(
  index,
  xpath = build_xpath(c("dataset", "catalogRef"), prefix = self$prefix)
)

Arguments

index

integer index (1,...,nChild), indices or name(s)

xpath

character xpath representation

Returns

a list of Catalog class objects, possibly NULL

---

Method get_datasets()

Retrieve list one or more dataset children

Usage

CatalogNode$get_datasets(
  index,
  xpath = build_xpath(c("dataset", "dataset"), prefix = self$prefix)
)

Arguments

index

the integer index (1,...,nChild), indices or name(s)

xpath

character xpath representation

Returns

a list of Dataset objects or NULL

---

Method get_dataset_names()

Retrieve list zero or more dataset child names. If unnnamed, then we substitute "title", "ID", "urlPath", or "href" in that order of availability.

Usage

CatalogNode$get_dataset_names(
  xpath = build_xpath(c("dataset", "dataset"), prefix = self$prefix)
)

Arguments

xpath

character xpath representation

index

the integer index (1,...,nChild), indices or name(s)

Returns

character vector of zero or more names

---

Method get_catalog_names()

Retrieve list zero or more catalog child names. If unnnamed, then we substitute "title", "ID", "urlPath" or href" in that order of availability.

Usage

CatalogNode$get_catalog_names(
  xpath = build_xpath(c("dataset", "catalogRef"), prefix = self$prefix)
)

Arguments

xpath

character xpath representation

index

the integer index (1,...,nChild), indices or name(s)

Returns

character vector of zero or more names

---

Method parse_catalog_node()

Parse a catalog node

Usage

CatalogNode$parse_catalog_node(x)

Arguments

x

xml_node

Returns

Catalog class object

---

Method parse_dataset_node()

Parse a dataset node

Usage

CatalogNode$parse_dataset_node(x)

Arguments

x

xml_node

Returns

Dataset class object

---

Method print()

print method

Usage

CatalogNode$print(prefix = "")

Arguments

prefix

character, to be printed before each line of output (like spaces)

...

other arguments for superclass

---

Method clone()

The objects of this class are cloneable with this method.

Usage

CatalogNode$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

 
  library(thredds)
  top_uri <- 'https://oceandata.sci.gsfc.nasa.gov/opendap/catalog.xml'
  Top <- thredds::CatalogNode$new(top_uri)
  
  #to browse catalogue
  #Top$browse()
  
  #go down in 'MODISA' catalog
  L3 <- Top$get_catalogs("MODISA")[["MODISA"]]$get_catalogs()[[1]]
  
  #see what's available for 2009
  catalog2009 <- L3$get_catalogs("2009")[[1]]
  
  #get catalog for 2009-01-20 
  doy <- format(as.Date("2009-01-20"), "%m%d")
  catalog20 <- catalog2009$get_catalogs(doy)[[doy]]
  
  #get dataset node
  chl <- catalog20$get_datasets("AQUA_MODIS.20090120.L3m.DAY.CHL.chlor_a.4km.nc")[[1]]
  
  #retrieve the relative URL, and add it to the base URL for the service.
  #Somewhat awkwardly, the relative URL comes prepended with a path separator, so we 
  #use straight up `paste0` to append to the base_uri.
  #if(require("ncdf4")){
  #  base_uri <- "https://oceandata.sci.gsfc.nasa.gov:443/opendap"
  #  uri <- paste0(base_uri, chl[["AQUA_MODIS.20090120.L3m.DAY.CHL.chlor_a.4km.nc"]]$url)
  #  NC <- ncdf4::nc_open(uri)
  #}
 

thredds documentation built on Sept. 1, 2023, 5:08 p.m.