verb | R Documentation |
Perform Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) requests for harvesting repositories.
oaih_get_record(baseurl, identifier, prefix = "oai_dc", transform = TRUE) oaih_identify(baseurl, transform = TRUE) oaih_list_identifiers(baseurl, prefix = "oai_dc", from = NULL, until = NULL, set = NULL, transform = TRUE) oaih_list_metadata_formats(baseurl, identifier = NULL, transform = TRUE) oaih_list_records(baseurl, prefix = "oai_dc", from = NULL, until = NULL, set = NULL, transform = TRUE) oaih_list_sets(baseurl, transform = TRUE)
baseurl |
a character string giving the base URL of the repository. |
identifier |
a character string giving the unique identifier for an item in a repository. |
prefix |
a character string to specify the metadata format in
OAI-PMH requests issued to the repository. The default
( |
from, until |
character strings giving datestamps to be used as
lower or upper bounds, respectively, for datestamp-based selective
harvesting (i.e., only harvest records with datestamps in the given
range). Dates and times must be encoded using ISO 8601 in either
%F or %FT%TZ format (see |
set |
a character string giving a set to be used for selective harvesting (i.e., only harvest records in the given set). |
transform |
a logical indicating whether the OAI-PMH XML results
to “useful” R data structures via |
If the OAI-PMH request was successful, the result of the request as XML or (default) transformed to “useful” R data structures.
tryCatch({ ## Run inside tryCatch() so that checks fail gracefully if OAI-PMH ## requests time out or fail otherwise. ## ## Harvest WU Reearch metadata. baseurl <- "https://research.wu.ac.at/ws/oai" ## Identify. oaih_identify(baseurl) ## List metadata formats. oaih_list_metadata_formats(baseurl) ## List sets. sets <- oaih_list_sets(baseurl) head(sets, 20L) ## List records in the 'year 1986' set. spec <- "publications:year1986" x <- oaih_list_records(baseurl, set = spec) ## Extract the metadata. m <- x[, "metadata"] m <- oaih_transform(m[lengths(m) > 0L]) ## Find the most frequent keywords. keywords <- unlist(m[, "subject"]) keywords <- keywords[!startsWith(keywords, "/dk/atira/pure")] head(sort(table(keywords), decreasing = TRUE)) ## }, error = identity)
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