Convert Marc21 Classification records in MARC/XML to SKOS/RDF
Project description
Python script for converting MARC 21 Classification and MARC 21 Authority records (serialized as MARCXML) to SKOS concepts.
Initially developed to support the project “Felles terminologi for klassifikasjon med Dewey”, for converting Dewey Decimal Classification (DDC) records. Issues and suggestions for generalizations and improvements are welcome!
See mapping schema for MARC21 Classification and for MARC21 Authority below.
Installation
Releases can be installed from the command line with pip:
$ pip install --upgrade mc2skos # with virtualenv or as root
$ pip install --upgrade --user mc2skos # install to ~/.local
Works with both Python 2.7 and 3.3+. See Travis for details on tested Python versions.
If lxml fails to install on Windows, try the windows installer from from PyPI.
If lxml fails to install on Unix, install system packages python-dev and libxml2-dev
Make sure the Python scripts folder has been added to your PATH.
To directly use a version from source code repository:
$ git clone https://github.com/scriptotek/mc2skos.git
$ cd mc2skos
$ pip install -e .
Usage
mc2skos infile.xml outfile.ttl # from file to file
mc2skos infile.xml > outfile.ttl # from file to standard output
Run mc2skos --help or mc2skos -h for options.
URIs
URIs are generated automatically for known concept schemes, identified from 084 $a for classification records and from 008[11] / 040 $f for authority records. To list known concept schemes:
$ mc2skos -l
To add more vocabularies, you can edit vocabularies.yml. Pull requests for adding more vocabularies are very welcome!
URIs can be also be generated on the fly from an URI template specified with option --uri. The following template parameters are recognized:
{control_number} is the 001 value
{collection} is “class”, “table” or “scheme”
{object} is a member of the classification scheme (with spaces replaced by hyphens) and part of a {collection}, such as a specific class or table.
{edition} is taken from 084 $c (with language code stripped)
To add skos:inScheme statements to all records, an URI template can be specified with option --scheme. Otherwise, it will be derived from a default template if the concept scheme is known.
To add an additional skos:inScheme statement to table records, an URI template can be specified with option --table_scheme. Otherwise, it will be derived from a default template if the concept scheme is known.
The following example is generated from a DDC table record:
<http://dewey.info/class/6--982/e21/> a skos:Concept ;
skos:inScheme <http://dewey.info/scheme/edition/e21/>,
<http://dewey.info/table/6/e21/> ;
skos:notation "T6--982" ;
skos:prefLabel "Chibchan and Paezan languages"@en .
Mapping schema for MARC21 Classification
Only a small part of the MARC21 Classification data model is converted, and the conversion follows a rather pragmatic approach, exemplified by the mapping of the 7XX fields to skos:altLabel.
MARC21XML |
RDF |
---|---|
001 Control Number |
dcterms:identifier |
005 Date and time of latest transaction |
dcterms:modified |
008[0:6] Date entered on file |
dcterms:created |
008[8]="d" or "e" Classification validity |
owl:deprecated |
153 $a, $c, $z Classification number |
skos:notation |
153 $j Caption |
skos:prefLabel |
153 $e, $f, $z Classification number hierarchy |
skos:broader |
253 Complex See Reference |
skos:editorialNote |
353 Complex See Also Reference |
skos:editorialNote |
680 Scope Note |
skos:scopeNote |
683 Application Instruction Note |
skos:editorialNote |
684 Auxiliary Instruction Note |
skos:editorialNote |
685 History Note |
skos:historyNote |
700 Index Term-Personal Name |
skos:altLabel |
710 Index Term-Corporate Name |
skos:altLabel |
711 Index Term-Meeting Name |
skos:altLabel |
730 Index Term-Uniform Title |
skos:altLabel |
748 Index Term-Chronological |
skos:altLabel |
750 Index Term-Topical |
skos:altLabel |
751 Index Term-Geographic Name |
skos:altLabel |
753 Index Term-Uncontrolled |
skos:altLabel |
765 Synthesized Number Components |
mads:componentList (see below) |
Synthesized number components
Components of synthesized numbers explicitly described in 765 fields are expressed using the mads:componentList property, and to preserve the order of the components, we use RDF lists. Example:
@prefix mads: <http://www.loc.gov/mads/rdf/v1#> .
<http://dewey.info/class/001.30973/e23/> a skos:Concept ;
mads:componentList (
<http://dewey.info/class/001.3/e23/>
<http://dewey.info/class/1--09/e23/>
<http://dewey.info/class/2--73/e23/>
) ;
skos:notation "001.30973" .
Retrieving list members in order is surprisingly hard with SPARQL. Retrieving ordered pairs is the best solution I’ve come up with so far:
PREFIX mads: <http://www.loc.gov/mads/rdf/v1#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
SELECT ?c1_notation ?c1_label ?c2_notation ?c2_label
WHERE { GRAPH <http://localhost/ddc23no> {
<http://dewey.info/class/001.30973/e23/> mads:componentList ?l .
?l rdf:rest* ?sl .
?sl rdf:first ?e1 .
?sl rdf:rest ?sln .
?sln rdf:first ?e2 .
?e1 skos:notation ?c1_notation .
?e2 skos:notation ?c2_notation .
OPTIONAL {
?e1 skos:prefLabel ?c1_label .
}
OPTIONAL {
?e2 skos:prefLabel ?c2_label .
}
}}
c1_notation |
c1_label |
c2_notation |
c2_label |
---|---|---|---|
“001.3” |
“Humaniora”@nb |
“T1–09” |
“Historie, geografisk behandling, biografier”@nb |
“T1–09” |
“Historie, geografisk behandling, biografier”@nb |
“T2–73” |
“USA”@nb |
Additional conversion rules for WebDewey data
The script comes with a few extra rules for distinguishing between different types of notes in WebDewey records and extract entities from these. The entity extraction rules (marked with [*] below) utilizes a non-standard namespace and are not enabled by default. Specify the --webdewey flag to use them.
MARC21XML |
RDF |
---|---|
680 having $9 ess=ndf Definition note |
skos:definition |
680 having $9 ess=nvn Variant name note |
wd:variantName [*] for each subfield $t |
680 having $9 ess=nch Class here note |
wd:classHere [*] for each subfield $t |
680 having $9 ess=nin Including note |
wd:including [*] for each subfield $t |
680 having $9 ess=nph Former heading |
wd:formerHeading [*] for each subfield $t |
694 having $9 ess=nml ??? |
SKOS.editorialNote |
Notes that are currently not treated in any special way:
253 having $9 ess=nsx Do-not-use.
253 having $9 ess=nce Class-elsewhere
253 having $9 ess=ncw Class-elsewhere-manual
253 having $9 ess=nse See.
253 having $9 ess=nsw See-manual.
353 having $9 ess=nsa See-also
683 having $9 ess=nbu Preference note
683 having $9 ess=nop Options note
683 having $9 ess=non Options note
684 having $9 ess=nsm Manual note
685 having $9 ess=ndp Discontinued partial
685 having $9 ess=nrp Relocation
689 having $9 ess=nru Sist brukt i…
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