ntto

Minimal n-triples toolkit. It can:

• shrink n-triples by applying namespace abbreviations (given some rules)
• convert n-triples to line delimited JSON (.ldj)

To list the abbreviation rules, run:

$ ntto -d

To create an abbreviated NT file from an NT file, run:

$ ntto -o OUTPUT.NT -a FILE.nt

To create an abbreviated JSON file from an NT file, run:

$ ntto -a -j FILE.nt > OUTPUT.LDJ

To create an abbreviated JSON file from an NT file while ignoring conversion errors, run:

$ ntto -a -j -i FILE.nt > OUTPUT.LDJ

To create an abbreviated JSON file from an NT file while ignoring conversion errors and using a custom RULES file, run:

$ ntto -r RULES -a -j -i FILE.nt > OUTPUT.LDJ

Installation

RPM and DEB packages can be found under releases.

With a proper Go setup, a

$ go get github.com/miku/ntto/cmd/ntto

should work as well.

Usage

$ ntto
Usage: ntto [OPTIONS] FILE
  -a    abbreviate n-triples using rules
  -c    dump constructed sed command and exit
  -cpuprofile string
        write cpu profile to file
  -d    dump rules and exit
  -i    ignore conversion errors
  -j    convert nt to json
  -n string
        string to indicate empty string replacement (default "<NULL>")
  -o string
        output file to write result to
  -r string
        path to rules file, use built-in if none given
  -v    prints current version and exits
  -w int
        parallelism measure (default 4)

Mode of operation

ntto takes a RULES file (alternatively uses some hardwired rules) to abbreviate common prefixes in a n-triple file. ntto does not do the replacements itself, but outsources it to external programs, like replace or perl.

With the help of replace ntto can shorten up to 3M lines per second. The resulting file size can be up to 50% of the size of the original file.

Example rules file

$ cat RULES
# example rules file
dbp             http://dbpedia.org/resource/
gnd             http://d-nb.info/gnd/
dnbes           http://d-nb.info/standards/elementset/gnd#
dnbac           http://d-nb.info/standards/vocab/gnd/geographic-area-code#
dnbv            http://d-nb.info/standards/vocab/gnd/

viaf            http://viaf.org/viaf/
frbr            http://rdvocab.info/uri/schema/FRBRentitiesRDA/
rdgr            http://rdvocab.info/ElementsGr2/

# empty lines are ignored, as are comments

foaf            http://xmlns.com/foaf/0.1/
rdf             http://www.w3.org/1999/02/22-rdf-syntax-ns#
rdfs            http://www.w3.org/2000/01/rdf-schema#
schema          http://schema.org/
dc              http://purl.org/dc/elements/1.1/
dcterms         http://purl.org/dc/terms/

Performance data point

$ wc -l file.nt
114171541

$ time ntto -o output.nt -a file.nt
real    1m51.202s
user    1m3.626s
sys     0m13.602s

$ time ntto -a -j file.nt > output.ldj
real    15m47.872s
user    16m19.516s
sys      2m3.013s

Sometimes, less is more, but YMMV:

$ time ntto -w 2 -a -j file.nt > output.ldj
real    12m3.619s
user    15m17.422s
sys     2m14.430s