NAME
Catmandu::Breaker - Package that exports data in a Breaker format
SYNOPSIS
# From the command line
# Using the default breaker
$ catmandu convert JSON to Breaker < data.json
# Break a OAI-PMH harvest
$ catmandu convert OAI --url http://biblio.ugent.be/oai to Breaker
# Using a MARC breaker
$ catmandu convert MARC to Breaker --handler marc < data.mrc
# Using an XML breaker plus create a list of unique record fields
$ catmandu convert XML --path book to Breaker --handler xml --fields data.fields < t/book.xml > data.breaker
# Find the usage statistics of fields in the XML file above
$ catmandu breaker data.breaker
# Use the list of unique fields in the report
$ catmandu breaker --fields data.fields data.breaker
# verbose output
$ catmandu breaker -v data.breaker
# The breaker commands needs to know the unique fields in the dataset to build statistics.
# By default it will scan the whole file for fields. This can be a very
# time consuming process. With --maxscan one can limit the number of lines
# in the breaker file that can be scanned for unique fields
$ catmandu breaker -v --maxscan 1000000 data.breaker
# Alternatively the fields option can be used to specify the unique fields
$ catmandu breaker -v --fields 245a,022a data.breaker
$ cat data.breaker | cut -f 2 | sort -u > data.fields
$ catmandu breaker -v --fields data.fields data.breaker
DESCRIPTION
Inspired by the article "Metadata Analysis at the Command-Line" by Mark
Phillips in http://journal.code4lib.org/articles/7818 this exporter
breaks metadata records into the Breaker format which can be analyzed
further by command line tools.
BREAKER FORMAT
When breaking a input using 'catmandu convert {format} to Breaker' each
metadata fields gets transformed into a 'breaker' format:
<record-identifier><tab><metadata-field><tab><metadata-value><tab><metadatavalue>...
For the default JSON breaker the input format is broken down into
JSON-like Paths. E.g. when give this YAML input:
---
name: John
colors:
- black
- yellow
- red
institution:
name: Acme
years:
- 1949
- 1950
- 1951
- 1952
the breaker command 'catmandu convert YAML to Breaker < file.yml' will
generate:
1 colors[] black
1 colors[] yellow
1 colors[] red
1 institution.name Acme
1 institution.years[] 1949
1 institution.years[] 1950
1 institution.years[] 1951
1 institution.years[] 1952
1 name John
The first column is a counter for each record (or the content of the
_id field when present). The second column provides a JSON path to the
data (with the array-paths translated to []). The third column is the
field value.
One can use this output in combination with Unix tools like grep, sort,
cut, etc to inspect the breaker output:
$ catmandu convert YAML to Breaker < file.yml | grep 'institution.years'
Some input formats, like MARC, the JSON-path format doesn't provide
much information which fields are present in the MARC because field
names are part of the data. It is then possible to use a special
handler to create a more verbose breaker output.
For instance, without a special handler:
$ catmandu convert MARC to Breaker < t/camel.usmarc
fol05731351 record[][] LDR
fol05731351 record[][] _
fol05731351 record[][] 00755cam 22002414a 4500
fol05731351 record[][] 001
fol05731351 record[][] _
fol05731351 record[][] fol05731351
fol05731351 record[][] 082
fol05731351 record[][] 0
fol05731351 record[][] 0
fol05731351 record[][] a
With the special marc handler:
$ catmandu convert MARC to Breaker --handler marc < t/camel.usmarc
fol05731351 LDR 00755cam 22002414a 4500
fol05731351 001 fol05731351
fol05731351 003 IMchF
fol05731351 005 20000613133448.0
fol05731351 008 000107s2000 nyua 001 0 eng
fol05731351 010a 00020737
fol05731351 020a 0471383147 (paper/cd-rom : alk. paper)
fol05731351 040a DLC
fol05731351 040c DLC
fol05731351 040d DLC
For the Catmandu::PICA tools a pica handler is available.
For the Catmandu::XML tools an xml handler is available:
$ catmandu convert XML --path book to Breaker --handler xml < t/book.xml
BREAKER STATISTICS
Statistical information can be calculated from a breaker output using
the 'catmandu breaker' command:
$ catmandu convert MARC to Breaker --handler marc < t/camel.usmarc > data.breaker
$ catmandu breaker data.breaker
| name | count | zeros | zeros% | min | max | mean | median | mode | variance | stdev | uniq%| entropy |
|------|-------|-------|--------|-----|-----|------|--------|--------|----------|-------|------|---------|
| 001 | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 100 | 3.3/3.3 |
| 003 | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 10 | 0.0/3.3 |
| 005 | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 100 | 3.3/3.3 |
| 008 | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 100 | 3.3/3.3 |
| 010a | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 100 | 3.3/3.3 |
| 020a | 9 | 1 | 10.0 | 0 | 1 | 0.9 | 1 | 1 | 0.09 | 0.3 | 90 | 3.3/3.3 |
| 040a | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 10 | 0.0/3.3 |
| 040c | 10 | 0 | 0.0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 10 | 0.0/3.3 |
| 040d | 5 | 5 | 50.0 | 0 | 1 | 0.5 | 0.5 | [0, 1] | 0.25 | 0.5 | 10 | 1.0/3.3 |
The output table provides statistical information on the usage of
fields in the original format. We see that the 001 field was counted 10
times in the data set, but the 040d value is only present 5 times. The
020a is empty in 10% (zeros%) of the records. The 001 has very unique
values (entropy is maximum), but all 040c fields contain the same
information (entropy is minimum).
See Catmandu::Exporter::Stat for more information about the statistical
fields.
MODULES
* Catmandu::Exporter::Breaker
* Catmandu::Cmd::breaker
SEE ALSO
Catmandu, Catmandu::MARC, Catmandu::XML, Catmandu::Stat
AUTHOR
Patrick Hochstenbach, <patrick.hochstenbach at ugent.be>
CONTRIBUTORS
Jakob Voss, nichtich at cpan.org