Patrick Hochstenbach
and 2 contributors

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 a special 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::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

SEE ALSO

Catmandu, Catmandu::MARC, Catmandu::XML, Catmandu::Stat

AUTHOR

Patrick Hochstenbach, <patrick.hochstenbach at ugent.be>