Module: Traject::Macros::Marc21Semantics

Defined in:
lib/traject/macros/marc21_semantics.rb

Overview

extracting various semantic parts out of a Marc21 record. Few of these come directly from Marc21 spec or other specs with no judgement, they are all to some extent opinionated, based on actual practice and actual data, some more than others. If it doens't do what you want, don't use it. But if it does, you can use it, and continue to get updates with future versions of Traject.

Constant Summary collapse

MarcExtractor =

shortcut

Traject::MarcExtractor
OCLCPAT =

If a num begins with a known OCLC prefix, return it without the prefix. otherwise nil.

Allow (OCoLC) and/or ocn/ocm/on

/
      \A\s*
      (?:(?:\(OCoLC\)) |
(?:\(OCoLC\))?(?:(?:ocm)|(?:ocn)|(?:on))
)(\d+)
/x
LCC_REGEX =

REGEX meant to rule out obvious non-LCC's, and only allow things plausibly LCC's.

/\A *[A-Z]{1,3}[ .]*(?:(\d+)(?:\s*?\.\s*?(\d+))?).*/

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.assemble_lcsh(marc_field, subd_separator = " — ", other_separator = " ") ⇒ Object

Takes a MARC::Field and formats it into a pre-coordinated LCSH string with subdivision seperators in the right place.

For 600 fields especially, need to not just join with subdivision seperator to take acount of $a$d$t -- for other fields, might be able to just join subfields, not sure.

WILL strip trailing period from generated string, contrary to some LCSH practice. Our data is inconsistent on whether it has period or not, this was the easiest way to standardize.

Default subdivision seperator is em-dash with spaces, set to '--' if you want.

Cite: "Dash (-) that precedes a subdivision in an extended 600 subject heading is not carried in the MARC record. It may be system generated as a display constant associated with the content of subfield $v, $x, $y, and $z." http://www.loc.gov/marc/bibliographic/bd600.html


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# File 'lib/traject/macros/marc21_semantics.rb', line 562

def self.assemble_lcsh(marc_field, subd_separator = "", other_separator = " ")
  str = ""
  subd_prefix_codes = %w{v x y z}


  marc_field.subfields.each_with_index do |sf, i|
    # ignore non-alphabetic, like numeric control subfields
    next unless /\A[a-z]\Z/.match(sf.code)

    prefix = if subd_prefix_codes.include? sf.code
      subd_separator
    elsif i == 0
      ""
    else
      other_separator
    end
    str << prefix << sf.value
  end

  str.gsub!(/\.\Z/, '')

  return nil if str == ""

  return str
end

.filing_version(field, str, spec) ⇒ Object

Take in a field, a string extracted from that field, and a spec and return the filing version (i.e., the string without the non-filing characters)


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# File 'lib/traject/macros/marc21_semantics.rb', line 158

def self.filing_version(field, str, spec)
  # Control fields don't have non-filing characters
  return str if field.kind_of? MARC::ControlField

  # 2nd indicator must be > 0
  ind2 = field.indicator2.to_i
  return str unless ind2 > 0

  # The spechash must either (a) have no subfields specified, or
  # (b) include the first subfield in the record

  subs = spec.subfields
  return str unless subs && subs.include?(field.subfields[0].code)

  # OK. If we got this far we actually need to strip characters off the string

  return str[ind2..-1]
end

.get_sortable_author(record) ⇒ Object


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# File 'lib/traject/macros/marc21_semantics.rb', line 72

def self.get_sortable_author(record)
  onexx = MarcExtractor.cached("100:110:111", :first => true, :trim_punctuation => true).extract(record).first
  onexx = onexx.strip if onexx

  titles = []
  MarcExtractor.cached("240:245", :first => true).each_matching_line(record) do |field, spec|
    non_filing = field.indicator2.to_i

    str = field.subfields.collect {|sf| Marc21.trim_punctuation(sf.value.strip).strip}.join(" ")
    str = str.slice(non_filing, str.length)
    titles << str
  end.first
  title = titles.first
  title = title.strip if title

  return [onexx, title].compact.join("   ")
end

.get_sortable_title(record) ⇒ Object


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# File 'lib/traject/macros/marc21_semantics.rb', line 99

def self.get_sortable_title(record)
  MarcExtractor.cached("245ab").collect_matching_lines(record) do |field, spec, extractor|
    str = extractor.collect_subfields(field, spec).first

    if str.nil?
      # maybe an APPM archival record with only a 'k'
      str = field['k']
    end
    if str.nil?
      # still? All we can do is bail, I guess
      return nil
    end

    non_filing = field.indicator2.to_i
    str = str.slice(non_filing, str.length)
    str = Marc21.trim_punctuation(str)

    str
  end.first
end

.oclcnum_extract(num) ⇒ Object


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# File 'lib/traject/macros/marc21_semantics.rb', line 42

def self.oclcnum_extract(num)
  if m = OCLCPAT.match(num)
    return m[1]
  else
    return nil
  end
end

.publication_date(record, estimate_tolerance = 15, min_year = 500, max_year = (Time.new.year + 6)) ⇒ Object

See #marc_publication_date. Yeah, this is a holy mess. Maybe it should actually be extracted to it's own class!


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# File 'lib/traject/macros/marc21_semantics.rb', line 323

def self.publication_date(record, estimate_tolerance = 15, min_year = 500, max_year = (Time.new.year + 6))
  field008 = MarcExtractor.cached("008").extract(record).first
  found_date = nil

  if field008 && field008.length >= 11
    date_type = field008.slice(6)
    date1_str = field008.slice(7,4)
    date2_str = field008.slice(11, 4) if field008.length > 15

    # for date_type q=questionable, we have a range.
    if (date_type == 'q')
      # make unknown digits at the beginning or end of range,
      date1 = date1_str.sub("u", "0").to_i
      date2 = date2_str.sub("u", "9").to_i
      # do we have a range we can use?
      if (date2 > date1) && ((date2 - date1) <= estimate_tolerance)
        found_date = (date2 + date1)/2
      end
    end
    # didn't find a date that way, and anything OTHER than date_type
    # n=unknown, q=questionable, try single date -- for some date types,
    # there's a date range between date1 and date2, yeah, we often take
    # the FIRST date then, the earliest. That's just what we're doing.
    if found_date.nil? && date_type != 'n' && date_type != 'q'
      # in date_type 'r', second date is original publication date, use that I think?
      date_str = ((date_type == 'r' || date_type == 'p') && date2_str.to_i != 0) ? date2_str : date1_str
      # Deal with stupid 'u's, which end up meaning a range too,
      # find midpoint and make sure our tolerance is okay.
      ucount = 0
      while (!date_str.nil?) && (i = date_str.index('u'))
        ucount += 1
        date_str[i] = "0"
      end
      date = date_str.to_i
      if ucount > 0 && date != 0
        delta = 10 ** ucount # 10^ucount, expontent
        if delta <= estimate_tolerance
          found_date = date + (delta/2)
        end
      elsif date != 0
        found_date = date
      end
    end
  end
  # Okay, nothing from 008, first try 264, then try 260
  if found_date.nil?
    v264c = MarcExtractor.cached("264c", :separator => nil).extract(record).first
    v260c = MarcExtractor.cached("260c", :separator => nil).extract(record).first
    # just try to take the first four digits out of there, we're not going to try
    # anything crazy.
    if m = /(\d{4})/.match(v264c)
      found_date = m[1].to_i
    elsif m = /(\d{4})/.match(v260c)
        found_date = m[1].to_i
    end
  end

  # is it within our acceptable range?
  found_date = nil if found_date && (found_date < min_year || found_date > max_year)

  return found_date
end

Instance Method Details

#extract_marc_filing_version(spec = '245abdefghknp', opts = {}) ⇒ Object

A generic way to strip a filing version (i.e., a string with the non-filing characters stripped off)

Always returns an array. If :include_original=>true is passed in, that array will include the original string with the non-filing characters still in it.


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# File 'lib/traject/macros/marc21_semantics.rb', line 129

def extract_marc_filing_version(spec='245abdefghknp', opts={})
  include_original = opts.delete(:include_original)
  if opts.size > 0
    raise RuntimeError.new("extract_marc_filing_version can take only :include_original as an argument, not #{opts.keys.map{|x| "'#{x}'"}.join(' or ')}")
  end

  extractor = Traject::MarcExtractor.cached(spec, opts)

  lambda do |record, accumulator, context|
    extractor.collect_matching_lines(record) do |field, spec|
      str = extractor.collect_subfields(field, spec).first
      next unless str and !str.empty?
      vals = [Marc21Semantics.filing_version(field, str, spec)]
      if include_original
        vals.unshift str
        vals.uniq!
      end
      accumulator.concat vals
    end
  end
end

#marc_era_facetObject

Opinionated routine to create values for a chronology/era facet out of LCSH chron subdivisions. Does some normalization: for 651 with a chron facet fitting the form "aaaaa, yyyy-yyyy", it will add in the $a. For instance: 651 a| United States x| History y| Civil War, 1861-1865 --> "United States: Civil War, 1861-1865"


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# File 'lib/traject/macros/marc21_semantics.rb', line 489

def marc_era_facet
  ordinary_fields_spec = "600y:610y:611y:630y:648ay:650y:654y:656y:690y"
  special_fields_spec = "651:691"
  separator = ": "

  extractor_ordinary_fields = MarcExtractor.new(ordinary_fields_spec)
  extractor_special_fields  = MarcExtractor.new(special_fields_spec)

  lambda do |record, accumulator|
    # straightforward ones


    accumulator.concat( extractor_ordinary_fields.extract(record).collect do |v|
      # May have a period we have to remove, if it was at end of tag
      v.sub(/\. *\Z/, '')
    end)

    # weird ones
    special_fields_regex = /\A\s*.+,\s+(ca.\s+)?\d\d\d\d?(-\d\d\d\d?)?( B\.C\.)?[.,; ]*\Z/
    extractor_special_fields.each_matching_line(record) do |field, spec, extractor|
      field.subfields.each do |sf|
        next unless sf.code == 'y'
        if special_fields_regex.match(sf.value)
          # it's our pattern, add the $a in please
          accumulator << "#{field['a']}#{separator}#{sf.value.sub(/\. *\Z/, '')}"
        else
          accumulator << sf.value.sub(/\. *\Z/, '')
        end
      end
    end
    accumulator.uniq!
  end
end

#marc_geo_facet(options = {}) ⇒ Object

An opinionated method of making a geographic facet out of BOTH 048 marc codes, AND geo subdivisions in 6xx LCSH subjects.

The LCSH geo subdivisions are further normalized:

  • geo qualifiers in $z fields into parens, so "Germany -- Berlin" becomes "Berlin (Germany)" (to be consistent with how same areas are written in $a fields -- doesn't get everything, but gets lots of em)
  • qualified regions like that are additionally 'posted up', so "Germany -- Berlin" gets recorded additionally as "Germany"

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# File 'lib/traject/macros/marc21_semantics.rb', line 434

def marc_geo_facet(options = {})
  marc_geo_map = Traject::TranslationMap.new("marc_geographic")

  a_fields_spec = options[:geo_a_fields] || "651a:691a"
  z_fields_spec = options[:geo_z_fields] || "600:610:611:630:648:650:654:655:656:690:651:691"

  extractor_043a      = MarcExtractor.new("043a", :separator => nil)
  extractor_a_fields  = MarcExtractor.new(a_fields_spec, :separator => nil)
  extractor_z_fields  = MarcExtractor.new(z_fields_spec)

  lambda do |record, accumulator|

    accumulator.concat(
      extractor_043a.extract(record).collect do |code|
        # remove any trailing hyphens, then map
        marc_geo_map[code.gsub(/\-+\Z/, '')]
      end.compact
    )

    #LCSH 651a and 691a go in more or less normally.
    accumulator.concat(
      extractor_a_fields.extract(record).collect do |s|
        # remove trailing periods, which they sometimes have if they were
        # at end of LCSH.
        s.sub(/\. */, '')
      end
    )

    # fields we take z's from have a bit more normalization
    extractor_z_fields.each_matching_line(record) do |field, spec, extractor|
      z_fields = field.subfields.find_all {|sf| sf.code == "z"}.collect {|sf| sf.value }
      # depending on position in total field, may be a period on the end
      # we want to remove.
      z_fields.collect! {|s| s.gsub(/\. *\Z/, '')}

      if z_fields.length == 2
        # normalize subdivision as parenthetical
        accumulator << "#{z_fields[1]} (#{z_fields[0]})"
        # and 'post up'
        accumulator << z_fields[0]
      else
        # just add all the z's if there's 1 or more than 2.
        accumulator.concat z_fields
      end
    end
    accumulator.uniq!
  end
end

#marc_instrument_codes_normalized(spec = "048") ⇒ Object

This weird one actually returns marc instrumentation codes, not humanized. But it normalizes them by breaking them down into a numeric and non-numeric version. For instance "ba01" will be indexed as both "ba01" and "ba". ALSO, if the code is in a subfield b (soloist), it'll be indexed additionally as "ba01.s" and "ba.s".

This has proven useful for expert music librarian searching by hand; it could also be the basis of a GUI that executes searches behind the scenes for these codes.


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# File 'lib/traject/macros/marc21_semantics.rb', line 269

def marc_instrument_codes_normalized(spec = "048")
  soloist_suffix = ".s"

  extractor = MarcExtractor.new("048", :separator => nil)

  return lambda do |record, accumulator|
    accumulator.concat(
      extractor.collect_matching_lines(record) do |field, spec, extractor|
        values = []

        field.subfields.each do |sf|
          v = sf.value
          # Unless there's at least two chars, it's malformed, we can
          # do nothing
          next unless v.length >= 2

          # Index both with and without number -- both with soloist suffix
          # if in a $b
          values << v
          values << "#{v}#{soloist_suffix}" if sf.code == 'b'
          if v.length >= 4
            bare = v.slice(0,2) # just the prefix
            values << bare
            values << "#{bare}#{soloist_suffix}" if sf.code == 'b'
          end
        end
        values
      end.uniq
    )
  end
end

#marc_instrumentation_humanized(spec = "048ab", options = {}) ⇒ Object

Takes marc 048ab instrument code, and translates it to human-displayable string. Takes first two chars of 048a or b, to translate (ignores numeric code)

Pass in custom spec if you want just a or b, to separate soloists or whatever.


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# File 'lib/traject/macros/marc21_semantics.rb', line 246

def marc_instrumentation_humanized(spec = "048ab", options = {})
  translation_map = Traject::TranslationMap.new(options[:translation_map] || "marc_instruments")

  extractor = MarcExtractor.new(spec, :separator => nil)

  lambda do |record, accumulator|
    values = extractor.extract(record)
    human = values.collect do |value|
      translation_map[ value.slice(0, 2) ]
    end.uniq
    accumulator.concat human if human && human.length > 0
  end
end

#marc_languages(spec = "008[35-37]:041a:041d") ⇒ Object

maps languages, by default out of 008[35-37] and 041a and 041d

Can specify other spec if you want, say, 041b (lang of abstract) or 041e (lang of librettos), or 041h (lang of original) instead or in addition.

de-dups values so you don't get the same one twice.

Exact spec of #marc_languages may change with new user data on what works best.


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# File 'lib/traject/macros/marc21_semantics.rb', line 189

def marc_languages(spec = "008[35-37]:041a:041d")
  translation_map = Traject::TranslationMap.new("marc_languages")

  extractor = MarcExtractor.new(spec, :separator => nil)

  lambda do |record, accumulator|
    codes = extractor.collect_matching_lines(record) do |field, spec, extractor|
      if extractor.control_field?(field)
        (spec.bytes ? field.value.byteslice(spec.bytes) : field.value)
      else
        extractor.collect_subfields(field, spec).collect do |value|
          # sometimes multiple language codes are jammed together in one subfield, and
          # we need to separate ourselves. sigh.
          unless value.length == 3
            # split into an array of 3-length substrs; JRuby has problems with regexes
            # across threads, which is why we don't use String#scan here.
            value = value.chars.each_slice(3).map(&:join)
          end
          value
        end.flatten
      end
    end
    codes = codes.uniq

    translation_map.translate_array!(codes)

    accumulator.concat codes
  end
end

#marc_lcc_to_broad_category(options = {}, spec = "050a:060a:090a:096a") ⇒ Object

Looks up Library of Congress Classification (LCC) or NLM Medical Subject Headings (MeSH) from usual parts of the marc record. Maps them to high-level broad categories, basically just using the first part of the LCC. Note it's just looking in bib-level locations for LCCs, you're on your own with holdings.

Sanity checks to make sure the thing looks like an LCC with a regex, before mapping.

Will call it 'Unknown' if it's got nothing else, or pass in :default => something else, or nil.

The categories output aren't great, but they're something.


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# File 'lib/traject/macros/marc21_semantics.rb', line 401

def marc_lcc_to_broad_category( options = {}, spec="050a:060a:090a:096a")
  # Trying to match things that look like LCC, and not match things
  # that don't. Is tricky.
  lcc_regex = LCC_REGEX
  default_value = options.has_key?(:default) ? options[:default] : "Unknown"
  translation_map = Traject::TranslationMap.new("lcc_top_level")

  extractor = MarcExtractor.new(spec, :separator => nil)

  lambda do |record, accumulator|
    candidates = extractor.extract(record)

    candidates.reject! do |candidate|
      !(lcc_regex.match candidate)
    end

    accumulator.concat translation_map.translate_array!(candidates.collect {|a| a.lstrip.slice(0, 1)}).uniq

    if default_value && accumulator.empty?
      accumulator << default_value
    end
  end
end

#marc_lcsh_formatted(options = {}) ⇒ Object

Extracts LCSH-carrying fields, and formatting them as a pre-coordinated LCSH string, for instance suitable for including in a facet.

You can supply your own list of fields as a spec, but for significant customization you probably just want to write your own method in terms of the Marc21Semantics.assemble_lcsh method.


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# File 'lib/traject/macros/marc21_semantics.rb', line 530

def marc_lcsh_formatted(options = {})
  spec            = options[:spec] || "600:610:611:630:648:650:651:654:662"
  subd_separator  = options[:subdivison_separator] || ""
  other_separator = options[:other_separator] || " "

  extractor       = MarcExtractor.new(spec)

  return lambda do |record, accumulator|
    accumulator.concat( extractor.collect_matching_lines(record) do |field, spec|
      Marc21Semantics.assemble_lcsh(field, subd_separator, other_separator)
    end)
  end

end

#marc_publication_date(options = {}) ⇒ Object

An opinionated algorithm for getting a SINGLE publication date out of marc

  • Prefers using 008, but will resort to 260c
  • If 008 represents a date range, will take the midpoint of the range, only if range is smaller than estimate_tolerance, default 15 years.
  • Ignores dates below min_year (default 500) or above max_year (this year plus 6 years), because experience shows too many of these were in error.

Yeah, this code ends up ridiculous.


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# File 'lib/traject/macros/marc21_semantics.rb', line 310

def marc_publication_date(options = {})
  estimate_tolerance  = options[:estimate_tolerance] || 15
  min_year            = options[:min_year] || 500
  max_year            = options[:max_year] || (Time.new.year + 6)

  lambda do |record, accumulator|
    date = Marc21Semantics.publication_date(record, estimate_tolerance, min_year, max_year)
    accumulator << date if date
  end
end

#marc_series_facet(spec = "440a:490a:800abcdt:810abcdt:811acdeft:830adfgklmnoprst") ⇒ Object

Adds in marc fields in spec (default is recommended series spec, but you can specify your own) -- only trick is that 490's are skipped of first indicator is 1 -- if 490 first indicator is "1", "series traced", that means the series title mentioned here is already covered by another field we're including, so we don't want to double count it, possibly with slight variation.


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# File 'lib/traject/macros/marc21_semantics.rb', line 224

def marc_series_facet(spec = "440a:490a:800abcdt:810abcdt:811acdeft:830adfgklmnoprst")
  extractor = MarcExtractor.new(spec)

  lambda do |record, accumulator|
    values = extractor.collect_matching_lines(record) do |field, spec, extractor|
      extractor.collect_subfields(field, spec) unless (field.tag == "490" && field.indicator1 == "1")
    end.compact

    # trim punctuation
    values.collect! do |s|
      Marc21.trim_punctuation(s)
    end

    accumulator.concat( values )
  end
end

#marc_sortable_authorObject

A sortable author value, created by concatenating:

  • the main entry author, if there is one (fields 100, 110 or 111)
  • the main entry uniform title (240), if there is one - not including non-filing chars as noted in 2nd indicator of the 240
    • If no 240, the 245 title, not including non-filing chars as noted in ind 2 of the 245

Always returns a SINGLE string, based on concatenation.

Thanks SolrMarc for basic logic.

Note: You'll want to pay attention to the Solr schema field definition you're using, and have it do case-insensitivity or any other normalization you might want.

these probably should be taking only certain subfields, but we're copying from SolrMarc that didn't do so either and nobody noticed, so not bothering for now.


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# File 'lib/traject/macros/marc21_semantics.rb', line 66

def marc_sortable_author
  lambda do |record, accumulator|
    accumulator << Marc21Semantics.get_sortable_author(record)
  end
end

#marc_sortable_titleObject

245 a and b, with non-filing characters stripped off


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# File 'lib/traject/macros/marc21_semantics.rb', line 92

def marc_sortable_title
  lambda do |record, accumulator|
    st = Marc21Semantics.get_sortable_title(record)
    accumulator << st if st
  end
end

#oclcnum(extract_fields = "035a") ⇒ Object

Extract OCLC numbers from, by default 035a's by known prefixes, then stripped just the num, and de-dup.


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# File 'lib/traject/macros/marc21_semantics.rb', line 18

def oclcnum(extract_fields = "035a")
  extractor = MarcExtractor.new(extract_fields, :separator => nil)

  lambda do |record, accumulator|
    list = extractor.extract(record).collect! do |o|
      Marc21Semantics.oclcnum_extract(o)
    end.compact

    accumulator.concat list.uniq if list
  end
end