Class: Converter

Inherits:
Object
  • Object
show all
Defined in:
lib/csv2rdf/converter.rb

Overview

Abstract super-class for all converters.

Usage

Usually, a converter will be used as follows:

converter = RatingConverter.new("path/to/file.csv", "path/to/output_file.nt", context_object)
converter.convert
converter.serialize

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(csv_in, out_file, context = nil) ⇒ Converter

Attributes

  • csv_in - Path to the CSV file that is going to be converted. Is tested for existence and type, might raise an IOError.

  • out_file - Path to the desired output file. The containing folder is tested for existence, might raise an IOError.

  • context - Optionally a context Hash, can be used to pass information to the converter.

  • log - the Logger object, defaults to STDOUT



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# File 'lib/csv2rdf/converter.rb', line 29

def initialize(csv_in, out_file, context=nil)
  unless (File.exists?(csv_in))
    raise IOError, "file '#{csv_in}' does not exist"
  end
  unless (File.file?(csv_in))
    raise IOError, "'#{csv_in}' is not a regular file"
  end
  unless (File.exists?(File.dirname(out_file)))
    raise IOError, "directory '#{File.dirname(out_file)}' does not exist"
  end
  @csv_in = csv_in
  @rdf_out = out_file
  @context = context
  @graph = RDF::Graph.new
  @log = Logger.new(STDOUT)
  @log.info("#{self.class}: converting #{@csv_in} to #{@rdf_out}")
end

Instance Attribute Details

#log ⇒ Object

The Logger object, defaults to STDOUT



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# File 'lib/csv2rdf/converter.rb', line 18

def log
  @log
end

Class Method Details

.german_to_english_float(float) ⇒ Object

Convert the string of a German-style float (“1,59”) into an actual float. If passed an actual float, it will just return it.

Attributes

  • float - the string to be converted

Examples

Converter.german_to_english_float("1,59")
 => 1.59



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# File 'lib/csv2rdf/converter.rb', line 83

def Converter.german_to_english_float(float)
  return float.to_s.gsub(",", ".").to_f
end

.ja_nein(string) ⇒ Object

Convert a string into a boolean For string.downcase == “ja” the method will return TRUE, for all other values it will return FALSE

Attributes

  • string - the string to be converted

Examples

Converter.ja_nein("ja")
 => true
Converter.ja_nein("Ja")
 => true
Converter.ja_nein("nein")
 => false
Converter.ja_nein("hurtz")
 => false



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# File 'lib/csv2rdf/converter.rb', line 106

def Converter.ja_nein(string)
  return string.downcase.eql?("ja")
end

.name2uri(name, capitalize = FALSE) ⇒ Object

Turn any string into a URI component, useful for creating URIs from names and titles. The conversion is based on ActiveSupport’s parameterize method.

Attributes

  • name - the string to be converted

  • capitalize - if TRUE, the individual components of the name will be capitalized

Examples

Converter.name2uri("Knud Möller")
 => "knud-moller"

Converter.name2uri("Knud Möller", TRUE)
 => "Knud-Moller"



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# File 'lib/csv2rdf/converter.rb', line 63

def Converter.name2uri(name, capitalize=FALSE)
  name = name.parameterize.downcase
  if capitalize
    name = name.split("-").map { |x| x.capitalize }.join("-")
  end
  return name
end

Instance Method Details

#convert ⇒ Object

The actual conversion takes place in this method. Implementations in sub-classes need to build the output graph on the graph instance variable.



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# File 'lib/csv2rdf/converter.rb', line 113

def convert
  raise "method #{self.class.name}#convert() is not implemented!"
end

#serialize ⇒ Object

After calling convert, serialize will write the graph to the desired output path (rdf_out) as an N-Triples file (www.w3.org/TR/n-triples/).



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# File 'lib/csv2rdf/converter.rb', line 120

def serialize
  RDF::Writer.open(@rdf_out) { |writer| writer << @graph }
end