Class: Scrubyt::ResultIndexer

Inherits:
Object
  • Object
show all
Defined in:
lib/scrubyt/core/scraping/result_indexer.rb

Overview

Selecting results based on indices

If the results is list-like (as opposed to a ‘hard’ result, like a price or a title), probably with a variable count of results (like tags, authors etc.), you may need just specific elements - like the last one, every third one, or at specific indices. In this case you should use the select_indices syntax.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ ResultIndexer

Returns a new instance of ResultIndexer.



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# File 'lib/scrubyt/core/scraping/result_indexer.rb', line 12

def initialize(*args)
  select_indices(*args)
end

Instance Attribute Details

#indices_to_extract ⇒ Object (readonly)

Returns the value of attribute indices_to_extract.



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# File 'lib/scrubyt/core/scraping/result_indexer.rb', line 10

def indices_to_extract
  @indices_to_extract
end

Instance Method Details

#select_indices_to_extract(ary) ⇒ Object

Perform selection of the desires result instances, based on their indices



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# File 'lib/scrubyt/core/scraping/result_indexer.rb', line 18

def select_indices_to_extract(ary)
  return ary if @indices_to_extract == nil
  to_keep = []
  @indices_to_extract.each {|e|
    if e.is_a? Symbol
      case e
      when :first
        to_keep << 0
      when :last
        to_keep << ary.size-1
      when :all_but_last
       (0..ary.size-2).each {|i| to_keep << i} 
      when :all_but_first
       (1..ary.size-1).each {|i| to_keep << i} 
      when :every_even
       (0..ary.size).each {|i| to_keep << i if (i % 2 == 1)}
      when :every_odd
       (0..ary.size).each {|i| to_keep << i if (i % 2 == 0)}
      when :every_second
       (0..ary.size).each {|i| to_keep << i if (i % 2 == 0)}
      when :every_third
       (0..ary.size).each {|i| to_keep << i if (i % 3 == 0)}
      when :every_fourth
       (0..ary.size).each {|i| to_keep << i if (i % 4 == 0)}
      end
    end
  }
  @indices_to_extract.each {|i| to_keep << i if !i.is_a? Symbol}
  to_keep.sort!
  ary.reject! {|e| !to_keep.include? ary.index(e)}
  ary
end