Class: LargeCsvReader

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ LargeCsvReader 



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# File 'lib/large_csv_reader.rb', line 7

def initialize
    @books_in_stock = []
end

Instance Attribute Details

#books_in_stock ⇒ Object

Returns the value of attribute books_in_stock.



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# File 'lib/large_csv_reader.rb', line 6

def books_in_stock
  @books_in_stock
end

Instance Method Details

#append_book_to_csv(filename, rows = 1000000) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 33

def append_book_to_csv(filename,rows=1000000)
    CSV.open(filename, "ab") do |csv|          
        self.book_generator.lazy.select {|book| csv << [Date.new(2001,2,3), book.isbn, book.price] }.first(rows)        
    end
end

#append_to_csv(filename, rows = 1000000, rowStructure) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 39

def append_to_csv(filename,rows=1000000,rowStructure)
    CSV.open(filename, "ab") do |csv|          
        self.row_generator(rowStructure).lazy.select {|row| csv << row }.first(rows)        
    end
end

#book_generator ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 69

def book_generator
    Enumerator.new do |caller|  
        testBook = BookInStock.new("978-1-9343561-0-4", 20.05)                    
        loop do
            caller.yield testBook                
        end
    end
end

#generate_csv(filename, column_names) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 27

def generate_csv(filename,column_names)       
    CSV.open(filename, "ab") do |csv|
        csv << column_names           
    end
end

#massive_book_csv_builder(filename, column_names, rowMultiplicator = "1") ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 19

def massive_book_csv_builder(filename,column_names,rowMultiplicator="1")
    generate_csv(filename,column_names)
    millions = rowMultiplicator.to_i
    millions.times do 
        append_book_to_csv(filename)
    end
end

#massive_csv_builder(filename, column_names, rowStructure, rowMultiplicator = "1") ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 11

def massive_csv_builder(filename,column_names,rowStructure,rowMultiplicator="1")
    generate_csv(filename,column_names)
    millions = rowMultiplicator.to_i
    millions.times do 
        append_to_csv(filename, rowStructure)
    end
end

#massive_number_of_each_isbn(csv_file_name) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 53

def massive_number_of_each_isbn(csv_file_name)
    counter_hash = {}
    CSV.foreach(csv_file_name, headers: true).each_slice(1).each {|row| number_of_each_isbn(counter_hash, row) }
    return counter_hash
end

#massive_read_in_csv_data(csv_file_name) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 45

def massive_read_in_csv_data(csv_file_name)
    CSV.foreach(csv_file_name, headers: true).each_slice(1).each {|row| @books_in_stock << BookInStock.new(row[0][1], row[0][2])}
end

#massive_total_value_in_stock(csv_file_name) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 49

def massive_total_value_in_stock(csv_file_name)
    CSV.foreach(csv_file_name, headers: true).each_slice(1).each.inject(0) {|sum, row| sum + row[0][2].to_f }
end

#number_of_each_isbn(counter_hash, bookInfo) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 59

def number_of_each_isbn(counter_hash, bookInfo)        
    isbn = bookInfo[0][1]
    if counter_hash.has_key?(isbn)
        counter_hash[isbn] = counter_hash[isbn]+1
    else
        counter_hash[isbn] = 1
    end        
    counter_hash
end

#row_generator(structure) ⇒ Object 



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# File 'lib/large_csv_reader.rb', line 78

def row_generator(structure)
    Enumerator.new do |caller|  
        row = structure                    
        loop do
            caller.yield row                
        end
    end
end