Question

I am currently following Beginning Ruby by Peter Cooper and have put together my first app, a text analyzer. However, whilst I understand all of the concepts and the way in which they work, I can’t for the life of me understand how the app knows to select the middle third of sentences sorted by length from this line:

ideal_sentances = sentences_sorted.slice(one_third, one_third + 1)

I have included the whole app for context any help is much appreciated as so far everything is making sense.

#analyzer.rb --Text Analyzer

stopwords = %w{the a by on for of are with just but and to the my I has some in do}
lines = File.readlines(ARGV[0]) 
line_count = lines.size 
text = lines.join 

#Count the characters
character_count = text.length 
character_count_nospaces = text.gsub(/\s+/, '').length

#Count the words, sentances, and paragraphs
word_count = text.split.length 
paragraph_count = text.split(/\n\n/).length 
sentence_count = text.split(/\.|\?|!/).length

#Make a list of words in the text that aren't stop words,
#count them, and work out the percentage of non-stop words
#against all words
all_words = text.scan(/\w+/)
good_words = all_words.select {|word| !stopwords.include?(word)}
good_percentage = ((good_words.length.to_f / all_words.length.to_f)*100).to_i

#Summarize the text by cherry picking some choice sentances
sentances = text.gsub(/\s+/, ' ').strip.split(/\.|\?|!/)
sentances_sorted = sentences.sort_by { |sentence| sentance.length }
one_third = sentences_sorted.length / 3
ideal_sentances = sentences_sorted.slice(one_third, one_third + 1)
ideal_sentances = ideal_sentences.select{ |sentence| sentence =~ /is|are/ }

#Give analysis back to user

puts "#{line_count} lines" 
puts "#{character_count} characters" 
puts "#{character_count_nospaces} characters excluding spaces" 
puts "#{word_count} words" 
puts "#{paragraph_count} paragraphs" 
puts "#{sentence_count} sentences" 
puts "#{sentence_count / paragraph_count} sentences per paragraph (average)" 
puts "#{word_count / sentence_count} words per sentence (average)"
puts "#{good_percentage}% of words are non-fluff words"
puts "Summary:\n\n" + ideal_sentences.join(". ")
puts "-- End of analysis."

Obviously I am a beginner so plain English would help enormously, cheers.

Answer 1

sentences is a list of all sentences. sentances_sorted is that list sorted by sentence length, so the middle third will be the sentences with the most average length. slice() grabs that middle third of the list, starting from the position represented by one_third and counting one_third + 1 from that point.

Note that the correct spelling is ‘sentence’ and not ‘sentance’. I mention this only because you have some code errors that result from spelling it inconsistently.