Come Correct with Inject and Collect

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May 3, 2012 Tagged: inject enumerable refactoring arrays ruby Comments (View) Come Correct with Inject and Collect Here’s a refactoring example for a simple Ruby math problem using the inject method. The goal is to generate an n by n multiplication matrix. Pretty straightforward. Let’s make a first pass: def multiplication_table(n) results = [] (1..n).each do |row_index| row = [] (1..n).each { |column_index| row << row_index * column_index } results << row end results.each do |row| header = '%-3s ' * row.length puts header % row end end multiplication_table(7) 1 2 3 4 5 6 7 2 4 6 8 10 12 14 3 6 9 12 15 18 21 4 8 12 16 20 24 28 5 10 15 20 25 30 35 6 12 18 24 30 36 42 7 14 21 28 35 42 49 It does the job, but it’s nothing to look at. We can condense using in-line blocks and fancy curly braces, but first let’s try using inject . Quick background: Inject iterates over a set usi...

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