Find the location(s) of the max value in two result sets within a CSV of survey results

processor.rb

require 'csv'

csv_contents = CSV.read('Data.csv')
# Shift 3 rows of headers to get to the data
csv_contents.shift
csv_contents.shift
csv_contents.shift

set1 = []
set2 = []

csv_contents.each do |row|
    set1 << row[0..12]
    set2 << row[16..28]
end

def write_row(setNumber, row, index, csv_file)
    max = row.map(&:to_i).max
    max_indices = row.each_index.select{|index| row[index] == max.to_s }

    # Output requires offset-by-1 based indexing
    max_indices.map!{|index| index + 1 }

    csv_file << ["#{setNumber}", "#{index + 1}", "#{max}", "#{max_indices.join(' ')}"]
end

CSV.open("Data.csv", "a+") do |csv_file|
    csv_file << []
    csv_file << ['Set', 'Row', 'Max', 'Index']
    set1.each_with_index do |row, index|
        write_row(1, row, index, csv_file)
    end
    set2.each_with_index do |row, index|
        write_row(2, row, index, csv_file)
    end
end