Section 7.25. Conclusion

7.24. Dividing a Month into Weeks

Imagine that you wanted to divide a month into weeksfor example, to print a calendar. The following code does that. The array returned is made up of subarrays, each of size seven (7); Sunday corresponds to the first element of each inner array. Leading entries for the first week and trailing entries for the last week may be nil.

def calendar(month,year)   days = month_days(month,year)   t = Time.mktime(year,month,1)   first = t.wday   list = *1..days   weeks = [[]]   week1 = 7 - first   week1.times { weeks[0] << list.shift }   nweeks = list.size/7 + 1   nweeks.times do |i|     weeks[i+1] ||= []     7.times do       break if list.empty?       weeks[i+1] << list.shift     end   end   pad_first = 7-weeks[0].size   pad_first.times { weeks[0].unshift(nil) }   pad_last = 7-weeks[0].size   pad_last.times { weeks[-1].unshift(nil) }   weeks end arr = calendar(12,2008)    # [[nil, 1, 2, 3, 4, 5, 6],                            #  [7, 8, 9, 10, 11, 12, 13],                            #  [14, 15, 16, 17, 18, 19, 20],                            #  [21, 22, 23, 24, 25, 26, 27],                            #  [28, 29, 30, 31, nil, nil, nil]]

To illustrate it a little better, the following method prints out this array of arrays:

def print_calendar(month,year)   weeks = calendar(month,year)   weeks.each do |wk|     wk.each do |d|       item = d.nil? ? " "*4 : " %2d " % d       print item     end     puts   end   puts end # Output: #       1   2   3   4   5   6 #   7   8   9  10  11  12  13 #  14  15  16  17  18  19  20 #  21  22  23  24  25  26  27 #  28  29  30  31