Can someone explain/annotate this Ruby snippet with comments? - ruby

Question

Please explain this Ruby code so I can convert it to PHP:
data = Hash.new({})
mysql_results.each { |r| data[r['year']][r['week']] = r['count'] }
(year_low..year_high).each do |year|
(1..52).each do |week|
puts "#{year} #{week} #{data[year][week]}"
end
end

Answer 1

data = Hash.new({})
# create hash 'data'
mysql_results.each { |r| data[r['year']][r['week']] = r['count'] }
# maps each row from sql query to hash like this: data[2010][30] = 23
# So you can access 'count' from every year and week in very simple way
(year_low..year_high).each do |year|
# for (year = year_low; year <= year_high; year++)
(1..52).each do |week|
# for (week = 1; week <=52; week++)
puts "#{year} #{week} #{data[year][week]}"
# printf("%d %d %d\n", year, week, data[year][week]);
end
end
Sorry for mixing C with pseudo code, but I hope it helps!

Answer 2

The first bit is just forming an array like so:
$data[2009][17] = 10;
PHP equivalent of that would be:
foreach ($mysql_results as $r){
$data[$r['year']][$r['week']] = $r['count'];
}
The second part would equate to the following:
foreach(range($year_low, $year_high) as $year){
foreach(range(1, 52) as $week){
print $year.' '.$week.' '.$data[$year][$week]
}
}
Hope that helps :)

Answer 3

$data = array();
#Build an array of 'count' per year/week
foreach($mysql_results as $r) {
$data[$r['year']][$r['week']] = $r['count'];
}
#Loop through the $data variable, printing out the 'count' for each year in the array,
#and all 52 weeks that year
for($year = $year_min; $year <= $year_max; $year++) {
for($week=1; $week<=52; $week++) {
echo "$year $week {$data[$year][$week]}";
}
}
Note that year_low and year_high are variables undefined in the current snippet, but they should be known to you.
Also, $mysql_results should be an array containing all rows returned by the database.
In short, the following code does this:
Make an array grouped per year, then per week, containing the value 'count'
Loop through this array, displaying, in order, the year, the week, and the value for 'count', if any