Converting PHP array manipulation to Ruby hashes - php

Question

I've written this script to be run in PHP, and am trying to convert it to Ruby.
Code:
$cases = array();
foreach($results as $result)
{
if(!array_key_exists($result['id'], $cases))
$cases[$result['id']] = array($result);
else
$cases[$result['id']][] = $result;
}
foreach($cases as $key => $case)
{
foreach($case as $payment)
{
if(count($case) > 1)
{
$cases[$key]['total'] += ($payment['p1'] > $payment['p2']) ? $payment['p1'] : $payment['p2'];
} else {
$cases[$key]['total'] = ($payment['p1'] > $payment['p2']) ? $payment['p1'] : $payment['p2'];
}
}
}
In Ruby, I have the results as an array returned by MySQL (using mysql2 gem). Using the loop below, it prints every row. How can I check if the key exists when it does not provide keys?
What's the best way to implement this code in Ruby? How can I add a hash onto a hash in Ruby similar to adding an array onto an array in PHP.
results.each(:as => :array) do |row|
puts row.inspect
end
More explanation:
PHP Structure
Array(
0 => Array(
Array(
[id] => 'random id',
[p1] => 534,
[p2] => 105
),
Array(
[id] => 'random id',
[p1] => 335,
[p2] => 425
)
),
1 => Array(
Array(
[id] => 'random id',
[p1] => 259,
[p2] => 124
)
)
)
And i'm trying to iterate over each array inside the first, and if p1 > p2, add p1 to the total key on that array. i.e., the 0 index would look like this:
0 => Array(
'total' => 959,
Array(
[id] => 'random id',
[p1] => 534,
[p2] => 105
),
Array(
[id] => 'random id',
[p1] => 335,
[p2] => 425
)
)

Answer 1

Are you trying to group by result['id']? I believe that "translating" your PHP code to ruby will look something like this:
cases = {}
results.each do |result|
if cases[result['id']]
cases[result['id']] << result
else
cases[result['id']] = [result]
end
end
Another way to get the same result is to use group_by:
cases = results.group_by { |result| result['id'] }
The second part "translated" to ruby will look something like this:
cases.each do |key, c|
c.each do |payment|
if c.count > 1
c['total'] += (payment['p1'] > payment['p2']) ? payment['p1'] : payment['p2']
else
c['total'] = (payment['p1'] > payment['p2']) ? payment['p1'] : payment['p2']
end
end
end
(this will actually not work in ruby, since an array cannot have an arbitrary key like 'total' - it accepts only numbers in its brackets. You will have to modify this code to hold the totals in a different structure)
Again, a more idiomatic way of summing up the max between 'p1' and 'p2' of each payment in each case might look more like this:
totals = cases.values.map do |c|
c.inject(0) { |sum, payment| sum + [payment['p1'], payment['p2']].max }
end