Add element in the array of hash object - ruby

Question

To a hash of arrays of hashes like
{'1' => [{'a' => 'ss', 'b' => 'tt'},
{'a' => 'sdd', 'b' => 'tdd'}],
'2' => [{'a' => 'ffff', 'b' => 'sds'}],
'3' => [{'a' => 'ddd', 'b' => 'ssss'},
{'a' => 'sss', 'b' => 'sssss'}]}
I want to add 'c' => 'xyz' in every hash in the arrays to get
{'1' => [{'a' => 'ss', 'b' => 'tt', 'c' => 'xyz'},
{'a' => 'sdd', 'b' => 'tdd', 'c' => 'xyz'}],
'2' => [{'a' => 'ffff', 'b' => 'sds', 'c' => 'xyz'}],
'3' => [{'a' => 'ddd', 'b' => 'ssss', 'c' => 'xyz'},
{'a' => 'sss', 'b' => 'sssss', 'c' => 'xyz'}]}
How I can I implement this?

Answer 1

my_arrays = {'1' => [{'a' => 'ss', 'b' => 'tt'},
{'a' => 'sdd', 'b' => 'tdd'}],
'2' => [{'a' => 'ffff', 'b' => 'sds'}],
'3' => [{'a' => 'ddd', 'b' => 'ssss'},
{'a' => 'sss', 'b' => 'sssss'}]}
my_arrays.each do |key, value|
value.each do |val|
val.store('c', 'xyz')
end
end

Answer 2

h = {'1' => [{'a' => 'ss', 'b' => 'tt'},
{'a' => 'sdd', 'b' => 'tdd'}],
'2' => [{'a' => 'ffff', 'b' => 'sds'}],
'3' => [{'a' => 'ddd', 'b' => 'ssss'},
{'a' => 'sss', 'b' => 'sssss'}]}
h.values.each do |ary|
ary.each do |inner_hash|
inner_hash['c'] = 'xyz'
end
end
Above solution is very similar to marmeladze's answer, so let me just explain the differences:
We don't need to do anything with the keys of the outer hash. So we can directly use the outer hash's values for iteration and not care about the keys at all.
inner_hash['c'] = 'xyz' uses element assigment syntax instead of calling #store. They do exactly the same.
In a comment to marmeladze's answer, you asked:
can we achieve this by iterating once instead of 2 each loops ?
h.values gives us an array of arrays. (Because it gives the array of values of h and the values of h are arrays.) We can collapse nested arrays with flatten and thus can achieve the same result with only one explicit iteration:
h.values.flatten.each do |inner_hash|
inner_hash['c'] = 'xyz'
end
or, (equivalently) if you prefer it all on one line
h.values.flatten.each { |ih| ih['c'] = 'xyz' }