Add element in the array of hash object

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?

Have you tried anything, yet?

das-g
– das-g

2015-04-11 19:33:30 +00:00
Commented Apr 11, 2015 at 19:33 — das-g
– das-g, Commented Apr 11, 2015 at 19:33

das-g · Accepted Answer · 2015-04-11 19:57:59Z

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

edited Apr 11, 2015 at 19:57

das-g

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answered Apr 11, 2015 at 19:36

marmeladze

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2 Comments

Deepti Kakade Over a year ago

can we achieve this by iterating once instead of 2 each loops ?

marmeladze Over a year ago

i am a newbie of ruby, so i really don't know, if it is possible or not. but your hash seems having 2 different data type, hash and array - and they are nested. iterating over hashes is first thing to do - to grab the array, then another iteration needed to grab the hash inside the array. for iterating over hash you need key and value, for array just value is sufficient. there is a structural difference between methods - so, it seems impoossible to me now. but let me rewrite again, i'm a newbie.

Community · Accepted Answer · 2017-05-23 12:24:07Z

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' }

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