ruby - iterate through a hash containing key/array value pairs, and iterate through each value

Question

I have an hash that looks like this:

{
  "key1": [
     "value1",
     "value2",
     "value3"
  ],
  "key2": [
     "value1",
     "value2",
     "value3",
     "value4",
     "value5"
  ],
  "key3": [
     "value1"
  ],
  "key4": [
     "value1",
     "value2"
  ]
}

How do I iterate through every keyN, while also looping through all the values in that key?

I have an array with all the keys if that helps.

Thanks

Possible duplicate of [How to iterate over a hash in Ruby?](http://stackoverflow.com/questions/1227571/how-to-iterate-over-a-hash-in-ruby) — Hamms, Apr 26 '16 at 01:16

score 15 · Accepted Answer · answered Apr 26 '16 at 01:09

15

Pretty simple, really:

hash.each do |name, values|
  values.each do |value|
    # ...
  end
end

You can do whatever you want with name and value at the lowest level.

answered Apr 26 '16 at 01:09

tadman

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indeed simple - was looking at it the wrong way. thanks – user6127511 Apr 26 '16 at 01:47
1

Once you get the hang of it, you'll find this pattern works in a variety of situations. `.each` is the backbone of most Ruby applications. – tadman Apr 26 '16 at 02:40

score 4 · Answer 2 · answered Feb 13 '18 at 09:33

4

If you are sure about the size of arrays, simply you can do like this,

ha = {:a => [1,2]}

ha.each do |k, (v1, v2)|
   p k
   p v1
   p v2
end

Output
:a
1
2

answered Feb 13 '18 at 09:33

YasirAzgar

1,385
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15

score 2 · Answer 3 · answered Apr 26 '16 at 01:15

2

You can do it like this:

hash.each do |key, array|
  array.each do |value|
    # do something
  end
end

answered Apr 26 '16 at 01:15

Sheharyar

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Dharmesh Rupani · Answer 4 · 2016-04-26T02:52:21.943

1

hash.each do |key_N, values_N|
  values_N.each so |values|
  .
  .
  #YourCode
  .
  .
  end
end

edited Apr 26 '16 at 02:52

answered Apr 26 '16 at 01:39

Dharmesh Rupani

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Names like `keyN` should be `key_n` to follow Ruby convention. Capital letters have significant meaning, especially when it comes to `CONSTANT_NAMES` and `ClassNames`. – tadman Apr 26 '16 at 02:41
@tadman Thank you for pointing that out. I have updated my answer. – Dharmesh Rupani Apr 26 '16 at 02:53
Getting there. Generally capitals are avoided entirely in variable names, it just confuses things. – tadman Apr 26 '16 at 02:54
Not `so` but `do`. – Lukas Baliak Apr 26 '16 at 08:29

ruby - iterate through a hash containing key/array value pairs, and iterate through each value

4 Answers4