How to add several values to the same key [closed]

Question

how can I add several values to the same key? Something like this:

x = {}
x["k1"] =  nil
x["k1"] << {"a" => "a"}
x["k1"] << {"b" => "b"}

well, this doesn't work like with array.

Answer 1

You can do as below :

For Array as value to the key of a Hash :

h = Hash.new{|hsh,key| hsh[key] = [] }
h['k1'].push 'a'
h['k1'].push 'b'
p h # >> {"k1"=>["a", "b"]}

For Hash as value to the key of a Hash :

h = Hash.new{|hsh,key| hsh[key] = {} }
h['k1'].store 'a',1
h['k1'].store 'b',1
p h # >> {"k1"=>{"a"=>1, "b"=>1}}

Answer 2

Depends on just what you're trying to accomplish here. If you want a hash of arrays, that's easy enough:

x = {}
x['k1'] = Array.new
x['k1'] << 'a'
x['k1'] << 'b'

or if you want nested hashes, simple enough as well

x = {}
x['k1'] = {}
x['k1']['a'] = 'a'
x['k1']['b'] = 'b'

the values in a hash are just objects. They can be arrays, other hashes, or whatever else you might want.

Answer 3

So, you want the value of key 'k1' to be a hash, and you want to add key/value pairs to that hash. You can do it like this:

2.0.0-p195 :111 > x = {}
 => {} 
2.0.0-p195 :112 > x['k1'] = { 'a' => '1' }
 => {"a"=>"1"} 
2.0.0-p195 :117 > x['k1'].merge!({ 'b' => '2' })
 => {"a"=>"1", "b"=>"2"} 

Or, you can do it like this:

2.0.0-p195 :119 > x['k1']['c'] = 3
 => 3 
2.0.0-p195 :120 > x['k1']
 => {"a"=>"1", "b"=>"2", "c"=>3}