I have an array of hashes called @messages :
[{ "id" => "1", "user_name" => "John", "content" => "xxxxx" },
{ "id" => "2", "user_name" => "John", "content" => "yyyyy" },
{ "id" => "3", "user_name" => "Paul", "content" => "zzzzzz" },
{ "id" => "4", "user_name" => "George", "content" => "xxyyzz" }]
What is the method to count the different values of user_name in @messages (which should give 3 here)?
There is no method to do it, the simplest solution I can think of is using map:
attributes = [{ "id" => "1", "user_name" => "John", "content" => "xxxxx" },
{ "id" => "2", "user_name" => "John", "content" => "yyyyy" },
{ "id" => "3", "user_name" => "Paul", "content" => "zzzzzz" },
{ "id" => "4", "user_name" => "George", "content" => "xxyyzz" }]
count = attributes.map { |hash| hash['user_name'] }.uniq.size
YOu already have your answer, but if you are also interested in the actual number per user_name, you could do
counts = attributes.inject(Hash.new{|h,k|h[k]=0}) { |counts, h| counts[h['user_name']] += 1 ; counts}
Then counts.size tells you how many distinct names there are.
size. Works as well!Another way would be using group_by:
attributes = [{ "id" => "1", "user_name" => "John", "content" => "xxxxx" },
{ "id" => "2", "user_name" => "John", "content" => "yyyyy" },
{ "id" => "3", "user_name" => "Paul", "content" => "zzzzzz" },
{ "id" => "4", "user_name" => "George", "content" => "xxyyzz" }]
attributes.group_by{|hash| hash["user_name"]}.count # => 3