更新 ruby 中特定键的值

Question

I am a fresher in ruby language. Help me to this

I have a map, containing 4 keys. Initial state the value of all keys are zero like below

data_source_map = = Hash.new
data_source_map.store("ab",0)
data_source_map.store("cde",0)
data_source_map.store("fgh",0)
data_source_map.store("jik",0)

I have a while loop, iterating a files from a specific location

while (file = queue.deq)
  begin
    cat = 'cat'
    
    if file.split('.').last=='gz' || file.split('.').last=='zip'
      cat = 'zcat'
    end
            
    user_ids.each do |user|
      res = run_command4("aws s3 cp #{file} - | #{cat} | grep #{user} | wc -l",true,'s3cmd stream failed')
      output = "#{user},#{file.split('/')[-1]},#{file.split('/')[-2]},#{res[:output][0]}"
              
      if "ab".eql?(file.split('/')[-2])
        data_source ="ab"         
      elsif  "cde".eql?(file.split('/')[-2])
        data_source ="cde"
      elsif "fgh".eql?(file.split('/')[-2])
        data_source ="fgh"
      elsif "jik".eql?(file.split('/')[-2])
        data_source ="jik"
      else
        data_source ="NA"
      end
    end
  end
end

{res[:output][0] is a number with respect to the keys.Each file having these keys and an integer number.

Each iteration i need to update the integer value of a given key. how to do this in ruby. am trying to create consolidated report like below

|ab  |200
|cde |4000
|fgh |0

Answer 1

I suggest using a Hash with a default value so you don't need to initialize all possible keys before you start, but that is not required.

data_source_map = Hash.new(0)

To update a value in a hash, you just need to set the new updated value to the hash, it will overwrite the old value.

data_source_map[data_source] = data_source_map[data_source] + 1

This takes the current value from the hash and adds 1 to it, then stores it back into the Hash. Though this is a very common operation, so there is a shorthand for it as well.

data_source_map[data_source] += 1