Using Ruby, Reading a File, Containing Name/Value Pairs into a Hash

How to put elements of a file into a hash? -Ruby

hash[key] = value to add a new key-value pair. hash.update(otherhash) to add the key-value-pairs from otherhash to hash.

If you do hash = foo, you reassign hash, losing the old contents.

So for your case, you can do:

hash = {}
File.open(file_path) do |fp|
  fp.each do |line|
    key, value = line.chomp.split("\t")
    hash[key] = value
  end
end

Read file into hash with 2 values per key?

I suppose this is the expected result:

File.readlines('/tmp/blah.cfg').map do |line|
  line.split(',', 2).map(&:strip)
end.to_h
#⇒ {"server1"=>"jim, 22", "server2"=>"bob, 44"}

One might also split the rest into an array:

File.readlines('/tmp/blah.cfg').map do |line|
  k, *v = line.split(',').map(&:strip)
  [k, v]
end.to_h
#⇒ {"server1"=>["jim", "22"], "server2"=>["bob", "44"]}

Read file into hash with 2 values per key?

I suppose this is the expected result:

File.readlines('/tmp/blah.cfg').map do |line|
  line.split(',', 2).map(&:strip)
end.to_h
#⇒ {"server1"=>"jim, 22", "server2"=>"bob, 44"}

One might also split the rest into an array:

File.readlines('/tmp/blah.cfg').map do |line|
  k, *v = line.split(',').map(&:strip)
  [k, v]
end.to_h
#⇒ {"server1"=>["jim", "22"], "server2"=>["bob", "44"]}

How to return a hash containing an array of file names for each owner name?

Here you want to iterate over the file hash and for each key value pair you need to check if it already exists in your new hash, then you just want to add the file name to the array or you create a new key value pair.

def change_hash(file_hash)
  new_hash = {}
  file_hash.each do |file_name, person|
    if new_hash[person]
      new_hash[person] << file_name
    else
      new_hash[person] = [file_name]
    end
  end
  new_hash
end

If you struggle with this, you want to look on how you can manipulate hashes (and arrays) in Ruby. Let me know if you have any more questions.

Reading text file, parsing it, and storing it into a hash. How?

No reason for anything this simple to look ugly!

h = {}
lines.each_with_index do |line, i|
  quantity, item, price = line.match(/^(\d+) (.*) at (\d+\.\d+)$/).captures
  h[i+1] = {quantity: quantity.to_i, item: item, price: price.to_f}
end

Parsing a .txt file to key/value pairs in Ruby

You can do

array = []
# open the file in read mode. With block version you don'r need to
# worry about to close the file by hand. It will be closed when the
# read operation will be completed.
File.open('path/to/file', 'r') do |file|
  # each_line gives an Enumerator object. On which I'm calling
  # each_slice to take 2 lines at a time, where first line is the
  # question, and the second one is the answer. 
  file.each_line.each_slice(2).do |question, answer|
    array << {'Question' => question, 'Answer' => answer}
  end
end

Get key value pair of hash for the given key , in ruby

There is a method, Hash#assoc can do similar things. But it returns the key and value in an array, which you can easily change it into a hash.
And an alternative is use Hash#select, which does return a hash according to the block given.

h1 = { "fish" => "aquatic animal", "tiger" => "big cat" }
h1.assoc "fish"                       # ["fish", "aquatic animal"]
h1.select { |k,v| k == "fish" }       # {"fish"=>"aquatic animal"}

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