class Hesh

Gets the counts of items from a list by using a function

@param list [Array]

List of items

@param &fn [Proc]

Function to count by, identity if not provided

@return [Hash[Any, Integer]]

Counts

# File lib/hesh.rb, line 58
def count_from(list, &fn)
  fn ||= IDENTITY_FN
  list.each_with_object(Hash.new(0)) { |v, h| h[fn[v]] += 1 }
end

Inverts the relationship of a hash of arrays

@param hash [Hash[Any, Array]]

Hash with a value pointing to a collection to invert

@example

numbers_to_letters = { 1 => %w(a b), 2 => %w(b c), 3 => %w(a c) }
Hesh.invert_relation(numbers_to_letters)
=> { "a" => [1, 3], "b" => [1, 2], "c" => [2, 3] }

@return [Hash[Any, Array]]

Inverted relation

# File lib/hesh.rb, line 75
def invert_relation(hash)
  hash.each_with_object(Hesh.of_array) { |(k, vs), h|
    vs.each { |v| h[v] << k }
  }
end

Merges a series of hashes infintely deep with a function

@param *hashes [Array]

Collection of hashes

@param &fn [Proc]

Function for joining values, defaults to preferring newest value

@return [Hash[Any, Any]]

Joined hash

# File lib/hesh.rb, line 124
def merge_deep(*hashes, &fn)
  fn ||= PREFER_NEW_FN

  hashes.reduce({}, &merges { |k, o, n|
    o.is_a?(Hash) ? merge_deep(o, n, &fn) : fn[k, o, n]
  })
end

Merges a series of hashes and joins their values

@param *hashes [Array]

Collection of hashes

@return [Hash[Any, Array]]

Joined hash

# File lib/hesh.rb, line 99
def merge_join(*hashes)
  hashes.reduce(Hesh.of_array, &merges { |k, o, n| o + n })
end

Merges a series of hashes and sums their values

@param *hashes [Array]

Collection of hashes

@return [Hash[Any, Integer]]

Summed hash

# File lib/hesh.rb, line 88
def merge_sum(*hashes)
  hashes.reduce(Hash.new(0), &merges { |k, o, n| o + n })
end

Merges a series of hashes with a function

@param *hashes [Array]

Collection of hashes

@return [Hash[Any, Any]]

Merged hash

# File lib/hesh.rb, line 110
def merge_with(*hashes, &fn)
  hashes.reduce({}, &merges(&fn))
end

Creates a Hash of something, I'm not sure what, you tell me!

@param &fn [Proc]

Function for default value of the hash, yielding the hash and
key if ya need them

@return [Hash[Any, Any]]

# File lib/hesh.rb, line 23
def of(&fn)
  Hash.new { |h, k| h[k] = fn.call(h, k) }
end

Creates a Hash of arrays

@return [Hash[Any, Array]]

# File lib/hesh.rb, line 30
def of_array
  Hash.new { |h, k| h[k] = [] }
end

Creates a Hash of hashes

@return [Hash[Any, Hash]]

# File lib/hesh.rb, line 37
def of_hash
  Hash.new { |h, k| h[k] = {} }
end

Creates an infinite hash

@return [Hash[Any, Hash]]

# File lib/hesh.rb, line 44
def of_infinite_hash
  Hash.new { |h, k| h[k] = Hash.new(&h.default_proc) }
end