Useful Ruby Collection Methods

useful-ruby-collection-methods.md

Useful Enumerable methods (can be called on Hash objects and Array objects):

• all?
• any?
• count
• each_slice
• each_with_index
• each_with_object
• find
• find_all
• find_index
• include?
• map
• max
• min
• none?
• reduce
• reject
• select
• sort
• sort_by
• to_a
• to_h
• zip

Useful Enumerator methods

• with_index
• with_object

Note: Enumerator methods can be chained to any Enumerable method that returns an Enumerator object. For example: Enumerable method select, if it is not passed a block, returns an Enumerator object, so we can chain with_index onto select, like this:

["hello", "goodbye", "hello again"].select.with_index do |str, index|
  index.even? && str.length > 5
end
# => ["hello again"]

#Useful Array methods

• <<
• ==
• []
• []=
• any?
• compact
• compact!
• count
• delete
• delete_at
• delete_if
• dig
• each
• empty?
• find_index
• first
• flatten
• flatten!
• include?
• index
• join
• length
• map
• map!
• permutation
• pop
• push
• reject
• reject!
• reverse
• reverse!
• rotate
• rotate!
• sample
• select
• select!
• shift
• shuffle
• shuffle!
• slice
• slice!
• sort
• sort!
• sort_by!
• transpose
• uniq
• uniq!
• unshift
• zip

Useful Hash methods:

• ::[]
• ::new
• []
• []=
• delete
• delete_if
• dig
• each
• each_key
• each_pair
• each_value
• fetch
• has_key?
• has_value?
• include?
• keep_if
• key?
• keys
• member?
• merge
• merge!