Codecabulary Home / Learn Ruby / Array Methods
Array.at(index) -- Returns value or nil if index DNE
a = [1, 2, 3]
a.at(0)
>> 1
a.at(100)
>> nil
Array.fetch(index) -- Returns value or IndexError if index DNE
a.fetch(100)
>> IndexError
Array.first
a.first
>> 1
Array.last
a.last
>> 3
Array.take(num)
arr = (1..6).to_a
>> [1, 2, 3, 4, 5, 6]
arr.take(3)
>> [1, 2, 3]
arr
>> [1, 2, 3, 4, 5, 6] # Take is non-destructiveArray.drop(num)
arr.drop(3)
>> [4, 5, 6] # Drop is also non-destructive
Array.count
arr.count
>> 6
Array.length
arr.length
>> 6
Array.empty?
arr.empty?
>> false
b = []
b.empty?
>> true
Array.include?
arr.include?(99)
>> true
arr.include?(101)
>> false
b = ['strawberry']
b.include?('strawberry')
>> true
Array.push(value) -- Add value at the end of the array
c = [1, 2, 3]
c.push(4)
>> [1, 2, 3, 4]
Array.pop -- Removes and returns the last element in an array (destructive)
c.pop
>> 4
c
>> [1, 2, 3]
Array.unshift(value) -- Add value at the beginning of the array
c.unshift(0)
>> [0, 1, 2, 3]
Array.shift(value) -- Remove and return the first item (destructive)
c.shift
>> [1, 2, 3]
Array.insert(index, value)
c.insert(1, 'apple')
>> [1, 'apple', 2, 3]
Array.delete_at(index)
c.delete_at(1)
>> [1, 2, 3]
Array.delete(value)
c.delete(1)
>> [2, 3]
Array.compact -- Returns an array without nil values; not in place
arr = ['a', 1, 'b', 2, nil, nil, 3, nil, 'happy']
arr.compact
>> ['a', 1, 'b', 2, 3, 'happy']
arr
>> ['a', 1, 'b', 2, nil, nil, 3, nil, 'happy'] # Compact is not performed in-placeExclamation point performs method in-place
arr.compact!
>> ['a', 1, 'b', 2, 3, 'happy']
arr
>> ['a', 1, 'b', 2, 3, 'happy']
To remove duplicates in an array, there's the non-destructive Array.uniq and the destructive Array.uniq!
a = [1, 1, 2, 3, 3]
a.uniq # Modification not in-place
>> [1, 2, 3]
a
>> [1, 1, 2, 3, 3]
a.uniq! # Performs modification in-place
>> [1, 2, 3]