Array manipulation tricks in Ruby

Let's say we have an array and we do not want the first element of the array. Ruby provides a method Array#drop which removes the elements from the array and returns the result.

>> args = [1,2,3,4]
=> [1, 2, 3, 4]
>> args.drop(1)
=> [2, 3, 4]

Good thing about this method is that it does not manipulate the original array.

>> args = [1,2,3,4]
=> [1, 2, 3, 4]
>> args.drop(1)
=> [2, 3, 4]
>> args
=> [1, 2, 3, 4]

If we don't want first two elements of the array, we can pass two as the argument to drop.

>> args = [1,2,3,4]
=> [1, 2, 3, 4]
>> args.drop(2)
=> [3, 4]

Ruby also has a method Array#drop_while which drops elements up to, but not including the first element for which the predicate returns false or nil.

>> args
=> [1, 2, 3, 4]
>> args.drop_while { |a| a < 3 }
=> [3, 4]
>>

This method is useful when you know for certain that you don't want certain elements from the start of the array.

Ruby also has Array#take and Array#take_while which return the elements from the start based on the argument.

>> args
=> [1, 2, 3, 4]
>> args.take_while { |a| a < 3 }
=> [1, 2]
>> args.take(2)
=> [1, 2]

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