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Demo (I expect result [3]):
[1,2] - [1,2,3] => [] # Hmm [1,2,3] - [1,2] => [3] # I see a = [1,2].to_set => #<Set: {1, 2}> b = [1,2,3].to_set => #<Set: {1, 2, 3}> a - b => #<Set: {}> WTF! And:
[1,2,9] - [1,2,3] => [9] # Hmm. Would like [[9],[3]] How is one to perform a real set difference regardless of order of the inputs?
Ps. As an aside, I need to do this for two 2000-element arrays. Usually, array #1 will have fewer elements than array #2, but this is not guaranteed.
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Array#delete() : delete() is a Array class method which returns the array after deleting the mentioned elements. It can also delete a particular element in the array. Syntax: Array. delete() Parameter: obj - specific element to delete Return: last deleted values from the array.
Using delete_if# method The delete_if method accepts a conditional and removes all the elements in the array that do not meet the specified condition. The method takes a block and evaluates each element for a matching case. If the value does not meet the set conditions, the method removes it.
The pop() function in Ruby is used to pop or remove the last element of the given array and returns the removed elements. Parameters: Elements : This is the number of elements which are to be removed from the end of the given array.
The - operator applied to two arrays a and b gives the relative complement of b in a (items that are in a but not in b).
What you are looking for is the symmetric difference of two sets (the union of both relative complements between the two). This will do the trick:
a = [1, 2, 9] b = [1, 2, 3] a - b | b - a # => [3, 9] If you are operating on Set objects, you may use the overloaded ^ operator:
c = Set[1, 2, 9] d = Set[1, 2, 3] c ^ d # => #<Set: {3, 9}> For extra fun, you could also find the relative complement of the intersection in the union of the two sets:
( a | b ) - ( a & b ) # => #<Set: {3, 9}> If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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