My case is create multiple choice questions, and i want to compare array in the same index
Correct answer:
[3, 2, 0, 2, 2]
User answer:
[3, 2, 3, 1, 1]
The expected output:
[3,2]
And this is the code
let filteredArray = correctAnswer.filter{ userAnswer.contains($0) }
print(filteredArray)
But the output:
[3, 2, 2, 2]
Thank you.
If you want to compare two array index by index then you can use compactMap with zip.
let correctAns = [3, 2, 0, 2, 2]
let userAns = [3, 2, 3, 1, 1]
let finalAns = zip(correctAns, userAns).compactMap({ $0 == $1 ? $0 : nil })
print(finalAns) // [3, 2]
Edit: You can even simplified this by using @MartinR suggestion.
let finalAns = zip(correctAns, userAns).filter(==).map { $1 }
If you want index of correct answer than you can get like this.
let finalAnsIndex = zip(correctAns, userAns).enumerated().compactMap({ $0.element.0 == $0.element.1 ? $0.offset : nil })
print(finalAnsIndex) // [0, 1]
let matches = zip(correct,user).filter({$0 == $1 }).map{$1}
.filter(==).map { $1 }
compactMap{$0.element.0 == $0.element.1 ? $0.offset : nil}You can zip the two arrays to filter the answers that was correct:
zip(userGuesses, correctAnswers).filter { (guess, answer) in guess == answer }
Further, if you want only the right answers you can map the zipped sequence to get only the users answers:
zip(userGuesses, correctAnswers)
.filter { (guess, answer) in guess == answer }
.map { (guess, _) in guess }
That said, this doesn't say which questions was answered correctly. For example: If the correct answers were [1,2,3,2,1,3] and the user answered [1,3,1,2,3,3] it wouldn't be possible to know which questions the user got right (since both #1, #3, #1, #6, and #5, #6, all result in [1,3]
