Sort Array based on other Sorted Array

Question

I have two arrays of the same size and I sort the second one. How can I array the first one to match?

Basic example (imagine replacing Ints with Strings):

var array1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0]

var array2 = [5, 2, 3, 4, 5, 6, 8, 5, 4, 5, 1] 

array2.sort = ({ $0 > $1})

Result:

array2 is now [8, 6, 5, 5, 5, 5, 4, 4, 3, 2, 1]

How to sort array1's index value to match array2?

array1 should now be [6, 5, 0, 4, 7, 9, 3, 8, 2, 1, 0]

I would say make one array of object and sort object...

Fahim Parkar
– Fahim Parkar

2015-02-10 07:23:43 +00:00
Commented Feb 10, 2015 at 7:23 — Fahim Parkar
– Fahim Parkar, Commented Feb 10, 2015 at 7:23

rintaro · Accepted Answer · 2015-02-10 09:09:30Z

4

Zip2, sorted and map

array1 = map(sorted(Zip2(array1, array2), {$0.1 > $1.1}), { $0.0 })

Combining filter

var array1 = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0"]
var array2 = [5, 2, 3, 4, 5, 6, 8, 5, 4, 5, 1]

func isEven(x:Int) -> Bool {
    return x % 2 == 0
}

let result = map(sorted(filter(Zip2(array1, array2), { isEven($0.1) }), {$0.1 > $1.1}), { $0.0 })
// -> ["6", "5", "3", "8", "1"]

As you can see, the line is too complex, you might want to Array method chain syntax:

let result2 = Array(Zip2(array1, array2))
    .filter({ isEven($0.1) })
    .sorted({ $0.1 > $1.1 })
    .map({ $0.0 })

Anyway, if your array2 is [PFObject], you can implement the function something like:

func isOpen(restaurant: PFObject, forTime time: String, onDay day: Int) -> Bool {

    // return `true` if the restaurant is open, `false` otherwise

}

edited Feb 10, 2015 at 9:09

answered Feb 10, 2015 at 7:32

rintaro

52k14 gold badges135 silver badges140 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Onichan Over a year ago

Does this work for functions too? If I call a function for array2 filterAreOpen(detailsForFoodPhotos, forTime: time.time, onDay: time.dayOfWeek) and map array1 the same way?

Onichan Over a year ago

Would it look something like this: map(filterAreOpen(detailsForFoodPhotos, forTime: time.time, onDay: time.dayOfWeek), { $0.0 })

rintaro Over a year ago

what is filterAreOpen, maybe this? If so, I don't think it will work. I will add the basic example combining filter.

Onichan Over a year ago

Thank you so much. But will the filter work if my filterAreOpen function returns an array? Or will I need to create a new function that can filter individual data? (please see edited question)

rintaro Over a year ago

The latter: you need to create a new function. It's not so hard, your filterAreOpen already have filter logic. You can extract that.

Collectives™ on Stack Overflow

Sort Array based on other Sorted Array

1 Answer 1

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related