Group from Array to Dictionary

Question

I have class:

class DisplayTime {

    var time: Schedules

    init (time: Schedules){
        self.time = time

    }
}

Schedules - class with next properties:

class Schedules: Object {
    dynamic var hour = 0
    dynamic var minute = 0
    dynamic var groupIndex = 0

}

So, I'd like to get Dictionary, where key - hour, and value - array of Schedules - var dictTime: [Int:[Schedules]]

I try, but unsuccessfully:

func groupBy() -> [Int:[Schedules]]{

        let displayTime = self.displayTimes

        var dictTime: [Int:[Schedules]] = [:]


        for i in 0..<displayTime.count {

            dictTime[displayTime[i].time.hour] = [displayTime[i].time]
        }

       print (dictTime)

      return dictTime

    }

I understand - that function created only [key:[one_value]], but I may have several values for one key, how to handle that variant? (if key_now repeat key_before -> add to array Schedules for key_now to key_before.

See [How to group by the elements of an array in Swift](http://stackoverflow.com/q/31220002/2976878) — Hamish, Jan 09 '17 at 11:55
@Hamish, yes, I saw it, but i can't use that example in my function(( — Vadim Nikolaev, Jan 09 '17 at 11:58

score 2 · Accepted Answer · edited May 23 '17 at 11:45

2

Using the categorise(_:) method from the extension shown in this answer, you can simply say:

let dictTime = displayTimes.lazy.map{$0.time}.categorise{$0.hour}

map(_:) is used in order to iterate over the time of each DisplayTime and lazy is used in order to prevent the creation of an intermediate array.

edited May 23 '17 at 11:45

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answered Jan 09 '17 at 12:40

Hamish

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Group from Array to Dictionary

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