Combining (ALL individual) Elements of an Arrays in a Dictionary-CodePudding

The Dictionary is defined as

var weekActualPowerZoneTimes: [String:[Int]]()

weekActualPowerZoneTimes:
[
"Ride"  : [1, 1, 1, 1, 1, 1, 1, 1], 
"Run"   : [1, 1, 1, 1, 1, 1, 1, 1], 
"Swim"  : [1, 1, 1, 1, 1, 1, 1, 1], 
"Other" : [1, 1, 1, 1, 1, 1, 1, 1]
]

Goal: combine these arrays to become one. Namely, I'm looking for this output

[4, 4, 4, 4, 4, 4, 4, 4]

The Arrays to be sum, technically should be of equal size, but there could be a chance that they would not be depending on user preference. (Some user may choose to have 7 Power Zones, some may use 5 in the future)

I am currently able to sum 2 arrays using this

let arrayResult:[Int] = zip(array1,array2).map( )

but getting stuck on how to sum a possible arbitrary number of arrays (eg: User may only be doing Run/Swim or Run/Swim/Ride or Others/Swim) in the dictionary.

Update: I tried this, which works, but only if I define the initial "combined" Array

var combined = [0,0,0,0,0,0,0,0]

let aa =
[
"Ride"  : [1, 1, 1, 1, 1, 1, 1, 1],
"Run"   : [2, 1, 1, 1, 1, 1, 1, 1],
"Swim"  : [3, 1, 1, 1, 1, 1, 1, 1],
"Other" : [4, 1, 1, 1, 1, 1, 1, 1]
]

for (index,values) in aa.values.enumerated(){
    print(index, values)
    combined = zip(combined,values).map( )
    print("\(combined)") // [10, 4, 4, 4, 4, 4, 4, 4]
}

But it will result in [] if the initial combined array is defined as

var combined = [Int]()

CodePudding user response：

I found this variant of zipping on reddit that works for arrays of different length

func add(a: [Int], b: [Int]) -> [Int] {
    zip(a, b).map( )   (a.count < b.count ? b[a.count ..< b.count] : a[b.count ..< a.count])
}

So with that we can loop over the values of the dictionary

var combined = [Int]()
weekActualPowerZoneTimes.values.forEach {
    combined = add(a: combined, b: $0)
}

Using a forEach loop over values means we can have any number of values and the add function means the values arrays can be of different length

CodePudding user response：

The logic becomes clear to me in basic loops. Verbose but still.

var combine = [Int]()
for (_, powerzone) in weekActualPowerZoneTimes { 
   for i in powerzone.indices {
      if combine.endIndex > i {
         combine[i]  = array[i]
      } else {
         combine[i] = array[i]
      }
   }
}