I'm doing the apple playground tutorial and came across this section:
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25],
]
var largest = 0
var largestKind = String()
for (kind, numbers) in interestingNumbers {
println(kind)
for number in numbers {
if number > largest {
largest = number
largestKind = kind
}
}
}
largest
largestKind
The problem is that it is not finding and printing the largest kind. Am I doing something wrong?
The code you posted works perfectly for me. I assume that you are viewing the output in playgrounds. However, playgrounds isn't always perfect. Try print(largestKind) or try adding some random code after that or open a new playground.
Related
Eg: - Array of integers - [3,3,6] to [[1,2,3],[1,2,3],[1,2,3,4,5,6]]
lazy var arrCount = 3
lazy var numberCount = [Int]()
lazy var someArr = [SomeArr]()
for i in 0 ..< self!. arrCount.count {
self?.numberCount.append(self!.arrCount[I].someArr!.count)
}
print(self?.numberCount.count) // now response based on above example prints [3,3,6]
Response [3,3,6] - [[1,2,3],[1,2,3],[1,2,3,4,5,6]]
Thanks in advance.
You could use map method.
var arr = [3, 6];
print(arr.map { Array(1...$0) })
Output
[[1, 2, 3], [1, 2, 3, 4, 5, 6]]
I want to change subscript coordinates in an Array of Arrays [[Int]] in order to be able to address each value in a way similar to a spreadsheet, so assigning values, formulas across cells, etc.
Currently to address each value I need to subscript like table[2][1] = 12 or similar. I would like to subscript like a spreadsheet table[a][2] = 12, so that I can adapt long and complicated formulas in bigger speadsheets to similar tables using the same system used in spreadsheets.
The question is: how to change the subscript system in an efficient way? I send a simplified example to ilustrate the point
class ViewController: UIViewController {
var table = [[0, 1, 2, 3],
[1, 32, 44, 25],
[2, 12, 66, 43],
[3, 3, 4, 5]]
override func viewDidLoad() {
super.viewDidLoad()
print(table[2][1]) // 12
table[1][1] = 100
table[3][3] = table[1][1] * table[3][1] * 10
print(table[3][3])
printArray(table: table, j: 3)
}
// MARK: - Function
func printArray(table: [[Int]], j:Int) {
for i in 0...j {
print(table[i])
}
}
}
The closest solution I found is to use enums, like here:
enum Column:Int {
case a
case b
case c
// and so on
}
extension Array {
subscript(col:Column) -> Element {
get {
return self[col.rawValue]
}
set(newValue) {
self[col.rawValue] = newValue
}
}
}
var table = [[0, 1, 2, 3],
[1, 32, 44, 25],
[2, 12, 66, 43],
[3, 3, 4, 5]]
table[.a][2] = 12
let val = table[.a][2]
print (val)
Nevertheless, there are two little drawbacks:
you first have hard-code all the "column" letters you want to access to the Column enum.
then, something like table[5][.c] and table[.a][.b] will also be allowed - so you could access the rows via letter, not only the columns
I have two arrays for which I am comparing [Int]
let filter = strongAgainstArray.filter{weakAgainstArray.contains($0)}
This returns an array of common values in the 2 arrays. I then want to go through and remove those values from each array, which I'm doing like so
for item in filter {
for var i = 0; i < strongAgainstArray.count; i += 1 {
if item == strongAgainstArray[i] {
strongAgainstArray.removeAtIndex(i)
print("Removing a Strong against index \(item)")
}
}
for var i = 0; i < weakAgainstArray.count; i += 1 {
if item == weakAgainstArray[i] {
weakAgainstArray.removeAtIndex(i)
print("Removing a Weak against index \(item)")
}
}
}
This works fine, but let's say one of my arrays contains two entries for 12 as an example. How do I only remove one of them? As it stands, all entries of 12 are being removed entirely.
EDIT
I'm now comparing my two arrays using
let commonValues = Array(Set(strongAgainstArray).intersect(weakAgainstArray))
and then those commonValues from each array with
cleanStrongAgainstArray = Array(Set(strongAgainstArray).subtract(Set(commonValues)).sort())
cleanWeakAgainstArray = Array(Set(weakAgainstArray).subtract(Set(commonValues)).sort())
This is a much better overall solution, but I'm still eventually running into the same issue, albeit slightly different than before.
In the playground, for example...
let array = [7,7,9]
let test = Array(Set(array))
test comes back containing [7, 9], and I need to keep that extra 7. How do I do that?
If the order of the arrays aren't important then you can easily achieve the whole solution using Sets:
let dirtyArray = [1,4,6,1,56,4,4,66,23,3,3,12]
let dirtyArray1 = [3,1,6,99,54]
let cleanArray = Array(Set(dirtyArray).union(Set(dirtyArray1)))
print (cleanArray)
[12, 54, 23, 4, 6, 66, 99, 56, 1, 3]
If order is important, use NSOrderedSet:
let strongAgainstArray = [1, 2, 3, 4]
let weakAgainstArray = [3, 4, 5, 6]
let result = NSOrderedSet(array: (strongAgainstArray + weakAgainstArray)).array
I have an basic Int array
Array = [8, 9, 8]
How do i sum all of its values progressively so that the end result would look like this
EndResult = [8, 17, 25]
Tried using for and while loops, but to no avail.
NB: Basic array[0] + array[1] advices will not work. I'm looking for something automatic like a loop solution.
Looking forward to your advices.
Thanks!
May be this:
var arr = [8, 9, 8]
for i in 1..<arr.count {
arr[i] += arr[i-1]
}
print(arr)
Probably there are better ways than this one, but it works
var array = [8, 9, 8]
var result = [Int]()
for i in 0..<array.count{
var temp = 0;
for j in 0...i{
temp+=array[j]
}
result.append(temp)
}
print(result) //[8, 17, 25]
You could use a reduce function in Swift to accomplish this. Note that you can't really do it with map, because you would need to know what the previous call to the map function returned, keep state in a variable outside the map function (which seems dirty), or loop over your array for every map function call.
let array = [8, 9, 8]
let results = array.reduce((0, []), combine: { (reduction: (lastValue: Int, values: Array<Int>), value: Int) in
let newValue = reduction.lastValue + value
return (newValue, reduction.values + [newValue])
}).1
I have an array of arrays called Lines
Numbers = [[1,2,3],[4,5,6],[7,8,9]]
and var numberInt = 10
how do i append this numberInt inside the last array of the multidimensional array? so it would look like
Numbers = [[1,2,3],[4,5,6],[7,8,9,10]]
Thank you.
Use Numbers[Numbers.count - 1] to get last one-dimensional array and append method to add item:
Numbers[Numbers.count - 1].append(numberInt)
print(Numbers) // prints "[[1, 2, 3], [4, 5, 6], [7, 8, 9, 10]]"
I'd also recommend you to take a look at this answer: https://stackoverflow.com/a/25128237/1796907