Trying to build a rating system in Swift and looking for a cleaner way to loop through each of the values.
private func calculateRating(user: String) throws -> String {
let query = try Rating.makeQuery().filter("user", user).all()
var fiveStars = [Int]()
var fourStars = [Int]()
var threeStars = [Int]()
var twoStars = [Int]()
var onestar = [Int]()
if query.count > 1 {
for rating in query {
// Check each value and assign it to its associated value
// insert large if/else condition here :)
}
// Perform calculation and return value below
return ""
} else {
// Only one rating has been set
return query[0].value
}
}
Currently I'm looping through each of the values and assigning the rating to it's associated array fiveStars fourStars etc. I will then calculate the rating by the standard multiplication method. Is there a cleaner way to loop through the ratings and assign it to the relevant fiveStars array etc without creating a long if/else conditional?
Thanks
Edit: Sample output would be a single rounded up value out of 5 i.e. "4" out of five based on 1000's of multiple ratings.
let twoStars: [Int] = query.filter {$0.val == 2} .map {$0.val}
And so on.
Related
OK, I understand that I can not modify the results of a Realm Object.
So what is best way to change the data.
First I get all the Realm data as Results< Month >
let m = Month.getAllEntriesByDateAsc()
Now I need to loop through all the data to modify it. (This is a function to recalculate the entire table data.)
So I want to loop through the data and do something like:
for i in m {
var d = i
// perform calculations like
d.value = 9999
}
I want to do all the modifying on d.
Is these some sort of mapping I can use to create the new edible object from the Realm data?
Previously I did something like this:
for i in m {
let d = Month()
d.value = i.value
d.status = i.status
}
But there are now to many variables.
I guest what I need to so change the Realm Object to the Model object?
And the .toArray() stuff will not work inside the loop? Not sure why.
Thanks.
extension Results {
func toArray<T>(ofType: T.Type) -> [T] {
var array = [T]()
for i in 0 ..< count {
if let result = self[i] as? T {
array.append(result)
}
}
return array
}
}
From here
I have two arrays, one an array of array of profiles and one of the section names:
var sections: [Array<Profile>] = [friends, contacts, other]
var sectionNames = ["Friends", "Contacts", "Other Users"]
How do I filter the names based on whether the sections are empty? I get an error when I try the code below:
sectionNames.filter { index, _ in
sections[index].count > 0
}
Contextual closure type '(String) throws -> Bool' expect 1 argument, but two given
You can use zip and compactMap:
let nonEmptySections = zip(sections, sectionNames).compactMap { $0.isEmpty ? nil : $1 }
Using zip has the advantage that you don't get crashes if the two arrays have different sizes. On the other hand, it can lead to subtle bugs.
I'd recommend that you use a data structure to model you data instead:
struct Section {
let name: String
let profiles: [Profile]
}
This should ease the way you process the sections in your app. And by using #Alexander's suggestion, you can add an isEmpty property to the struct, making it even easier to use
extension Section {
var isEmpty: Bool { return profiles.isEmpty }
}
... later in the code
let nonEmptySections = sections.filter { !$0.isEmpty }
you can try something like this
var ar1:[Array<Int>] = [[1,2],[3,4,],[],[5,6]]
var ar2 = [1,2,3,4]
ar2 = (0 ..< ar1.count).filter {ar1[$0].count > 0}.map {ar2[$0]}
print(ar2) // [1, 2, 4]
class Employee{
var id:Int
var name:String
var salary:Int
init(){
self.id=0
self.name=""
self.salary=0
}
func getInfo(){
self.name=readLine()!
self.id=Int(readLine()!)!
self.salary=Int(readLine()!)!
}
}
var count=0
var flag="y"
var empData:[Employee]=[]
repeat{
count+=1
empData[count]=Employee()
empData[count].getInfo()
flag=readLine()!
}while(flag=="y") `
I have a class Employee with properties id , nam and salary. The function getInfo() is used to get information from user. I want to read data until the flag!="y" . I am getting index out of range error.
What is the right way of inputting data? Can we index the objects ?
You need to append to your array to make it increase in size. Replace
empData[count]=Employee()
with
empData.append(Employee())
to avoid index out of range error
Update
To make your code a little less horrible I would do
repeat {
var employee = Employee()
employee.getInfo()
empData.append(employee)
flag=readLine()!
}while( flag == "y" )
The subscript operator cannot be used to add elements to an array index which doesn't exist yet. You either need to initialize the array with an element count if you know at the time of initialization how many elements your array will have or use the append operator to add new elements to the array after the last index.
You don't even need the count variable, as you can simply access empData.last safely after calling append and adding a new Employee to the Array.
var flag="y"
var empData:[Employee]=[]
repeat {
empData.append(Employee())
empData.last!.getInfo()
flag=readLine()!
} while(flag=="y")
I would advise you to seriously reconsider your implementation as it is really unsafe at the moment. You are not validating user input in any way, hence your getInfo function can easily cause runtime errors if the user input is not in the expected form. Moreover, creating an empty initializer for Employee doesn't make sense, you could simply create a failable initializer, where you read the input and if the input is not of the correct form, make the initializer return nil.
class Employee{
let id:Int
let name:String
let salary:Int
init?(){
guard let name = readLine() else { return nil }
self.name = name
guard let idString = readLine(), let id = Int(idString) else { return nil }
self.id = id
guard let salaryString = readLine(), let salary = Int(salaryString) else { return nil}
self.salary = salary
}
}
var flag="y"
var empData:[Employee]=[]
repeat {
if let employee = Employee() {
empData.append(employee)
} else {
// Display error message to the user
}
flag=readLine() ?? ""
} while(flag=="y")
I am downloading information from a Firebase database and it is being inputted via a for loop into:
static var Reports = [String:[String:String]]()
I need to figure out a way to search the inside values for a certain string
I have messed around with this but can't seem to get it inside the inside dictionary (If that makes sense)
for values in Reports.count {
if let item = Reports["favorite drink"] {
print(item)
}
}
I need to have a search string then a number of times the value appears like so:
func findString(dict Dictionary) -> Int {
var ReportsLevel1 = 0
(for loop I'm guessing)
search here for string
return ReportsLevel1
}
Tip: the outside dictionary keys are not set in stone, they depend on what time and date the report was submitted
To find out the numberOfTimes in which "yourSearchString" appears you can do as follows
var numberOfTimes = 0
for internalDictionary in reports.values
{
for value in internalDictionary.values
{
if (value == "yourSearchString") { numberOfTimes += 1 }
}
}
or
let numberOfTimes = reports.flatMap { internalDictsArray in internalDictsArray.value.filter { $0.value == "yourSearchString" } }.count
Language: Swift
I declared a dictionary whose value is an array, like this:
var unloadedImagesRows = [String:[Int]]()
private func addToUnloadedImagesRow(row: Int, forLocation:String!) {
print("addToUnloadedImagesRow 0: row: \(row)")
var unloadedRows = imagesRowForLocation(forLocation)
unloadedRows!.append(row)
}
private func imagesRowForLocation(location:String!) -> [Int]! {
var unloadedRows = unloadedImagesRows[location];
if unloadedRows == nil {
unloadedRows = [Int]()
unloadedImagesRows[location] = unloadedRows
}
return unloadedRows
}
private func someMethod() {
addToUnloadedImagesRow(rowIndex, forLocation: event.iconImg)
...
}
The "unloadedRows!.append(row)" works and I saw in my debugger works as I saw the count increased to 1.
However, the next time I retrieve the value as in line "var unloadedRows = unloadedImagesRows[location]", I get a result of an array containing 0 values.
How do I implement a dictionary of array values, and assign (ie. append) new values to the array?
var unloadedRows = imagesRowForLocation(forLocation)
unloadedRows!.append(row)
unloadedImagesRows[forLocation] = unloadedRows!
You retrieve the array by value, i.e. another instance of the array stored inside the dictionary gets created. Therefore you should set it back into the dictionary after appending a value