I am working with arrays and I created a function that appends an array from within. However when I print the array, it still appears empty. What gives?
var queriesFinal : [String] = []
func queryValidator(search : String)
{
var letterSet = NSCharacterSet(charactersInString: "abcdefgjhijklmnopqrstuvwxyz ")
var numberSet = NSCharacterSet(charactersInString: "1234567890".uppercaseString)
var queriesTwo : [String] = search.lowercaseString.componentsSeparatedByCharactersInSet(letterSet)
for(var x = 0; x < queriesTwo.count; x++)
{
for(var y = 0; y < 10; y++)
{
var str = String(y)
if(queriesTwo[x] == str)
{
var numberStr = String(queriesTwo[x]) + "th"
queriesFinal.append(numberStr)
}
}
}
}
println(queriesFinal)
search = "Matt 8th"
queryValidator(search)
This code can run in playground..
I appreciate any help!
As mentioned by Mike S, you've made a small mistake println should be after your queryValidator, I've also added an optional in case your queryValidator search returns nil, also as mentioned by Zaph you don't need numberSet, so I removed it:
func queryValidator(search : String) -> [String]? {
let queriesTwo:[String] = search.lowercaseString.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: "abcdefgjhijklmnopqrstuvwxyz "))
var queriesResult:[String] = []
for x in 0...queriesTwo.count-1 {
for y in 0...9 {
if(queriesTwo[x] == String(y)) {
queriesResult.append(String(queriesTwo[x]) + "th")
}
}
}
return queriesResult.count > 0 ? queriesResult : nil
}
var search = "Matt 8 less7"
if let queriesFinal = queryValidator(search) {
println(queriesFinal)
} else {
println("no result")
}
An alternative approach with Regular Expressions:
func queryValidator(search: String) -> [String] {
var queriesFinal:[String] = []
var nsSearch: NSString = search
let pattern = "(\\d+)"
var regEx = NSRegularExpression(pattern:pattern, options:nil, error:nil)
regEx?.enumerateMatchesInString(nsSearch, options:nil, range:NSMakeRange(0, nsSearch.length), usingBlock: { (result, flags, stop) in
let found = nsSearch.substringWithRange(result.range)
queriesFinal.append("\(found)th")
})
return queriesFinal
}
var result = queryValidator(search)
println("result: \(result)")
Output:
result: [8th, 7th, 6th]
For information on regular expressions see: Regular Expressions
Related
Writing the question and answer from here, I'm curious to know if there is any simpler way to write the following:
var nums = [1,2,3]
let sum1 = nums.reduce([Int]()){
let temp = $0
temp.append($1)
return temp
}
I know I can do:
var nums = [1,2,3]
let sum1 = nums.reduce([Int]()){
return $0 + [$1]
}
But that comes off as a hack.
To explain this better, I want to get closer to the example (from docs) below, just that it should be for an array:
let numbers = [1, 2, 3, 4]
let numberSum = numbers.reduce(0, { x, y in
x + y
})
EDIT:
Since folks asked what was I trying to achieve:
I was doing the leetcode's group Anagram's challenge.
My solution was:
struct WordTraits: Equatable{
let count: Int
let charactersSet: Set<Character>
}
struct Word: Equatable{
let string: String
let wordTraits: WordTraits
}
class Solution{
func groupAnagrams(_ strs: [String]) -> [[String]]{
var words : [Word] = []
var answers : [(traits: WordTraits, words: [Word])] = []
var count = 0
strs.forEach{ str in
count += 1
let count = str.count
let string = str
let characterSet = Set(str)
let wordTraits = WordTraits(count: count, charactersSet: characterSet)
let word = Word(string: string, wordTraits: wordTraits)
words.append(word)
}
while words.count != 0{
let word = words[0]
let traits = word.wordTraits
var isWordAdded = false
for (i, answer) in answers.enumerated(){
if answer.traits == traits{
answers[i].words.append(word)
isWordAdded = true
break
}
}
if !isWordAdded{
answers.append((traits: traits, words:[word]))
}
words.removeFirst()
}
let emptyArray : [[String]] = []
let finalAnswer = answers.reduce(emptyArray, { total, answer in
let strings : [String] = answer.words.reduce([String](), {
return $0 + [$1.string]
})
return total + [strings]
})
return finalAnswer
}
}
let s = Solution()
print(s.groupAnagrams(["ate", "eta", "beta", "abet"])) // [["ate", "eta"], ["beta", "abet"]]
reduce(..) has to know which type it is working with. To infer this it can use the return type or the type of the first argument. So you can also write:
var nums = [1,2,3]
let sum1: [Int] = nums.reduce([]){
return $0 + [$1]
}
[$1] can't be replaced with $1 because +-operator between value and collection is undefined.
Nope. But you can add it:
extension Array {
func appending(_ newElement: Element) -> Array<Element> {
return self + [newElement]
}
func appending(contentsOf sequence: Sequence) -> Array<Element> {
return self + sequence
}
}
Um, how about the + operator?
let nums = [1, 3, 5]
let more = nums + [7]
Your code is trying to convert a complex structure to an array of arrays. You can use map for this.
This should work:
let finalAnswer = answers.map { answer in
answer.words.map {
$0.string
}
}
Edit:
I was able to solve it using minimal code:
class Solution {
func groupAnagrams(_ words: [String]) -> [[String]] {
let processedWords = words.map {
(key: String($0.sorted()), value: $0)
}
return Dictionary(grouping: processedWords, by: { $0.key }).map { groupedValue in
groupedValue.value.map {
$0.value
}
}
}
}
You've greatly overcomplicated your computation of "final answers". It could just be:
return answers.map { $0.words.map { $0.string } }
I have variables of type string, [int], bool
var books:[String] = ["Hobbit","LOTR","Fellowship"]
var chaptersToRead:[[Int]] = [[1],[1,3],[2,3]]
var read:[Bool] = [false,true,true]
I have function display() so that I can see details about all the books individually
func display() -> [[Any]] {
var output = [[Any]]()
for i in 0..<books.count {
output.append([books[i], chaptersToRead[i], read[i]])
}
return output
}
I like to store values of books in two arrays based on condition if chaptersToRead = 1, as follows
var booksAssigned:[String] = ["Hobbit","LOTR"]
var readStatus:[Bool] = [false,true]
I tried to get the above result by doing the following below which is not working. What am I doing wrong?
var booksAssigned:[String] = []
var readStatus:[Bool] = []
for (index, books) in display().enumerated()
{
if chaptersToRead.joined().contains(1)
{
//I am getting signal SIGABRT error here
booksAssigned = books as! [String]
}
}
for (index, status) in display().enumerated()
{
if chaptersToRead.joined().contains(1)
{
//I am getting signal SIGABRT error here
readStatus = status as! [Bool]
}
}
Try this:
var booksAssigned:[String] = []
var readStatus:[Bool] = []
for (index, chapters) in chaptersToRead.enumerated() {
if chapters.contains(1) {
booksAssigned.append(books[index])
readStatus.append(read[index])
}
}
print(booksAssigned)
print(readStatus)
Edit: Edited as per #Nirav D's suggestion.
Remove var keyword from if blocks. You have already declared those variables.
var booksAssigned:[Any] = []
var readStatus:[Any] = []
for (index, books) in display().enumerated()
{
if chaptersToRead.joined().contains(1)
{
booksAssigned = books
}
}
for (index, status) in display().enumerated()
{
if chaptersToRead.joined().contains(1)
{
readStatus = status
}
}
This works.
Here is my code, inside of my for loop, there is a while loop changes
the variable i's value. I printed out the value of i before while loop
and and after loop, the new "before index value" is expected to start
at "after index value +1". However, the "new before index value" just
increase as normal, which increase one each time. Appreciate your time.
class Solution
{
func summaryRange(nums: [Int]) -> [String]
{
var result = [String]()
if nums.count == 1
{
result.append(String(nums[0])+"")
return result
}
for var i in (0...nums.count-1)
{
let a = nums[i]
print("before: \(i)")
while i+1<nums.count && (nums[i+1] - nums[i] == 1)
{
i += 1
}
if a != nums[i]
{
result.append(String(a) + "->" + String(nums[i]))
}
else
{
result.append(String(a)+"")
}
print("after: \(i)")
}
return result
}
}
var test = Solution()
var input = [0,1,2,4,5,7]
var result = test.summaryRange(input)
print(result)
This code tries to get result like ["0->2","4->5","7"]
This is my own solution. I figure out the problem. Basically, I switch
the "for loop" to a "while loop". Then, it works.
class Solution
{
func summaryRanges(nums: [Int]) -> [String]
{
var result = [String]()
var i = 0
while(i<nums.count)
{
let a = nums[i]
while i+1<nums.count && (nums[i+1] - nums[i] == 1)
{
i += 1
}
if a != nums[i]
{
result.append(String(a) + "->" + String(nums[i]))
}
else
{
result.append(String(a)+"")
}
i += 1
}
return result
}
}
In swift, for in loop is a wrapper around the Sequence Type. In this particular case, 0...numCount-1 is a Sequence of Ints. When you call for in this is what happens internally.
let a = 0..<5
var generator = a.generate()
while var i = generator.next() {
print(i + 1)
i+= 1
}
So even if you increment the value of i inside the loop, it wont affect the loop itself. This is because loop is controller only by calling genertator.next().
This helps understand the basics.
This was an interesting one. I think this does the trick (with some code cleanup as well :-]
class Solution
{
func summaryRange(nums: [Int]) -> [String] {
var result = [String]()
var currentRange = [Int]()
for num in nums {
if currentRange.isEmpty { //if range is empty, start a new range
currentRange.append(num)
continue
}
if num - 1 != currentRange.last! { //if not next number in sequence, close range, start new
result.append(closeRange(currentRange))
currentRange = []
currentRange.append(num)
} else if num - 1 == currentRange.last {
currentRange.append(num) //if next number, add to range
}
}
if !currentRange.isEmpty {
result.append(closeRange(currentRange)) //check for unclosed ranges
}
return result
}
func closeRange(range: [Int]) -> String {
guard range.count > 0 else { return "" }
if range.count == 1 { return String(range.first!) }
return "\(range.first!)->\(range.last!)"
}
}
var test = Solution()
var input = [0,1,2,4,5,7]
var result = test.summaryRange(input)
print(result)
Let me know how this works for you!
This question already has an answer here:
Swift: sorting of array is not done correctly
(1 answer)
Closed 7 years ago.
I have an Array containing values like 7-4.json, 87-1.json and 102-4.json and want to sort it (ascending). I used the following code:
var fileNames = ["7-4.json", "87-1.json", "102-4.json"]
fileNames = fileNames.sort{ $0 < $1 }
print(fileNames)
which results in:
["102-4.json", "7-4.json", "87-1.json"]
So it didn't worked as I aspected. How can I sort it like 7-4, 87-1, 102-4?
Here you go:
var fileNames = ["7-4.json", "87-1.json", "102-4.json"]
func sortWithCustomFormat(first: String, second: String) -> Bool{
func extract(value: String) -> (Int, Int){
return (Int(value.componentsSeparatedByString("-").first!)!, Int(value.componentsSeparatedByString("-").last!.componentsSeparatedByString(".").first!)!)
}
let firstNumber = extract(first)
let secondNumber = extract(second)
if firstNumber.0 != secondNumber.0 { return firstNumber.0 < secondNumber.0 }
return firstNumber.1 < secondNumber.1
}
fileNames.sort(sortWithCustomFormat)
The function sortWithCustomFormat has a function extract that takes the inputted string and extracts the first and second numbers from it. Then, you compare the first numbers. If they are equal, then you compare the second numbers.
var fileNames = ["87-1.json", "7-4.json", "87-3.json", "102-4.json"]
fileNames = fileNames.sort({ (s1, s2) -> Bool in
let f1 = s1.stringByReplacingOccurrencesOfString(".json", withString: "")
let f2 = s2.stringByReplacingOccurrencesOfString(".json", withString: "")
let arr1 = f1.componentsSeparatedByString("-")
let arr2 = f2.componentsSeparatedByString("-")
var int1 = Int(arr1[0])
var int2 = Int(arr2[0])
if int1 < int2 {
return true
}
else if int1 > int2 {
return false
}
else {
int1 = Int(arr1[1])
int2 = Int(arr2[1])
if int1 < int2 {
return true
}
else if int1 > int2 {
return false
}
else {
return true
}
}
});
print(fileNames)
Try this...
var fileNames = ["87-1.json", "7-4.json", "102-4.json"]
// Modded OP's order to actually test sort
var sorted = fileNames.sort{ $0 < $1 }
print(sorted) // ["102-4.json", "7-4.json", "87-1.json"]
// Not sorted as OP "required", as they are string sorted, not number sorted
// Very simplistic solution
sorted = fileNames.sort { ($0 as NSString).integerValue < ($1 as NSString).integerValue}
print(sorted) // As OP requires, but...
// It won't sort on his count field - add a failing case...
fileNames = ["7-4.json", "87-1.json", "102-4.json", "102-1.json"]
sorted = fileNames.sort { ($0 as NSString).integerValue < ($1 as NSString).integerValue}
print(sorted) // ["7-4.json", "87-1.json", "102-4.json", "102-1.son"]
// WRONG!
// Define a simple function that parses his strings into tuples.
// This assumes that the Strings are valid, and fails safe if not.
// If you want more validation, add it yourself!
func myParse(s: String) -> (Int, Int) {
let c = s.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: "-."))
switch c.count {
case 0:
print("Careful Will Robinson!")
return (0, 0)
case 1:
print("Careful Will Robinson!")
return ((c[0] as NSString).integerValue, 0)
default:
return ((c[0] as NSString).integerValue, (c[1] as NSString).integerValue)
}
}
let test = fileNames.map { myParse($0) }
print("\(test)") // Test execution of function
sorted = fileNames.sort { (s1: String, s2: String) -> Bool in
let t1 = myParse(s1)
let t2 = myParse(s2)
if t1.0 == t2.0 {
return t1.1 < t2.1
} else {
return t1.0 < t2.0
}
}
print(sorted) // As required ["7-4.json", "87-1.json", "102-1.json", "102-4.json"]
I'm struggling with something that shouldn't be too difficult but I can't figure it out I have a number of Arrays with different values and I want to find the common values all of the Arrays have, see example below:
var arrayOne:Array = ["1","2","3"];
var arrayTwo:Array = ["1","2","7"];
var arrayThree:Array = ["1","2","9","12"];
_resultArray = ["1","2"];
Any help is appreciated.
You can do something like:
///Returns common values between to arrays
function getCommonValues(array1:Array, array2:Array):Array
{
var len1:int = array1.length;
var len2:int = array2.length;
var toReturn:Array = new Array();
for(var i:int = 0; i < len1; i++){
for(var n:int = 0; n < len2; n++){
if(array1[i] == array2[n]){
toReturn.push(array1[i]);
}
}
}
return toReturn;
}
Then do something like:
var arrayOneAndTwo:Array = getCommonValues(arrayOne,arrayTwo);
var _resultArray:Array = getCommonValues(arrayOneAndTwo,arrayThree);
Optionally you can modify the function to include all three arrays in the comparison, which would be more efficient.
Edit
If you want to process an unknown amount of arrays you can add:
///Returns common values between X number of sub arrays
function getCommonValuesFromSubArrays(papaArray:Array):Array
{
if(papaArray.length < 2){ return papaArray; }
var toReturn:Array = papaArray[0];
for(var a:int = 1; a < papaArray.length; a++){
toReturn = getCommonValues(toReturn, papaArray[a]);
}
return toReturn;
}
Then something like:
var arr1:Array = ["one","two","three","four","five"];
var arr2:Array = ["one","two","five","six"];
var arr3:Array = ["one","two","three","four","five"];
var arr4:Array = ["one","two","three","four","five"];
var bigOlArray:Array = [arr1,arr2,arr3,arr4];
var _results:Array = getCommonValuesFromSubArrays(bigOlArray);
I would use a function to concatenate all arrays, sort by numerical value, and collect all items that are available exactly as many times as the number of arrays that were passed in as parameters:
var arrayOne : Array = [ "1", "2", "3" ];
var arrayTwo : Array = [ "1", "2", "7" ];
var arrayThree : Array = [ "1", "2", "9", "12" ];
// you can pass in any number of Arrays
trace ( searchArraysForCommonItems ( arrayOne, arrayTwo, arrayThree ) ); // returns ["1", "2"]
function searchArraysForCommonItems ( ...args : * ) : Array
{
var searchArray : Array = [];
for each ( var arr:Array in args)
searchArray = searchArray.concat ( arr );
var resultArray : Array = [];
var last : String;
var times : int = 0;
for each ( var str : String in searchArray.sort ( Array.NUMERIC ))
if (last == str) times++;
else
{
if (times == args.length) resultArray.push ( last );
last = str;
times = 1;
}
return resultArray;
}
Of course, you can (and should) use Vector.<String> instead of Array wherever possible to improve performance, but always remember that Array.sort() is a native function and very fast...
I would use the Array.filter() Function to achieve this:
var _resultArray:Array = arrayOne.filter(
function(item:String, index:int, arr:Array):Boolean
{
return (arrayTwo.indexOf(item) != -1 && arrayThree.indexOf(item));
}
);
This will loop over arrayOne and return an array with the values that both appear also in arrayTwo and arrayThree.
Edit: And here is a function that will take any number of arrays and return the common values:
function getCommonValues(arrayOne:Array, ... arrays:Array):Array
{
var _resultArray:Array = arrayOne.filter(
function(item:String, index:int, arr:Array):Boolean
{
return arrays.every(
function (a:Array, index2:int, arr2:Array):Boolean
{
return a.indexOf(item) != -1;
}
);
}
);
return _resultArray;
}
Usage:
resultArray = getCommonValues(arrayOne, arrayTwo, arrayThree, arrayFour);
The function has another nested closure inside the first one, so might be a bit hard to understand, but I tested it, it works.