I have an object containing an array of NSNumbers (indexes) and an array of NSDictionaries (indexesTitles) corresponding to indexes, containing some info.
I have to call a method for each object.index and associate object.indexTitles to the returning results, saving them into a single array.
At the end of it, I want to remove indexes duplicates, preserving the associated indextTitles in an efficient way, because I'm working with large arrays.
NSMutableArray *resultArray = [NSMutableArray array];
NSMutableArray *titlesArray = [NSMutableArray array];
for(NSNumber *index in object.indexes)
{
NSArray *resultsIndexArray = [self methodThatReturnsAnArray];
NSString *indexTitleDictionary = [object.indexesTitles objectAtIndex:i];
for(NSNumber *resultId in resultsIndexArray)
{
[titlesArray addObject:indexDictionary];
[resultArray addObject:resultId];
}
i++;
}
[fullResultsArray addObject:titlesArray];
[fullResultsArray addObject:resultArray];
I've found that the most efficient way to remove duplicates is using an
NSOrderedSet like this:
NSOrderedSet *orderedSet = [NSOrderedSet orderedSetWithArray:resultArray];
resultArray = [orderedSet.array mutableCopy];
How can I remove the corresponding entries in titlesArray? how can I preserve the association?
I've also tried to use a NSDictionary like {resultId, titleDictionary} and storing them into an array, but I haven't found a efficient way to remove dictionaries with the same result, they are all too slow.
Any suggestion?
It is not completely clear to me what your problem is, maybe this will help:
A good way to remove duplicates is not to add them in the first place, replace:
for(NSNumber *resultId in resultsIndexArray)
{
[titlesArray addObject:indexDictionary];
[resultArray addObject:resultId];
}
with:
for(NSNumber *resultId in resultsIndexArray)
{
// only add if resultId not already in resultArray
if( ![resultArray containsObject:resultId] )
{
[titlesArray addObject:indexDictionary];
[resultArray addObject:resultId];
}
}
The containsObject: call requires a linear search, if your data set is large you might wish to change resultArray to an NSMutableSet and titlesArray to an NSMutableDictionary mapping from resultId to indexDictionary values.
HTH
Related
I have a UITableView and am displaying contents from my NSMutableArray. Following is array format
(
{
Name = "ANS";
VersionNo = 6;
},
{
Name = "O-Hydro";
Version = 6;
},
{
Name = "ANS";
Version = 6;
},
{
Name = "ANTIChorosAnticholinergic";
Version = 6;
}
)
From this I need to display only unique "Name" (like in this I can see 2 "ANS" I need only one).
How can I do this in iOS?
I tried following but its not working
uniqueArray= [[NSMutableSet setWithArray: groupDetails] allObjects];
but in this way I can do only for NSArray not NSMutableArray.
Pls help me
You can use following line of code to convert your NSArray to NSMutableArray,
NSArray *uniqueArray= [[NSMutableSet setWithArray:groupDetails] allObjects];
NSMutableArray *myMutableArray = [[NSMutableArray alloc] initWithArray:uniqueArray];
You could simply add mutableCopy.
But wait, before you do it. Arrays and sets have two differences:
Arrays can contain duplicates, sets cannot.
Arrays are ordered, sets are not.
So doing what you are doing, you lose the duplicates (intentionally), but the order, too (probably not intentionally).
I do not know, whether this is important for you, but for other readers it might be. So it is the better approach to do that with NSOrderedSet instead of NSSet:
NSOrderedSet *uniqueList = [NSOrderedSet orderedSetWithArray:array];
In many cases an ordered set is exactly what you want. (Probably it has been from the very beginning and the usage of NSArray was wrong. But sometimes you get an array.) If you really want an array at the end of the day, you can reconvert it:
array = [uniqueList.array mutableCopy];
If you just want an array of unique name values, you can use #distinctUnionOfObjects with valueForKeyPath -
NSArray *uniqueArray=[groupDetails valueForKeyPath:#"#distinctUnionOfObjects.name"];
But if you want the array to contain the dictionaries that correspond to the unique names then you need to do a little more work -
NSMutableArray *uniqueArray=[NSMutableArray new];
NSMutableSet *nameSet=[NSMutableSet new];
for (NSDictionary *dict in groupDetails) {
NSString *name=dict[#"name"];
if (![nameSet containsObject:name]) {
[uniqueArray addObject:dict];
[nameSet addObject:name];
}
}
I need help with the following:
I have an NSArray with NSStrings, I want to loop thru these strings and find a matching string, when match is found the strings after this match will be extracted into an NSDictionary until a certain other match is hit.
Here is an example:
NSArray *array = #[#"Fruit",#"Apple",#"Vegtable",#"Tomato",#"Fruit",#"Banana",#"Vegtable",#"Cucumber"];
So I want to loop thru this array and split it in 2 arrays one for fruit and one for vegetable.
Anyone can help with the logic?
Thanks
This is probably the simplest way to solve the problem:
NSArray *array = #[#"Chair",#"Fruit",#"Apple",#"Orange",#"Vegetable",#"Tomato",#"Fruit",#"Banana",#"Vegetable",#"Cucumber"];
NSMutableArray *fruitArray = [NSMutableArray array];
NSMutableArray *vegetableArray = [NSMutableArray array];
NSMutableArray *currentTarget = nil;
for (NSString *item in array)
{
if ([item isEqualToString: #"Fruit"])
{
currentTarget = fruitArray;
}
else if ([item isEqualToString: #"Vegetable"])
{
currentTarget = vegetableArray;
}
else
{
[currentTarget addObject: item];
}
}
In one iteration over the array, you just keep adding items to a result array using a pointer to one of two result arrays according to the last occurrence of the #"Fruit" or #"Vegetable" string.
This algorithm ignores all items before the first occurrence of the #"Fruit" or #"Vegetable" string, because the currentTarget is initialized to nil, which ignores the addObject: messages. If you want different behaviour, just change the initialization.
You said you wanted the results in a NSDictionary, but didn't specify what should be the key. If you want one NSDictionary with two keys, Fruit and Vegetable, and values NSArrays containing the items, just use the arrays previously created:
NSDictionary *dict = #{ #"Fruit": fruitArray, #"Vegetable": vegetableArray };
PS: You have a typo in your example, Vegtable instead of Vegetable. I corrected it in my code, so keep it in mind.
If I completely understand you:
NSArray *array = #[#"Fruit",#"Apple",#"Vegtable",#"Tomato",#"Fruit",#"Banana",#"Vegtable",#"Cucumber"];
NSMutableArray *fruits = [NSMutableArray array];
NSMutableArray *vegtables = [NSMutableArray array];
for (NSInteger i = 0; i < array.count; ++i){
if ([array[i] isEqualToString:#"Fruit"]){
++i;
[fruits addObject:array[i]];
}
else if ([array[i] isEqualToString:#"Vegtable"]){
++i;
[vegtables addObject:array[i]];
}
}
I'm working with a plist file at the moment but intend to switch over to json when the backend is finally built. So for the moment my plist is an array that contains a bunch of dictionaries.
I'd like to use this information to create a new array containing only the dictionaries with certain values.
For example. My plist contains a bunch of locations like so:
key: location value:example place name here
key: type value:indoor
I want to build an array containing only those with "indoor" set as the type value.
And then perhaps a second one containing all "outdoor" locations.
What's the best way to go about doing this, or perhaps I can be directed to a tutorial of some sort.
Thanks.
Simply loop through your array and add the qualifying dictionaries to a new array.
NSMutableArray *arrayIndoor = [NSMutableArray array];
NSMutableArray *arrayOutdoor = [NSMutableArray array];
NSString *type;
for (NSDictionary *dict in arrayPList) {
type = [dict objectForKey:#"type"];
if ([type isEqualToString:#"indoor"])
[arrayIndoor addObject:dict];
else if ([type isEqualToString:#"indoor"])
[arrayOutdoor addObject:dict];
}
All you are really needing to do is sort the array into two arrays. There isn't a direct method that I have seen that will do this for you. My suggestion would be to use a fast enumeration over the array and conditionally break it into two new arrays.
NSMutableArray *locations = [[NSMutableArray alloc] init];
NSMutableArray *type = [[NSMutableArray alloc] init];
for (NSDictionary *dict in MyPlistArray) {
if ([dict valueForKey:#"locationKey"]) {
[locations addObject:dict];
} else if ([dict valueForKey:#"typeKey"]) {
[type addObject:dict];
}
}
You might need to use a different method for determining which key to put in each array, but you get the general idea.
Also I'm assuming that you would want the arrays of dictionaries to persist after, so you can just set those up as properties instead of local variables.
I have an NSMutableArray of many NSDictionaries that contain keys like "Title". In some cases there are duplicates of dictionaries with the same "Title" but differences in the other keys.
How can I remove the dictionaries that have the same "Title" key and leave only one in the array?
Thanks
Sort the array using NSSortDescriptor on the key path 'title'. Next, loop over the array and build a new array:
NSString *lastTitle = nil;
NSMutableArray *result = [NSMutableArray array];
for (NSDictionary *d in array) {
NSString *testTitle = [d objectForKey:#"title"];
if (![testTitle isEqualToString:lastTitle]) {
[result addObject:d];
lastTitle = testTitle;
}
}
Now result contains your filtered list.
It's important to sort the array first for this algorithm to work.
I have an array of recommendedcar IDs, and another array of allcar IDs. From this, I have to take the recommendedcar images. First, I check whether the recommended carid is in my allcar id; if it is, I select the corresponding car images, and store them into NSArray.
This is the code I am using.
for (int i=0;i<[listOfCarId count];i++) {
for (int j=0;j<[_allCarID count];j++) {
tempAllCarId=[_allCarID objectAtIndex:j];
tempRecommendedCarId=[listOfCarId objectAtIndex:i];
if ([tempRecommendedCarId isEqualToString:tempAllCarId]) {
_recommendedCarImage=[_allCarImages objectAtIndex:j];
NSLog(#"finalImage%#",_recommendedCarImage);
}
}
}
_recommendedcarImage is NSMUtableArray; I want a NSArray. How can I convert it to a NSArray?
How can i replace the "_recommendedCarImage " with an NSArray?? Currently _recommendedCarImage is a mutable array.
Polymorphism. Since NSMutableArray is a subclass of NSArray, you can use it anywhere an NSArray is expected. You don't have to do anything.
Now its working,What i did is , I just copy the contents of Mutable array to NSarray
recommendedArray=[_recommendedCarImage copy];
An NSMutableArray is an NSArray already (as it's a subclass of NSArray), still you can do:
NSArray *array = [NSArray arrayWithArray:mutableArray];