nsdictionary with arrays nspredicate filtering - ios

I have a tableview that i want to search through with a searchable. It worked before but when i added sections i got into trouble because i had to change from arrays to dictionary.
So basically i have a NSDictionary that looks like this
{ #"districtA": array with point objects, #"districtB": array with point objects}
I need to filter them based on the point objects.name that is in the arrays. After that i want to create a new nsdictionary with the filtered objects in it.
I tried at least 10 different methods but i can't figure it out so i think this is the only way that i am most positive that should work.
This is the only way i can think of if there is an easier way or more logic way please tell me.
-(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope {
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.name BEGINSWITH[c] %#",searchText];
//create new array to fill
NSArray *arrayWithFilteredPoints = [[NSArray alloc] init];
//loop through the values and put into an rray based on the predicate
arrayWithFilteredPoints = [NSArray arrayWithObject:[[self.PointList allValues] filteredArrayUsingPredicate:predicate]];
NSMutableDictionary *dict = [#{} mutableCopy];
for (Point *point in arrayWithFilteredPoints) {
if (![dict objectForKey:Point.district])
dict[Point.district] = [#[] mutableCopy];
[dict[Point.district]addObject:Point];
}
self.filteredPointList = dict;
self.filteredDistrictSectionNames = [[dict allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];}
This results in a crash, it happens of course where the predicate is used but i don't know how to debug what predicate i should use:
on 'NSInvalidArgumentException', reason: 'Can't do a substring operation with something that isn't a string (lhs = (
West ) rhs = w)'

I have read the comments and you are right. There was something wrong with my code.
I changed the logic, i added some more steps (like creating NSArray without needing it) to make the solution clear
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.name BEGINSWITH[c] %#",searchText];
//1. create new array to fill only the Points from the dictionary
NSArray *allPoints = [self.PointList allValues];
NSMutableArray *allPointObjects = [[NSMutableArray alloc]init];
for (NSArray *array in allPoints) {
for (Point *point in array) {
[allPointObjects addObject:point];
}
}
//2. loop through allPointObjects and put into an mutablearray based on the predicate
NSArray *arrayWithFilteredPoints = [[NSArray alloc] init];
arrayWithFilteredPoints = [allPointObjects filteredArrayUsingPredicate:predicate];
NSMutableDictionary *dict = [#{} mutableCopy];
for (Point *point in arrayWithFilteredPoints) {
if (![dict objectForKey:point.district])
dict[point.district] = [#[] mutableCopy];
[dict[point.district]addObject:Point];
}
self.filteredPointList = dict;
self.filteredDistrictSectionNames = [[dict allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
I wanted a filtered nsdictionary at the end that i can pass back to my tableview that reads the dictionary objects based on the keys (districts)

It seems clear from your description that [self.PointList allValues] is not an array of Point objects but an array of arrays of Point objects. That is the source of your difficulty, including your original crash.
You need to decide what to do about that; for example, if you want just one big array of Point objects, then flatten the array of arrays before you filter. I can't advise you further because it is not obvious to me what ultimate outcome you desire.
EDIT You've now modified your code and I can see more clearly what you're trying to do. You have a dictionary whose values are arrays of points, and you are trying to filter some of the points out of each array. What I would have done is to do that - i.e., run thru the keys, extract each array, filter it, and put it back (or delete the key if the array is now empty). But I can see that what you are doing should work, because you have cleverly put the keys into the points to start with, so you can reconstruct the dictionary structure from that.

Related

ios - Compare the value of objects in array and put in same section

im currently having issue with the logical of array and object, hope everyone can cure my dumbness, thanks!
Here's what im having:
NSArray data = #[#[#"year",#"name"],
#[#"2015",#"A"],
#[#"2014",#"B"],....
];
//have 100 small array, year can be similar
So i wanna ask how can i loop through them, compare the year of the object with the next object, then if the year is same, put it into a NSDictionary similar to the data array but with the key = the year:
NSDictionary dict = #[#"year":#[#"year",#"name"],
#"2015":#[#[#"2015",#"A"],#[#"2015",#"C"]],
#"2014":#[#"2014",#"B"],
#"2013":#[#"2013",#"D"],...
];
What i tried using predicate give me what i want...but i not sure how to do it with like many different kind of year (i think this is wrong, not sure)
NSString *searchTerm = #"2015";
//predicate1 is compare all the value with 2015, same then product array of them, predicate2 is product array of all array that dont have 2015 inside
NSPredicate *predicate1 = [NSPredicate predicateWithFormat:#"ANY SELF == %#", searchTerm];
NSArray *filtered1 = [data filteredArrayUsingPredicate:predicate1];
NSLog(#"%#", filtered1);
NSPredicate *predicate2 = [NSPredicate predicateWithFormat:#"ANY SELF != %#", searchTerm];
NSArray *filtered2 = [data filteredArrayUsingPredicate:predicate2];
NSLog(#"%#", filtered2);
This give me 2 array that have same year in small array inside
//output of 2 array:
filtered1 = #[#[#"2015",#"diff name"],
#[#"2015",#"A"],..
];
filtered2 = #[#[#"other year",#"diff name"],
#[#"2014",#"B"],...
];
What i think is that get the year of first small array, then compare with the year of the rest 99 small array, product the array of that first year, get the other small array, then do it again...but not sure how to implements it
Use a for loop and check against the previous record, I didnt 100% understand what you want to do when you have a successful find but this should work
NSString *prevData;
NSMutableArray *newData=[NSMutableArray array];
//check the last one
for (int i=0;i< data.count;i++)
{
NSArray currentData= [data objectAtIndex:i];
if(i!=0 && ([currentData objectAtIndex:0] isEqualTo:[prevData objectAtIndex:0]))
{
//add the data to newData
[newData addObject:currentData];
}
prevData=currentData
}

Compare objects in two Collections

I have the following scenario:
I have two collection classes (could be NSArray, NSMutableArray, NSSet, NSOrderedSet or whatever would be best suited for this case), which hold unique objects of the same type (unique in the sense that for all objects in the collections for no two elements the isEqual method would return true).
Lets say the first collection instance holds the following objects (1,2,3,4,5) and the second one (2,3,4,6,7). Now I need a method that returns the difference between the two collections, with the extra info what exactly the difference from each collection was.
An example result for the example would be: (1,5) was removed from the first collection and (6,7) added two the second collection.
I know if I use the NSMutableArray with a sorted list and decide which list has more elements than the other, I could use removeObjectsInArray to get a list of the different objects (like described in Compare two arrays with the same value but with a different order or in How to compare and remove common objects( NSDictionaries) from 2 NSMutableArray?), but don't really know which objects was in which collection. I could create a temporary collection and put the result of removeObjectsInArray in that array and compare the other two initial arrays with the temporary array. Seems little verbose though. Is there a better way that I don't know of?
I found a much slicker way for you to do what you want by using NSPredicate. When I run the following code:
NSArray *firstArray = [[NSArray alloc] initWithObjects:#"1",#"2",#"3",#"4",#"5",#"6",#"7", nil];
NSArray *secondArray = [[NSArray alloc] initWithObjects:#"1",#"2",#"3",#"8",nil];
NSArray *itemsMissingFromSecondArray = [firstArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"NOT SELF IN %#", secondArray]];
NSArray *itemsMissingFromFirstArray = [secondArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"NOT SELF IN %#", firstArray]];
NSLog(#"itemsMissingFromFirstArray=%#\nitemsMissingFromSecondArray=%#", itemsMissingFromFirstArray, itemsMissingFromSecondArray);
I get the following output showing what was missing from each array that was in the other array:
itemsMissingFromFirstArray=(
8
)
itemsMissingFromSecondArray=(
4,
5,
6,
7
)
Less code than sorting and merging, doesn't use a bunch of temporary arrays, and simple enough to read.
NOTE: If someone also wants to know the items that are in both arrays, the solution is similarly simple:
NSArray *itemsFoundInBothArrays = [firstArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"SELF IN %#", secondArray]];
I think if you want to know the difference, you can make use of NSMutableSet and the minusSet function.
[set1 minusSet:set2];
will give you the elements in set1 but not in set2 straight away. So you don't need any temp collection and compare with original collection again.
Otherwise, if you only want to remove the elements, you can make use of NSArray and do sth like:
[secondArray removeObjectsInArray:firstArray];
Edited:
To find all the diff in one shot:
[ [set1 unionSet:set2] minusSet: [set1 intersectSet:set2] ];
+ (NSArray *) removeObjectsFromArray :(NSArray *)arrayToRemoveFrom thatAreAlsoIn:(NSArray *)arrayOfItemsToRemove
{
NSMutableArray *newArray = [[NSMutableArray alloc] initWithArray:arrayToRemoveFrom];
[newArray removeObjectsInArray:arrayOfItemsToRemove];
return newArray;
}
+(void) findArrayDifferences
{
NSArray *bigArray = [[NSArray alloc] initWithObjects:#"1",#"2",#"3",#"4",#"5",#"6",#"7", nil];
NSArray *smallArray = [[NSArray alloc] initWithObjects:#"1",#"2",#"3",#"8",nil];
NSArray *itemsInBigArrayThatAreNotInSmallArray = [self removeObjectsFromArray:bigArray thatAreAlsoIn:smallArray];
NSArray *itemsThatAreInBothArrays = [self removeObjectsFromArray:bigArray thatAreAlsoIn:itemsInBigArrayThatAreNotInSmallArray];
NSArray *itemsInSmallArrayThatAreNotInBigArray = [self removeObjectsFromArray:smallArray thatAreAlsoIn:itemsThatAreInBothArrays];
NSLog(#"itemsInBigArrayThatAreNotInSmallArray=%#\nitemsThatAreInBothArrays=%#\nitemsInSmallArrayThatAreNotInBigArray=%#", itemsInBigArrayThatAreNotInSmallArray, itemsThatAreInBothArrays, itemsInSmallArrayThatAreNotInBigArray);
}
This results in the following output:
itemsInBigArrayThatAreNotInSmallArray=(
4,
5,
6,
7
)
itemsThatAreInBothArrays=(
1,
2,
3
)
itemsInSmallArrayThatAreNotInBigArray=(
8
)

Check if an object exist in a NSMutableArray of NSDictionary

i have an NSMutableArray that contains some NsDictionary with NSstring for differents Keys.
Somethings like:
NSDictionary *ExempleDictionary = [NSDictionary dictionaryWithObjectsAndKeys:[Date objectAtIndex:sender.tag],#"DATE",[Time objectAtIndex:sender.tag],#"TIME", nil];
I'd like to check if a particular object with DATE=xxx && TIME=xxx exist in the Array.
Any idea?!
You can do the search with NSPredicate:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.DATE=%# AND SELF.TIME=%#", dateVal, timeVal];
NSArray *filteredArray = [myArray filteredArrayUsingPredicate:predicate];
filteredArray contains an NSArray of all NSDictionary objects matching the specified date and time condition. You can retrieve the matching objects by iterating the filtered array.
You can use NSArray's containsObject: (if you have a reference to the dictionary laying around) or indexOfObjectIdenticalTo: (if you want to check if an element identical to the one you are passing -but not necessarily the same object- is in the array).
Both are explained in the docs:
containsObject
indexOfObjectIdenticalTo

Multiple dictionaries within an array and Checking for duplicate keys - Objective C

I have an array which contains multiple Dictionaries each one with 3 keys (#"date", #"username", #"text").
What I want to check for, is whether the same user (#"username") exists in more than one dictionary in that Array. And, if she does, combine the text for those "duplicates" into one dictionary.
I have considered this answer to check for duplicates and this one
but I cannot figure out how to combine these two.
Jumping in here because although I think you should work on the code yourself first, I think Miro's answer is more complicated than the issue requires and though I like the idea of using predicates in Greg's answer, here's a 3rd solution that (1) wouldn't require you to change your data structure and (2) references the necessary loops...
The way I'd do it: Create an NSMutableArray then start adding the usernames in order. If the NSMutableArray already contains the username though, don't add another instance of the username, but instead merge the dictionary info.
ex.
// Note: I'm calling your array of user dictionaries userArray.
// Create a username array to store the usernames and check for duplicates
NSMutableArray *usernames = [[NSMutableArray alloc] init];
// Create a new userArray to store the updated dictionary info, merged
// entries et. al.
NSMutableArray *newUserArray = [[NSMutableArray alloc] init];
// Go through the array of user dictionaries
for (NSDictionary *userDict in userArray) {
// If the usernames array doesn't already contain the username,
// add it to both the usernames array and the newUserArray as is
if (![usernames containsObject:[userDict objectForKey:#"username"]]) {
[usernames addObject:[userDict objectForKey:#"username"]];
[newUserArray addObject:userDict];
}
// Otherwise, merge the userArray entries
else {
// Get a mutable copy of the dictionary entry at the first instance
// with this username
int indexOfFirstInstance = [usernames indexOfObject:[userDict objectForKey:#"username"]];
NSMutableDictionary *entry = [[newUserArray objectAtIndex:indexOfFirstInstance] mutableCopy];
// Then combine the "text" or whatever other values you wanted to combine
// by replacing the "text" value with the combined text.
// (I've done so with a comma, but you could also store the value in an array)
[entry setValue:[[entry objectForKey:#"text"] stringByAppendingString:[NSString stringWithFormat:#", %#", [userDict objectForKey:#"text"]]] forKey:#"text"];
// Then replace this newly merged dictionary with the one at the
// first instance
[newUserArray replaceObjectAtIndex:indexOfFirstInstance withObject:entry];
}
}
Maybe something like this [untested] example? Loop through, maintain a hash of existing items, and if a duplicate is found then combine with existing and remove.
NSMutableArray main; // this should exist, with content
NSMutableDictionary *hash = [[NSMutableDictionary alloc] init];
// loop through, backwards, as we're attempting to modify array in place (risky)
for(int i = [main count] - 1; i >= 0; i--){
// check for existing
if(hash[main[i][#"username"]] != nil){
int existingIdx = [hash[main[i][#"username"]] integerValue]; // get existing location
main[existingIdx][#"text"] = [main[existingIdx][#"text"] stringByAppendingString:main[i][#"text"]]; // "combine text" .. or however you'd like to
[main removeObjectAtIndex:i]; // remove duplicate
} else {
[hash setValue:[[NSNumber alloc] initWithInt:i] forKey:main[i][#"username"]]; // mark existance, with location
}
}
If you use NSMutableDictionary, NSMutableArray and NSMutableString you can do it with predicate like that:
NSMutableDictionary *d1 = [#{#"username": #"Greg", #"text" : [#"text 1" mutableCopy]} mutableCopy];
NSMutableDictionary *d2 = [#{#"username": #"Greg", #"text" : [#"text 2" mutableCopy]} mutableCopy];
NSMutableDictionary *d3 = [#{#"username": #"John", #"text" : [#"text 3" mutableCopy]} mutableCopy];
NSMutableArray *array = [#[d1, d2, d3] mutableCopy];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"username = %#", #"Greg"];
NSArray *filterArray = [array filteredArrayUsingPredicate:predicate];
NSMutableDictionary * firstDict = filterArray[0];
for (NSDictionary *d in filterArray)
{
if (firstDict != d)
{
[firstDict[#"text"] appendString:d[#"text"]];
[array removeObject:d];
}
}

Get distinct entity objects from NSMutableArray using NSPredicate in iPhone sdk [duplicate]

This question already has answers here:
Removing duplicates from NSMutableArray
(9 answers)
Closed 10 years ago.
I have an NSMutableArray which has entity class object as its objects.
Now I want to remove the distinct objects from it. Consider following example
Entity *entity = [[Entity alloc] init];
entity.iUserId = 1;
entity.iUserName = #"Giri"
[arr addObject:entity];
Entity *entity = [[Entity alloc] init];
entity.iUserId = 2;
entity.iUserName = #"Sunil"
[arr addObject:entity];
Entity *entity = [[Entity alloc] init];
entity.iUserId = 3;
entity.iUserName = #"Giri"
[arr addObject:entity];
Now I want only two objects in the Array by removing the duplicate iUserName. I know the way by iteration but I want it without iterating it like predicate or some other way.
If anyone knows then please help me.
I had tried using [arr valueForKeyPath:#"distinctUnionOfObjects.iUsername"]; but it does not return me the entired object.
This question is totally different than the questions which are asked previously. Previously asked question is for getting the distinct objects is correct but they uses looping & I don't want this. I want it from NSPredicate or any other simple option which avoids looping.
EDIT: You can't do what you want to without looping over the array manually and building up a new array. The answer below won't work because it assumes that there are only at most two duplicates.
NSMutableArray *filteredArray = [NSMutableArray array];
for (Entity *entity in arr)
{
BOOL hasDuplicate = [[filteredArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"iUserName == %#", entity.iUserName]] count] > 0;
if (!hasDuplicate)
{
[filteredArray addObject:entity];
}
}
This will look for duplicates in the filtered array as it builds it.
Begin Original Answer
You can't use an NSSet because the Entity instances would have to return NSOrderedSame in compareTo:, which isn't a good idea since you shouldn't use names as unique identifiers.
You can use predicates, but they'll still loop over the array in an O(n^2) time without some optimization.
NSArray *filteredArray = [arr filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(Entity *evaluatedObject, NSDictionary *bindings) {
return [[arr filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"iUserName == %#", evaluatedObject.iUserName]] count] > 1;
}]];
That'll work fine. You could make it even faster by sorting the array by the iUserName property first and doing a linear scan over the sorted array (stopping when you see the first duplicate). That's a lot of work if you're dealing with small sample sizes (say, under ten thousand or so). It's probably not worth your time, so just use the code above.
Well you have a few options (that I can think of).
Use a NSSet instead of a NSArray.
Use a for loop (but you don't want to iterate through the array)
Use a predicate search iUserName to see if the name exists before adding it to the array.
Something like:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"iUserName == 'Giri'"];
NSArray *searchArray = [arr filterUsingPredicate:predicate];

Resources