I have a NSMutableDictionary in my objective c class with different pair keys values.
({Name=John; date=20070506; type=5; value= 125;},
{Name=Tracy; date=20040506; type=2; value = 237; },
{Name=Tracy; date=20040506; type=5; value = 124; },
...)
I can sum all values with the next code, but I can't get this in the same object in NSMutableDictionary.
NSNumber *amountSum = [CATransaction valueForKeyPath:#"#sum.value"];
How could I sum the values for all objects with the same type and show this like one unique object? For example:
({Name=John; date=20070506; type=5; value= 249;},
{Name=Tracy; date=20040506; type=2; value = 237; },
...)
Could I use a collection operator like this: Collections operators to do this??
thanks!
Get all the values for that valueForKey, so [Yourarray valueForKey:#"keyName"] will give you each value and finally you can loop over and sum all the values in array.
int total=0;
NSMutableDictionary *yourMutableDict=[[NSMutableDictionary alloc] init];
for (;;)
{
int value=[[Yourarray objectAtindex:i] valueForKey:#"keyName"];
total=total+value;
}
[yourMutableDict setValue:[NSNumber numberWithInteger:total] forKey:#"mySUM"];
NSLog(#"%#",[yourMutableDict objectForKey:#"mySUM"]);
Related
I have a question about NSMutableDictionary,
Let's say I have two set of NSMutableDictionary:
NSMutableDictionary *oddNumber
NSMutableDictionary *randomNumber
Is there a function to check value of randomNumber is SUBSET of value of oddNumber or not?
You can do something like this,
NSMutableDictionary *oddNumber;
NSMutableDictionary *randomNumber;
// Create arrays
NSArray *arroddNumber = [oddNumber allValues];
NSArray *arrrandomNumber = [oddNumber allValues];
// Turn the arrays into sets and intersect the two sets
NSMutableSet *oddNumberSet = [NSMutableSet setWithArray:arroddNumber];
NSMutableSet *randomNumbersSet = [NSMutableSet setWithArray:arrrandomNumber];
[oddNumberSet intersectSet:randomNumbersSet];
// The Values present in both arrays
NSLog(#"Common Values : %#", oddNumberSet);
You could get the values for each dictionary using the values method. This returns an array. You could then convert these arrays to sets, which have methods to check if one set is a subset of another.
Look at the values that you have. Make sure they have an isEqual: method and a hash method, so you can add them to a set. Create an NSSet with all values of the second dictionary, then iterate through the first dictionary and check which values are in the set.
Note that creating a set with N values takes O (N) time if the values have a decent hash function, and looking up a value in a set is constant time.
Short:
BOOL isSubset = [[oddNumber dictionaryWithValuesForKeys:[randomNumber allKeys]] isEqualToDictionary:randomNumber]
or faster:
__block BOOL isSubset = YES;
[randomNumber enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop){
id value = [oddNumber objectForKey:key];
if (!value || ![value isEqual:obj]) {
isSubset = NO;
*stop = YES;
}
}];
This is a core function question. I always dealt with this problem on the database side, by I can't do it for this case and I am stumped. I want to count the distinct values. Let's say I have an array
Array = {a,a,a,a,b,b,b,b,c,c,c,c}
And what I want is simply to get
Result = {[a,4],[b,4],[c,4]} or
ResultDistinct = { a, b, c} , ResultCount = {4,4,4}
I am fine with whatever format as long as it is fast and neat.
Use NSCountedSet.
NSArray *myArray = ... // array with all the a, b, and c values
NSCountedSet *set = [[NSCountedSet alloc] initWithArray:myArray];
for (id obj in set) {
NSLog(#"There are %d instances of %#", [set countForObject:obj], obj);
}
I have NSArray of NSDictionaries I need to extract 2 values or remove the values I don't need from the dictionary in the example below I need to remove id and NumberValue. any of you knows how can I do that?
Array: (
{
customerUS= {
DisplayName = "level";
InternalName = "Number 2";
NumberValue = 1;
id = xwrf
},
customerCAN= {
DisplayName = "PurchaseAmount";
InternalName = "Number 1";
NumberValue = 3500;
id = adf;
};
}
)
I'll really appreciate your help.
First thing, You can not remove/insert/update value in (immutable) NSDictionary/NSArray you need to convert NSDictionary/NSArray to (mutable) NSMutableDictionary/NSMutableArray.
such like
NSArray *myArr = ....;
NSMutableArray *newMutableArr = [myArr mutableCopy];
Then you can change in newMutableArr.
Such like
for(int i = 0 ; i < newMutableArr.count ; i ++)
{
[[newMutableArr objectAtIndex:i] removeObjectForKey:#"id"];
[[newMutableArr objectAtIndex:i] removeObjectForKey:#"NumberValue"];
}
EDITED:
Without Use of for loop and removeObjectForKey, if you have array of dictionary and both are mutable then you can also delete a key and its object from all elements of the array like this:
[newMutableArr makeObjectsPerformSelector:#selector(removeObjectForKey:) withObject:#"id"];
[newMutableArr makeObjectsPerformSelector:#selector(removeObjectForKey:) withObject:#"NumberValue"];
I would advice you to read Apple documents.
For modifying any Collection object after it is created, you need the mutable version.
For NSDictionary we have NSMutableDictionary. Read here.
We have a method for removing objects:
- (void)removeObjectForKey:(id)aKey
There are other methods as well. You can easily refer them in the above mentioned documentation.
Find out removeObjectForKey for deleting record from NSMutabledictionary.
removeObjectForKey pass the key value whatever you have like
all this are your key
DisplayName,
InternalName,
NumberValue,
id
do like this
removeObjectForKey:#"id";
First of all you have to convert the array to mutable array and then you can remove the key-value pairs from dictionary.
NSMutableArray *mutableArray = [yourArray mutableCopy];for(int i=0;i<mutableArray.count;i++){ NSMutableDictionary *outerDictionary = [mutableArray objectAtIndex:i]; for(NSString *key in outerDictionary.allKeys){ NSMutableDictionary *innerDictionary = [outerDictionary objectForKey:key]; [innerDictionary removeObjectForKey:#"id"]; [innerDictionary removeObjectForKey:#"NumberValue"]; }
}
I have a Person NSDictionary, whose key is the Name of the person, and the object is an NSDictionary with two keys: his nickname (NSString) and his age (NSNumber).
I would like to end up with the Person dictionary sorted by the ascending order of their age, so that I could get the name of the youngest and the oldest person.
What is the best way to do it?
Thanks!
There are a few convenience methods defined in NSDictionary to sort items by values and get back the sorted keys.
See docs,
keysSortedByValueUsingComparator:
keysSortedByValueUsingSelector:
keysSortedByValueWithOptions:usingComparator:
I'm guessing you're using the modern Objective-C syntax and the age is actually represented as numbers. Here's how it looks:
[people keysSortedByValueUsingComparator:(NSDictionary *firstPerson, NSDictionary *secondPerson) {
return [firstPerson[#"age"] compare:secondPerson[#"age"]];
}];
Some languages offer sorted dictionaries, but the standard NSDictionary is inherently unsorted. You can get all the keys, sort the key array and then walk over the dictionary according to the sorted keys. (NSDictionary has several convenience methods for this use case that I didn’t know about, see Anurag’s answer.)
Your case is a bit more complex, one way to solve it is to introduce a temporary dictionary mapping ages to names. But if you’re only after the minimum and maximum ages, just iterate over all persons and keep track of the maximum & minimum ages and names:
NSString *oldestName = nil;
float maxAge = -1;
for (NSString *name in [persons allKeys]) {
NSDictionary *info = persons[name];
float age = [info[#"age"] floatValue];
if (age > maxAge) {
oldestName = info[#"nick"];
maxAge = age;
}
}
And if we get back to the idea of sorting the dictionary, this could work:
NSArray *peopleByAge = [people keysSortedByValueUsingComparator:^(id a, id b) {
// Again, see Anurag’s answer for a more concise
// solution using the compare: method on NSNumbers.
float ageA = [a objectForKey:#"age"];
float ageB = [b objectForKey:#"age"];
return (ageA > ageB) ? NSOrderedDescending
: (ageB > ageA) ? NSOrderedAscending
: NSOrderedSame;
}];
As #Zoul said the standard NSDictionary is unsorted.
To sort it you can use an array, and I do things like that
//the dictionary is called dict : in my case it is loaded from a plist file
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:plistPath];
//make a dicoArray that is sorted so the results are sorted
NSArray *dicoArray = [[dict allKeys] sortedArrayUsingComparator:^(id firstObject, id secondObject) {
return [((NSString *)firstObject) compare:((NSString *)secondObject) options:NSNumericSearch];
}];
check the help for all the sort options. In the presented case the dictionary is sorted with keys treated as numeric value (which was the case for me).
If you need to sort another way the list of sort possibilities is
enum {
NSCaseInsensitiveSearch = 1,
NSLiteralSearch = 2,
NSBackwardsSearch = 4,
NSAnchoredSearch = 8,
NSNumericSearch = 64,
NSDiacriticInsensitiveSearch = 128,
NSWidthInsensitiveSearch = 256,
NSForcedOrderingSearch = 512,
NSRegularExpressionSearch = 1024
};
In iOS 9.2
// Dictionary of NSNumbers
NSDictionary * phoneNumbersDict = #{#"400-234-090":67,#"701-080-080":150};
// In Ascending Order
NSArray * keysArraySortedByValue = [phoneNumbersDict keysSortedByValueUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
return [obj1 compare:obj2];
}];
// In Descending Order
NSArray * keysArraySortedByValue = [phoneNumbersDict keysSortedByValueUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
return [obj2 compare:obj1];
}];
Here is the enum for NSComparisonResults.
enum {
NSOrderedAscending = -1,
NSOrderedSame,
NSOrderedDescending
};
typedef NSInteger NSComparisonResult;
Look at the NSDictionary's method that returns keys sorted by a selector. There are more than one such method. You get an array of sorted keys, then access the first and last and have your youngest and oldest person.
Suppose I have 4 integers.
int a = 4;
int b = 2;
int c = 4;
int d = 1;
How can I sort these integers from smallest to biggest. The output needs to be something like this: d, b, a, c Most methods of sorting only give me the value of the sorted integer. I need to know the name.
Edit: Well, I'm writing an AI algorithm. I have 4 ints that store direction priority. (If the AI comes into a wall, it chooses the next best direction). So, I need to find the lowest int, and if the AI can't move that way, I choose the second to lowest etc.
There appears to be some confusion here; in your example a is not the "name" for the value 4, it is the name of an integer variable which currently contains 4. In other words "a" is not part of the data of your program.
What I assume you mean is you have name/value pairs which you wish to sort using the value as key. A common way to do this is to define a type for your pair, create a collection, and sort the collection.
In plain C you can declare:
typedef struct
{
char *name;
int value;
} MyPair;
You can create an array of these and sort it using standard C functions for array sorting, using just the value field as the key.
In Objective-C you can declare a class for your pair:
#interface MyPair : NSObject
{
NSString *name;
int value;
}
// methods/properties
#end
You can create an NSMutableArray of instances of MyPair and then sort the array, again you just use the value property (or instance variable) when doing the comparisons for the sort algorithm.
There are other variations of course. Once sorted you can iterate through the sorted array and display the name field/property.
Here is an objective-c approach. Unfortunately, you will not have the fun of writing the AI portion, the sorting is built into the libraries already.
int north = 1, south = 3, east = 2, west =4;
NSDictionary * nDict = [NSDictionary dictionaryWithObjectsAndKeys:#"north", #"name", [NSNumber numberWithInt:north], #"value", nil];
NSDictionary * sDict = [NSDictionary dictionaryWithObjectsAndKeys:#"south", #"name", [NSNumber numberWithInt:south], #"value", nil];
NSDictionary * eDict = [NSDictionary dictionaryWithObjectsAndKeys:#"east", #"name", [NSNumber numberWithInt:east], #"value", nil];
NSDictionary * wDict = [NSDictionary dictionaryWithObjectsAndKeys:#"west", #"name", [NSNumber numberWithInt:west], #"value", nil];
NSArray * toBeSorted = [NSArray arrayWithObjects:nDict,sDict,eDict,wDict,nil];
NSArray * sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:#"value" ascending:NO]];
NSArray * sorted = [toBeSorted sortedArrayUsingDescriptors:sortDescriptors];
NSLog(#"sorted %#", sorted);
Output
2012-01-23 19:50:21.079 TestEnvironment[19792:207] sorted (
{
name = west;
value = 4;
},
{
name = south;
value = 3;
},
{
name = east;
value = 2;
},
{
name = north;
value = 1;
}
)
Now you can check the highest priority by
NSString * highestPriority = [[sorted objectAtIndex:0] objectForKey:#"name"];
Now you have some classes you can look up (NSArray, NSDictionary, NSSortDescriptor, NSNumber)
You've tagged this Objective-C, but you haven't written anything that suggests using Objective-C. If you want to use Objective-C, I'd put the elements into an NSMutableArray (they'll need to be converted to NSNumbers to do that), and have the array sort them, as seen here.
If you just want to put them into a straight C array, you could sort them using heapsort (), qsort(), or mergesort().